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    <font size="7">Filesystem Library<br>
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<h1>Reference Documentation</h1>



<p><i>Headings and synopsis for recently added functionality are shown with a 
<span style="background-color: #CCFFCC">green background</span>. </i></p>



<h2><a name="TOC">Table of Contents</a></h2>

<table border="0" cellpadding="0" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="100%">
  <tr>
    <td width="33%" valign="top">
    <p><a href="#Introduction">Introduction</a><br>
    <a href="#Definitions">Definitions</a><br>
    <a href="#Conformance">Conformance</a><br>
    <a href="#Header-filesystem-synopsis">
    Header <code>&lt;boost/filesystem.hpp&gt;</code> synopsis</a><br>
    <a href="#Error-reporting">Error reporting</a><br>
    <a href="#class-path">Class <code>path</code></a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-Conversions"><code>path</code> conversions</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-Conversions-to-native-format"><code>path</code> 
    conversions to native format</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-Conversions-to-generic-format"><code>path</code> 
    conversions to generic format</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-Encoding-conversions"><code>path</code> 
    encoding conversions</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-Requirements"><code>path</code> requirements</a><br>
    &nbsp;&nbsp;&nbsp; <a href="#path-constructors"><code>path</code> constructors</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-assignments"><code>path</code> assignments</a><br>
    &nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-appends"><code>path</code> appends</a><br>
    &nbsp;&nbsp; &nbsp;<a href="#path-concatenation"><code>path</code> concatenation</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-modifiers"><code>path</code> modifiers</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-native-format-observers"><code>path</code> native 
    format observers</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-generic-format-observers"><code>path</code> generic 
    format observers</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-compare"><code>path</code> compare</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-decomposition"><code>path</code> decomposition</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-query"><code>path</code> query</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-iterators"><code>path</code> iterators</a><br>

&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-deprecated-functions"><code>path</code> deprecated functions</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-non-member-functions"><code>path</code> non-member functions</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-inserter-extractor"><code>path</code> inserters and extractors</a><br>
 &nbsp;<a href="#Class-filesystem_error">Class <code>filesystem_error</code></a><br>
&nbsp;&nbsp;&nbsp; <a href="#filesystem_error-members"><code>filesystem_error</code> 
    constructors</a><br>
&nbsp;&nbsp;&nbsp; <a href="#filesystem_error-path1"><code>filesystem_error</code> path1</a><br>
&nbsp;&nbsp;&nbsp; <a href="#filesystem_error-path2"><code>filesystem_error</code> path2</a><br>
&nbsp;&nbsp;&nbsp; <a href="#filesystem_error-what"><code>filesystem_error</code> what</a></td>
    <td width="33%" valign="top">
    <p>
    <a href="#Enum-file_type">Enum <code>file_type</code></a><br>
    <a href="#Enum-perms">Enum <code>perms</code></a><br>
    <a href="#file_status">Class 
    <code>file_status</code></a><br>
&nbsp;&nbsp;&nbsp;
    <a href="#file_status"> 
    <code>file_status</code></a><a href="#file_status-constructors"> constructors</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<code><a href="#file_status-modifiers">file_status-modifiers</a></code><a href="#directory_entry-observers"> observers</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<code><a href="#file_status-observers">file_status-observers</a></code><a href="#directory_entry-modifiers"> modifiers</a><br>
<a href="#Class-directory_entry">Class <code>directory_entry</code></a><br>
&nbsp;&nbsp;&nbsp;
<a href="#directory_entry-constructors"><code>directory_entry</code> constructors</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#directory_entry-observers"><code>directory_entry</code> observers</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#directory_entry-modifiers"><code>directory_entry</code> modifiers</a><br>
<a href="#Class-directory_iterator">Class  <code>directory_iterator</code></a><br>
&nbsp;&nbsp;&nbsp; <a href="#directory_iterator-members"><code>directory_iterator</code> 
    members</a><br>
<a href="#Class-recursive_directory_iterator">Class <code>recursive_directory_iterator</code></a><br>
    <a href="#Operational-functions">
    Operational functions</a><br>
    <code>&nbsp;&nbsp;&nbsp;&nbsp; <a href="#absolute">absolute</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#canonical">canonical</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#copy">copy</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#copy_directory">copy_directory</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#copy_file">copy_file</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#copy_symlink">copy_symlink</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#create_directories">create_directories</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#create_directory">create_directory</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#create_hard_link">create_hard_link</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#create_symlink">create_symlink</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#current_path">current_path</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#exists">exists</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#equivalent">equivalent</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#file_size">file_size</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#hard_link_count">hard_link_count</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#initial_path">initial_path</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;  i<a href="#is_directory">s_directory</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#is_empty">is_empty</a></code></td>
    <td width="34%" valign="top">
    <p>
    <code>&nbsp;&nbsp;&nbsp;&nbsp; <a href="#is_other">is_other</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#is_regular_file">is_regular_file</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#is_symlink">is_symlink</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#last_write_time">last_write_time</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#permissions">permissions</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#read_symlink">read_symlink</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#op-relative">
    <span style="background-color: #CCFFCC">relative</span></a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#remove">remove</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#remove_all">remove_all</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#rename">rename</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#resize_file">resize_file</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#space">space</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#status">status</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#status_known">status_known</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#symlink_status">symlink_status</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#system_complete">system_complete</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#temp_directory_path">temp_directory_path</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#unique_path">unique_path</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#weakly_canonical">
    <span style="background-color: #CCFFCC">weakly_canonical</span></a><br></code>
    <a href="#File-streams">File streams</a><br>
<a href="#path-decomposition-table">Path decomposition table</a><br>
    <a href="#long-path-warning">Warning: Long paths on Windows and the 
    extended-length <b>\\?\ </b>prefix</a><br>
<a href="#Acknowledgements">Acknowledgements</a><br>
<a href="#References">References</a><br>
&nbsp;</td>
  </tr>
</table>


<h2><a name="Introduction">Introduction</a></h2>

<p>This reference documentation describes components that C++ programs may use 
to perform operations involving file systems, including paths, regular files, 
and directories.</p>

<blockquote>
<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse"
  bordercolor="#111111" bgcolor="#D7EEFF" width="90%">
  <tr>
    <td width="100%" align="center" colspan="2">
    <p align="center"><b>C++11 Support</b><p align="left">This reference 
    documentation is written as if all compilers supported C++11. Where 
    possible, the implementation falls back to C++03 if a C++11 feature is not 
    available.</td>
  </tr>
  <tr>
    <td width="35%" align="center">
    <p>
    <b>C++11 Feature</b></td>
    <td width="65%" align="center">
    <p>
    <b>Action if not supported by compiler</b></td>
  </tr>
  <tr>
    <td width="35%" align="left">
    <p>
    <code>noexcept</code></td>
    <td width="65%" align="left">
    <p>Keyword omitted.</td>
  </tr>
  <tr>
    <td width="35%" align="left">
    <p>
    <code>constexpr</code></td>
    <td width="65%" align="left">
    <p>Keyword omitted.</td>
  </tr>
  <tr>
    <td width="35%" align="left">
    <p>R-value references</td>
    <td width="65%" align="left">
    <p>Function signature omitted.</td>
  </tr>
  <tr>
    <td width="35%" align="left">
    <p>New character types</td>
    <td width="65%" align="left">
    <p>The <code>boost::filesystem</code> interface doesn't use the 
    new types directly. It does use <code>u16string</code> and <code>u32string</code> 
    in namespace <code>boost</code>. These are typedefs to <code>std::u16string</code> 
    and <code>std::u32string</code> for C++11, or to <code>
    std::basic_string&lt;boost::u16_t&gt;</code> and <code>
    std::basic_string&lt;boost::u32_t&gt;</code> for C++03.</td>
  </tr>
  <tr>
    <td width="35%" align="left">
    <p>Defaulted and deleted functions</td>
    <td width="65%" align="left">
    <p>Workaround replacement functions provided.</td>
  </tr>
  <tr>
    <td width="35%" align="left">
    <p>Initializer lists</td>
    <td width="65%" align="left">
    <p>Not currently used.</td>
  </tr>
  <tr>
    <td width="35%" align="left">
    <p>Variadic templates</td>
    <td width="65%" align="left">
    <p>Not currently used.</td>
  </tr>
  <tr>
    <td width="35%" align="left">
    <p>Range-based for statements</td>
    <td width="65%" align="left">
    <p>Supporting functions always provided; they do no harm even for C++03 
    compilers.</td>
  </tr>
</table>
</blockquote>



<h2><a name="Conformance">Conformance</a> [fs.conformance]</h2>

<h3>ISO/IEC 9945 conformance [fs.conform.9945]</h3>
<p>Some behavior in this reference documentation is specified by reference to ISO/IEC 9945. How such behavior is actually implemented is unspecified.</p>
<blockquote>
<p>[<i>Note:</i> This constitutes an &quot;as if&quot; rule for implementation of 
operating system dependent behavior. In practice implementations will usually call native 
operating system API's. <i>—end note</i>]</p>
</blockquote>
<p>Implementations are encouraged to provide such behavior 
 
as it is defined by ISO/IEC 9945. Implementations shall document any 
behavior that differs from the behavior defined by ISO/IEC 9945. Implementations that do not support exact 
ISO/IEC 9945 behavior are 
encouraged to provide behavior as close to ISO/IEC 9945 behavior as is reasonable given the 
limitations of actual operating systems and file systems. If an implementation cannot provide any 
reasonable behavior, the implementation shall report an error in an 
implementation-defined manner.</p>
<blockquote>
<p>[<i>Note:</i> Such errors might be reported by an #error directive, a <code>
static_assert</code>, a <code>filesystem_error</code> exception, a special 
return value, or some other manner. <i>—end note</i>]</p>
</blockquote>
<p>Implementations are not required to provide behavior that is not supported by 
a particular file system.</p>
<blockquote>
<p>[<i>Example:</i> The <a href="http://en.wikipedia.org/wiki/FAT_filesystem">
FAT file system</a> used by some memory cards, camera memory, and floppy discs 
does not support hard links, symlinks, and many other features of more capable 
file systems. Implementations are only required to support the FAT features 
supported by the host operating system. <i>—end example</i>]</p>
</blockquote>
<p>The behavior of functions described in this 
reference 
may differ from their specification in 
the presence of <a href="#file-system-race">file system races</a>. No diagnostic is required.</p>
<p>If the possibility of a file system race would make it unreliable for a program to 
test for a precondition before calling a function described in this reference documentation, <i>
Requires</i> is not specified for the condition. Instead, the condition is 
specified as a <i>Throws</i> condition.</p>
<blockquote>
<p>[<i>Note:</i> As a design practice, preconditions are not specified when it 
is unreasonable for a program to detect them prior to calling the function. <i>
—end note</i>]</p>
</blockquote>
<h3>Operating system dependent conformance [fs.conform.os]</h3>
<p>Some behavior is specified in this reference documentation as being 
operating system dependent ([fs.def.osdep]). The operation system an 
implementation is dependent upon is implementation defined.</p>
<p>It is permissible for an implementation to be dependent upon an operating 
system emulator rather than the actual operating system.</p>
<blockquote>
<p>[<i>Example:</i> An implementation uses Cygwin, a Linux&reg; API emulator for 
some Windows&reg; operating system versions. The implementation would define Cygwin 
as its operating system. Users could refer to the Cygwin documentation to find 
details of the operating system dependent behavior.&nbsp; <i>—end example</i>]</p>
<p><span style="background-color: #E0E0E0"><i>It is user and conformance test 
detectable that such an implementation is running on Cygwin. Users would be 
misled and conformance tests would fail if the implementation defined Linux or 
Windows rather than Cygwin as the operating system, since real behavior is a 
blend of the two.</i></span> </p>
</blockquote>
<h2><a name="Definitions">Definitions</a> [fs.definitions]</h2>
<p>The following definitions  shall apply throughout this reference documentation:</p>
<h3><a name="operating system dependent">operating system dependent</a> behavior 
[fs.def.osdep]</h3>
<p>Behavior  that is dependent upon the behavior 
and characteristics of an operating system. See [fs.conform.os].</p>
<h3><a name="file">file</a> [fs.def.file]</h3>
<p>An object that can be written to, or read from, or both. A file 
has certain attributes, including type. File types include regular files 
and directories. Other types of files, such as symbolic links, may be supported by the 
implementation.</p>
<h3><a name="file-system">file system</a> [fs.def.filesystem]</h3>
<p>A collection of files and certain of their attributes.</p>
<h3><a name="filename">filename</a> [fs.def.filename]</h3>
  <p>The name of a file. Filenames <code>
  &quot;.&quot;</code>&nbsp; 
and <code>&quot;..&quot;</code>&nbsp; have special meaning. The follow characteristics of 
  filenames are operating system dependent:</p>
<ul>
  <li>
  <p>The permitted characters. See [<a href="#Operating-system-examples">fs.os.example</a>s].</p>
  </li>
  <li>
  <p>Specific filenames that are not permitted.</p>
  </li>
  <li>
  <p>Additional filenames that have special meaning.</p>
  </li>
  <li>
  <p>Case awareness and sensitivity during path resolution.</p>
  </li>
  <li>
  <p>Special rules that may apply to file types other than regular 
  files, such as directories.</p>
  </li>
</ul>
<h3><a name="path">path</a> [fs.def.path]</h3>
<p>A sequence of elements that identify 
the location of a file within a filesystem. The elements are the <i>root-name<sub>opt</sub></i>, <i>
root-directory<sub>opt</sub></i>, and an optional sequence of filenames. [<i>Note:</i> 
A <a href="#pathname">pathname</a> is the concrete representation of a path. <i>—end note</i>]</p>

<h3><a name="Absolute-path">absolute path</a> [fs.def.absolute-path]</h3>
<p>A path that 
unambiguously 
identifies the location of a file without reference to an additional starting 
location. The elements of a path that determine if it is absolute are 
operating system dependent.</p>

<h3><a name="Relative-path">relative path</a> [fs.def.relative-path]</h3>
<p>A path that 
is not absolute, and so only 
unambiguously 
identifies the location of a file when resolved relative to 
an implied starting location. The elements of a path that determine if it is 
relative are operating system dependent.&nbsp; [<i>Note:</i> 
Paths <code>&quot;.&quot;</code> and <code>&quot;..&quot;</code> are relative paths. <i>—end note</i>]</p>
<h3><a name="canonical-path">canonical path</a> [fs.def.cannonical-path]</h3>
<p>An absolute path that has 
no elements that are symbolic links, and no <code>&quot;.&quot;</code> or <code>&quot;..&quot;</code> elements.</p>
<h3><a name="pathname">pathname</a> [fs.def.pathname]</h3>
<p>A character string that represents 
the name of a 
path. Pathnames are formatted according to the generic pathname grammar or an 
operating system dependent 
native pathname format.</p>

<h3><a name="native-pathname-format">native pathname format</a> [fs.def.native]</h3>
<p>The operating system dependent pathname format accepted by the host operating system.</p>
<h3><a name="normal-form"><span style="background-color: #CCFFCC">normal form</span></a><span style="background-color: #CCFFCC"> path</span> [fs.def.normal]</h3>
<p>A path with no redundant current directory (<i>dot</i>) or parent directory (<i>dot-dot</i>) 
elements. The normal form for an empty path is an empty path. The normal form 
for a path ending in a <i>directory-separator</i> that is not the root directory 
is the same path with a current directory (<i>dot</i>) element appended.</p>
<h3><a name="link">link</a> [fs.def.link]</h3>
<p>A directory entry object that associates a 
filename with a file. On some file systems, several directory entries can 
associate names with the same file.</p>
<h3><a name="hard-link">hard link</a> [fs.def.hardlink]</h3>
<p>A link to an existing file. Some 
file systems support multiple hard links to a file. If the last hard link to a 
file is removed, the file itself is removed.</p>
<blockquote>
<p>[<i>Note:</i> A hard link can be thought of as a shared-ownership smart 
pointer to a file.<i> —end note</i>]<i> </i></p>
</blockquote>
<h3><a name="symbolic-link">symbolic link</a> [fs.def.symlink]</h3>
<p>A type of file with the 
property that when the file is encountered during pathname resolution, a string 
stored by the file is used to modify the pathname resolution.</p>
<blockquote>
<p>[<i>Note:</i> A symbolic link can be thought of as a raw pointer to a file. 
If the file pointed to does not exist, the symbolic link is said to be a 
&quot;dangling&quot; symbolic link.<i> —end note</i>]<i> </i></p>
</blockquote>
<h3><a name="file-system-race">file system race</a> [fs.def.race]</h3>
<p>The condition that occurs 
when multiple threads, processes, or computers interleave access and 
modification of 
the same object within a file system.</p>
<h2><a name="generic-pathname-format">Generic pathname format</a> [path.generic]</h2>
<p><i>pathname:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; root-name<sub>opt</sub> 
root-directory<sub>opt</sub> relative-path<sub>opt</sub></i></p>
<p><i>root-name:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </i>An 
operating system dependent name that identifies the starting location for 
absolute paths. </p>
<blockquote>
  <blockquote>
<p>[<i>Note:</i> Many operating systems define a name 
beginning with two <i>directory-separator</i> characters as a <i>root-name</i> 
that identifies network or other resource locations. Some operating systems define a single letter followed by a colon as a drive 
specifier - a <i>root-name</i> identifying a specific device such as a disc drive. <i>—end note</i>]</p>
  </blockquote>
</blockquote>
<p><i>root-directory:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
directory-separator</i></p>
<p><i>relative-path:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
filename<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; relative-path 
directory-separator<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; relative-path 
directory-separator filename</i></p>
<p><i>filename:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; name<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </i><code>&quot;.&quot;</code><i><br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </i><code>
&quot;..&quot;</code></p>
<p><i>preferred-separator:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </i>An 
operating system dependent directory separator character. May be a synonym for <i> <code>&quot;/&quot;</code>.</i></p>
<p><i>directory-separator:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <code>&quot;/&quot;<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &quot;/&quot;</code> directory-separator<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
preferred-separator<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
preferred-separator directory-separator</i></p>
<p>Multiple successive <i>directory-separator</i> characters are considered to 
be the same as one <i>directory-separator</i> character.</p>
<p>The <i>filename</i>
<code>&quot;.&quot;</code> is considered to be a reference to the current directory. The
<i>filename</i> <code>&quot;..&quot;</code> is considered to be a reference to the 
parent 
directory. Specific <i>filenames</i> may have special meanings for a particular 
operating system.</p>
<h2><a name="Operating-system-examples">Operating system dependent examples</a> (Informative) [fs.os.examples]</h2>
<p>Certain features are specified in this reference documentation as being operating system dependent. The following table shows the application of those 
specifications for operating systems that use the ISO/IEC 9945  or Windows&reg; application program interfaces 
(APIs).<sup>[footnote1]</sup></p>
<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111">
  <tr>
    <td valign="top" align="center">
    <p><b>Feature</b></td>
    <td valign="top" align="center">
    <p><b>Section</b></td>
    <td valign="top" align="center">
    <p><b>ISO/IEC 9945<br>
&nbsp;POSIX</b>&reg;<b> API</b></td>
    <td valign="top" align="center">
    <p><b>Windows</b>&reg;<b> API</b></td>
    <td valign="top" align="center">
    <p><b>Notes</b></td>
  </tr>
  <tr>
    <td valign="top">
    <p><code>path<br>
&nbsp;::value_type</code></td>
    <td valign="top">
    <p>[<a href="#class-path">class.path</a>]</td>
    <td valign="top">
    <p><code>char</code></td>
    <td valign="top">
    <p><code>wchar_t</code></td>
    <td valign="top">
    <p>&nbsp;</td>
  </tr>
  <tr>
    <td valign="top">
    <p><code>path::preferred<br>
&nbsp;_separator</code></td>
    <td valign="top">
    <p>[<a href="#class-path">class.path</a>]</td>
    <td valign="top">
    <p><code>'/'</code></td>
    <td valign="top">
    <p><code>L'\\'</code> (single backslash)</td>
    <td valign="top">
    <p>&nbsp;</td>
  </tr>
  <tr>
    <td valign="top">
    <p><code>path(&quot;/&quot;)<br>
&nbsp;.is_absolute()<br>
    path(&quot;c:/&quot;)<br>
&nbsp;.is_absolute()</code></td>
    <td valign="top">
    <p>[<a href="#path-query">path</a><br>
&nbsp;<a href="#path-query">.query</a>]</td>
    <td valign="top">
    <p><code><br>
    true<br>
    <br>
    false</code></td>
    <td valign="top">
    <p><code><br>
    false<br>
    <br>
    true</code></td>
    <td valign="top">
    <p>&nbsp;</td>
  </tr>
  <tr>
    <td valign="top">
    <p><code>path</code> argument disambiguation between generic format and 
    native format</td>
    <td valign="top">
    <p>[<a href="#path-Conversions-to-native-format">path.arg</a><br>
&nbsp;<a href="#path-Conversions-to-native-format">.fmt.cvt</a>]</td>
    <td valign="top">
    <p>Not required</td>
    <td valign="top">
    <p>Not required</td>
    <td valign="top">
    <p>There is no need to distinguish between the generic format and native 
    format for these operating systems.</td>
  </tr>
  <tr>
    <td valign="top">
    <p><code>path</code> argument format conversion</td>
    <td valign="top">
    <p>[<a href="#path-Conversions-to-native-format">path.arg</a><br>
&nbsp;<a href="#path-Conversions-to-native-format">.fmt.cvt</a>]</td>
    <td valign="top">
    <p>No conversion performed</td>
    <td valign="top">
    <p>No conversion performed</td>
    <td valign="top">
    <p>The generic format is already acceptable to the native API of these operating systems.</td>
  </tr>
  <tr>
    <td valign="top">
    <p><code>path<br>
&nbsp;(&quot;/cats/jane&quot;)<br>
&nbsp;.c_str()<br>
    path|<br>
&nbsp;(&quot;/cats/jane/&quot;)<br>
&nbsp;.c_str()</code></td>
    <td valign="top">
    <p>[<a href="#path-Conversions-to-native-format">path.arg</a><br>
&nbsp;<a href="#path-Conversions-to-native-format">.fmt.cvt</a>]</td>
    <td valign="top"> 
    <p> <code><br>
    <br>
    &quot;/cats/jane&quot;<br>
    <br>
    <br>
    &quot;/cats/jane/&quot;</code></td>
    <td valign="top">
    <p><code><br>
    <br>
    L&quot;/cats/jane&quot;<br>
    <br>
    <br>
    L&quot;/cats/jane/&quot;</code></td>
    <td valign="top">
    <p>These operating systems accept the same native separator between 
    directory names and a final file name, so no format conversion is performed. 
    Other operating systems might require conversion.</td>
  </tr>
  <tr>
    <td valign="top">
    <p>Format conversion by <code>path</code> native format observers</td>
    <td valign="top">
    <p>[<a href="#path-native-format-observers">path.native</a><br>
&nbsp;<a href="#path-native-format-observers">.obs</a>]</td>
    <td valign="top">
    <p>No conversion performed</td>
    <td valign="top">
    <p>No conversion performed</td>
    <td valign="top">
    <p>For efficiency, <code>path</code> objects are required to store pathnames in the native 
    format regardless of operating system.</td>
  </tr>
  <tr>
    <td valign="top">
    <p>Format conversion by <code>path</code> generic format observers</td>
    <td valign="top">
    <p>[<a href="#path-generic-format-observers">path</a><br>
&nbsp;<a href="#path-generic-format-observers">.generic</a><br>
&nbsp;<a href="#path-generic-format-observers">.obs</a>]</td>
    <td valign="top">
    <p>No conversion performed</td>
    <td valign="top">
    <p>Backslashes converted to slashes</td>
    <td valign="top">
    <p>&nbsp;</td>
  </tr>
  <tr>
    <td valign="top">
    <p><code>p.<br>
&nbsp;make_preferred()</code></td>
    <td valign="top">
    <p>[<a href="#path-modifiers">fs.path</a><br>
&nbsp;<a href="#path-modifiers">.modifiers</a>]</td>
    <td valign="top">
    <p>No change</td>
    <td valign="top">
    <p>Slashes converted to backslashes</td>
    <td valign="top">
    <p>&nbsp;</td>
  </tr>
  <tr>
    <td valign="top">
    <p>Characters prohibited in filenames</td>
    <td valign="top">
    <p>[<a href="#filename">fs.def</a><br>
&nbsp;<a href="#filename">.filename</a>]</td>
    <td valign="top">
    <p>0x00, <code>'/'</code></td>
    <td valign="top">
    <p>0x00-0x1F, <code>'&quot;'</code>, <code>'*'</code>,<code>&nbsp;'*'</code>, 
    <code>'&lt;'</code>, 
    <code>'&gt;'</code>, <code>'?'</code>, <code>'\\'</code> (single backslash), 
    <code>'/'</code>, <code>'|'</code></td>
    <td valign="top">
    <p>Many operating systems prohibit the ASCII control characters (0x00-0x1F) 
    in filenames.</td>
  </tr>
  <tr>
    <td valign="top">
    <p>Initial imbued <code>path</code> locale</td>
    <td valign="top">
    <p>[<a href="#path-imbued-locale">path</a><br>
&nbsp;<a href="#path-imbued-locale">.imbued</a><br>
&nbsp;<a href="#path-imbued-locale">.locale</a>]</td>
    <td valign="top"> 
    <p> <code>std::<br>
&nbsp; locale(&quot;&quot;)<br>
    </code><sup>[footnote 2]</sup></td>
    <td valign="top">
    <p>Implementation supplied locale using <code>MultiByte<br>
&nbsp; ToWideChar</code> 
    and <code>WideChar<br>
&nbsp; ToMultiByte</code> with a codepage of <code>CP_ACP</code> 
    if <code>AreFileApisANSI</code> is true, otherwise codepage <code>CP_OEMCP</code>.<sup>[footnote 
    3]</sup></td>
    <td valign="top">
    <p>Apple OS X&reg;:&nbsp; Implementation supplied locale providing UTF-8 <code>codecvt</code> 
    facet.<sup>[footnote 4]</sup></td>
  </tr>
</table>
<p><sup>[footnote1]</sup> OS X&reg; and Windows&reg; are examples of commercially 
available operating systems. This information is given for the convenience of 
users of this document and does not constitute an endorsement by ISO or IEC of 
these products.</p>
<p><sup>[footnote 2] </sup>Rationale: ISO C specifies <code>std::locale(&quot;&quot;)</code> as &quot;the locale-specific native 
environment&quot;, while ISO/IEC 9945 says it &quot;Specifies an implementation-defined native 
environment.&quot;</p>
<p><sup>[footnote 3] </sup>Rationale: This is the current behavior of C and C++ 
standard library functions that perform file operations using narrow character 
strings to identify paths. Changing this behavior would be surprising and at 
variance with existing code, particularly where user input is involved.</p>
<p><sup>[footnote 4]</sup> Rationale: Vendor's documentation states &quot;All BSD 
system functions expect their string parameters to be in UTF-8 encoding and 
nothing else.&quot;</p>
<h2><a name="Header-filesystem-synopsis">Header <code>&lt;boost/filesystem.hpp&gt;</code> synopsis</a> 
[filesystem.synopsis]</h2>



<pre>namespace boost
{
  namespace filesystem
  {
    class <a href="#class-path">path</a>;
    
    bool lexicographical_compare(path::iterator first1, path::iterator last1,
      path::iterator first2, path::iterator last2);
    void swap(path&amp; lhs, path&amp; rhs);
    std::size_t <a href="#hash_value">hash_value</a>(const path&amp; p);

    bool operator==(const path&amp; lhs, const path&amp; rhs);
    bool operator!=(const path&amp; lhs, const path&amp; rhs);
    bool operator&lt; (const path&amp; lhs, const path&amp; rhs);
    bool operator&lt;=(const path&amp; lhs, const path&amp; rhs);
    bool operator&gt; (const path&amp; lhs, const path&amp; rhs);
    bool operator&gt;=(const path&amp; lhs, const path&amp; rhs);

    path operator/ (const path&amp; lhs, const path&amp; rhs);
    
    std::ostream&amp;  operator&lt;&lt;( std::ostream&amp; os, const path&amp; p );
    std::wostream&amp; operator&lt;&lt;( std::wostream&amp; os, const path&amp; p );
    std::istream&amp;  operator&gt;&gt;( std::istream&amp; is, path&amp; p );
    std::wistream&amp; operator&gt;&gt;( std::wistream&amp; is, path&amp; p )

    class <a href="#Class-filesystem_error">filesystem_error</a>;      
    class <a href="#Class-directory_entry">directory_entry</a>;

    class <a href="#Class-directory_iterator">directory_iterator</a>;

    // enable c++11 range-based for statements
    const directory_iterator&amp; <a href="#directory_iterator-non-member-functions">begin</a>(const directory_iterator&amp; iter);
    directory_iterator <a href="#directory_iterator-non-member-functions">end</a>(const directory_iterator&amp;);


    // enable BOOST_FOREACH
    directory_iterator&amp; range_begin(directory_iterator&amp; iter);
    directory_iterator range_begin(const directory_iterator&amp; iter);
    directory_iterator range_end(const directory_iterator&amp;);

    class <a href="#Class-recursive_directory_iterator">recursive_directory_iterator</a>;

    // enable c++11 range-based for statements
    const recursive_directory_iterator&amp;
      <a href="#recursive_directory_iterator-non-member-functions">begin</a>(const recursive_directory_iterator&amp; iter);
    recursive_directory_iterator
      <a href="#recursive_directory_iterator-non-member-functions">end</a>(const recursive_directory_iterator&amp;);


    // enable BOOST_FOREACH
    recursive_directory_iterator&amp;
      range_begin(recursive_directory_iterator&amp; iter);
    recursive_directory_iterator
      range_begin(const recursive_directory_iterator&amp; iter);
    recursive_directory_iterator
      range_end(const recursive_directory_iterator&amp;);

    enum <a name="file_type" href="#Enum-file_type">file_type</a>
    {
      status_error, file_not_found, regular_file, directory_file,
      symlink_file, block_file, character_file, fifo_file, socket_file,
      type_unknown
    };

    enum <a href="#Enum-perms">perms</a>
    {
      no_perms,
      owner_read, owner_write, owner_exe, owner_all,
      group_read, group_write, group_exe, group_all,
      others_read, others_write, others_exe, others_all, all_all,
      set_uid_on_exe, set_gid_on_exe, sticky_bit,
      perms_mask, perms_not_known,
      add_perms, remove_perms, symlink_perms
    };

    class <a href="#file_status">file_status</a>;

    struct <a name="space_info">space_info</a>  // returned by <a href="#space" style="text-decoration: none">space</a> function
    {
      uintmax_t capacity;
      uintmax_t free; 
      uintmax_t available; // free space available to non-privileged process
    };

    enum class <a name="copy_option">copy_option</a>
    {
      none
      fail_if_exists = none,
      overwrite_if_exists
    };

    enum class <a name="symlink_option">symlink_option</a>
    {
      none
      no_recurse = none,
      recurse
    };

    // <a href="#Operational-functions">operational functions</a>

    path         <a href="#absolute">absolute</a>(const path&amp; p, const path&amp; base=current_path());

    path         <a href="#canonical">canonical</a>(const path&amp; p, const path&amp; base = current_path());
    path         <a href="#canonical">canonical</a>(const path&amp; p, system::error_code&amp; ec);
    path         <a href="#canonical">canonical</a>(const path&amp; p, const path&amp; base,
                   system::error_code&amp; ec);

    void         <a href="#copy">copy</a>(const path&amp; from, const path&amp; to);
    void         <a href="#copy">copy</a>(const path&amp; from, const path&amp; to,
                   system::error_code&amp; ec);

    void         <a href="#create_directory">copy_directory</a>(const path&amp; from, const path&amp; to);
    void         <a href="#create_directory">copy_directory</a>(const path&amp; from, const path&amp; to,
                   system::error_code&amp; ec);

    void         <a href="#copy_file">copy_file</a>(const path&amp; from, const path&amp; to);
    void         <a href="#copy_file">copy_file</a>(const path&amp; from, const path&amp; to,
                   system::error_code&amp; ec);
    void         <a href="#copy_file">copy_file</a>(const path&amp; from, const path&amp; to,
                   <a href="#copy_option">copy_option</a> option);
    void         <a href="#copy_file">copy_file</a>(const path&amp; from, const path&amp; to,
                   <a href="#copy_option">copy_option</a> option, system::error_code&amp; ec);

    void         <a href="#copy_symlink">copy_symlink</a>(const path&amp; existing_symlink,
                   const path&amp; new_symlink);
    void         <a href="#copy_symlink">copy_symlink</a>(const path&amp; existing_symlink,
                   const path&amp; new_symlink, system::error_code&amp; ec);

    bool         <a href="#create_directories">create_directories</a>(const path&amp; p);
    bool         <a href="#create_directories">create_directories</a>(const path&amp; p,
                   system::error_code&amp; ec);

    bool         <a href="#create_directory">create_directory</a>(const path&amp; p);
    bool         <a href="#create_directory">create_directory</a>(const path&amp; p, system::error_code&amp; ec);

    void         <a href="#create_directory_symlink">create_directory_symlink</a>(const path&amp; to,
                   const path&amp; new_symlink);
    void         <a href="#create_directory_symlink">create_directory_symlink</a>(const path&amp; to,
                   const path&amp; new_symlink, system::error_code&amp; ec);

    void         <a href="#create_hard_link">create_hard_link</a>(const path&amp; to, const path&amp; new_hard_link);
    void         <a href="#create_hard_link">create_hard_link</a>(const path&amp; to, const path&amp; new_hard_link,
                                  system::error_code&amp; ec);

    void         <a href="#create_symlink">create_symlink</a>(const path&amp; to, const path&amp; new_symlink);
    void         <a href="#create_symlink">create_symlink</a>(const path&amp; to, const path&amp; new_symlink,
                                system::error_code&amp; ec);

    path         <a href="#current_path">current_path</a>();
    path         <a href="#current_path">current_path</a>(system::error_code&amp; ec);
    void         <a href="#current_path">current_path</a>(const path&amp; p);
    void         <a href="#current_path">current_path</a>(const path&amp; p, system::error_code&amp; ec);

    bool         <a href="#exists">exists</a>(file_status s) noexcept;
    bool         <a href="#exists">exists</a>(const path&amp; p);
    bool         <a href="#exists">exists</a>(const path&amp; p, system::error_code&amp; ec) noexcept;

    bool         <a href="#equivalent">equivalent</a>(const path&amp; p1, const path&amp; p2);
    bool         <a href="#equivalent">equivalent</a>(const path&amp; p1, const path&amp; p2,
                   system::error_code&amp; ec);

    uintmax_t    <a href="#file_size">file_size</a>(const path&amp; p);
    uintmax_t    <a href="#file_size">file_size</a>(const path&amp; p, system::error_code&amp; ec);

    uintmax_t    <a href="#hard_link_count">hard_link_count</a>(const path&amp; p);
    uintmax_t    <a href="#hard_link_count">hard_link_count</a>(const path&amp; p, system::error_code&amp; ec);

    const path&amp;  <a href="#initial_path">initial_path</a>();
    const path&amp;  <a href="#initial_path">initial_path</a>(<code>system::error_code&amp; ec</code>);

    bool         <a href="#is_directory">is_directory</a>(file_status s) noexcept;
    bool         <a href="#is_directory2">is_directory</a>(const path&amp; p);
    bool         <a href="#is_directory2">is_directory</a>(const path&amp; p,
                   system::error_code&amp; ec) noexcept;

    bool         <a href="#is_empty">is_empty</a>(const path&amp; p);
    bool         <a href="#is_empty">is_empty</a>(const path&amp; p, system::error_code&amp; ec);

    bool         <a href="#is_other">is_other</a>(file_status s) noexcept;
    bool         <a href="#is_other2">is_other</a>(const path&amp; p,);
    bool         <a href="#is_other2">is_other</a>(const path&amp; p, system::error_code&amp; ec) noexcept;

    bool         <a href="#is_regular_file">is_regular_file</a>(file_status s) noexcept; 
    bool         i<a href="#is_regular_file2">s_regular_file</a>(const path&amp; p);
    bool         i<a href="#is_regular_file2">s_regular_file</a>(const path&amp; p,
                   system::error_code&amp; ec) noexcept;

    bool         <a href="#is_symlink">is_symlink</a>(file_status s noexcept);
    bool         <a href="#is_symlink2">is_symlink</a>(const path&amp; p);
    bool         <a href="#is_symlink2">is_symlink</a>(const path&amp; p, system::error_code&amp; ec) noexcept;

    std::time_t  <a href="#last_write_time">last_write_time</a>(const path&amp; p);
    std::time_t  <a href="#last_write_time">last_write_time</a>(const path&amp; p, system::error_code&amp; ec);
    void         <a href="#last_write_time2">last_write_time</a>(const path&amp; p, const std::time_t new_time);
    void         <a href="#last_write_time2">last_write_time</a>(const path&amp; p, const std::time_t new_time,
                                 system::error_code&amp; ec);

    path         <a href="#read_symlink">read_symlink</a>(const path&amp; p);
    path         <a href="#read_symlink">read_symlink</a>(const path&amp; p, system::error_code&amp; ec);
    
    <span style="background-color: #E8FFE8">path         </span><span style="background-color: #E8FFE8">relative(const</span><span style="background-color: #E8FFE8"> path&amp; p, </span><span style="background-color: #E8FFE8">system::error_code</span><span style="background-color: #E8FFE8">&amp; </span><span style="background-color: #E8FFE8">ec</span><span style="background-color: #E8FFE8">);</span>
    <span style="background-color: #E8FFE8">path         </span><span style="background-color: #E8FFE8">relative(const</span><span style="background-color: #E8FFE8"> path&amp; p, const path&amp; base=</span><span style="background-color: #E8FFE8">current_path</span><span style="background-color: #E8FFE8">());</span>
    <span style="background-color: #E8FFE8">path         </span><span style="background-color: #E8FFE8">relative(const</span><span style="background-color: #E8FFE8"> path&amp; p,</span>
                     <span style="background-color: #E8FFE8">const path&amp; base, </span><span style="background-color: #E8FFE8">system::error_code</span><span style="background-color: #E8FFE8">&amp; </span><span style="background-color: #E8FFE8">ec</span><span style="background-color: #E8FFE8">);</span>

    bool         <a href="#remove">remove</a>(const path&amp; p);
    bool         <a href="#remove">remove</a>(const path&amp; p, system::error_code&amp; ec);

    uintmax_t    <a href="#remove_all">remove_all</a>(const path&amp; p);
    uintmax_t    <a href="#remove_all">remove_all</a>(const path&amp; p, system::error_code&amp; ec);

    void         <a href="#rename">rename</a>(const path&amp; from, const path&amp; to);
    void         <a href="#rename">rename</a>(const path&amp; from, const path&amp; to,
                   system::error_code&amp; ec);

    void         <a href="#resize_file">resize_file</a>(const path&amp; p, uintmax_t size);
    void         <a href="#resize_file2">resize_file</a>(const path&amp; p, uintmax_t size,
                   system::error_code&amp; ec);

    <a href="#space_info">space_info</a>   <a href="#space">space</a>(const path&amp; p);
    <a href="#space_info">space_info</a>   <a href="#space">space</a>(const path&amp; p, system::error_code&amp; ec);

    <a href="#file_status">file_status</a>  <a href="#status">status</a>(const path&amp; p);
    <a href="#file_status">file_status</a>  <a href="#status">status</a>(const path&amp; p, system::error_code&amp; ec) noexcept;

    bool         <a href="#status_known">status_known</a>(file_status s) noexcept;

    <a href="#file_status">file_status</a>  <a href="#symlink_status">symlink_status</a>(const path&amp; p);
    <a href="#file_status">file_status</a>  <a href="#symlink_status">symlink_status</a>(const path&amp; p,
                   system::error_code&amp; ec) noexcept;

    path         <a href="#system_complete">system_complete</a>(const path&amp; p);
    path         <a href="#system_complete">system_complete</a>(const path&amp; p, system::error_code&amp; ec);

    path         <a href="#temp_directory_path">temp_directory_path</a>();
    path         <a href="#temp_directory_path">temp_directory_path</a>(system::error_code&amp; ec);

    path         <a href="#unique_path">unique_path</a>(const path&amp; model=&quot;%%%%-%%%%-%%%%-%%%%&quot;);
    path         <a href="#unique_path">unique_path</a>(const path&amp; model, system::error_code&amp; ec);

    <span style="background-color: #E8FFE8">path         </span><span style="background-color: #E8FFE8">weakly_canonical(const</span><span style="background-color: #E8FFE8"> path&amp; p);</span>
    <span style="background-color: #E8FFE8">path         </span><span style="background-color: #E8FFE8">weakly_canonical(const</span><span style="background-color: #E8FFE8"> path&amp; p, </span><span style="background-color: #E8FFE8">system::error_code</span><span style="background-color: #E8FFE8">&amp; </span><span style="background-color: #E8FFE8">ec</span><span style="background-color: #E8FFE8">);</span>

  }  // namespace filesystem
}  // namespace boost</pre>



<h2><a name="Error-reporting">Error reporting</a> [fs.err.report]</h2>
<p>Filesystem library functions often provide two overloads, one that 
throws an exception to report file system errors, and another that sets an <code>error_code</code>.</p>
<blockquote>
<p>[<i>Note:</i> This supports two common use cases:</p>
<ul>
  <li>
  <p>Uses where file system 
errors are truly exceptional and indicate a serious failure. Throwing an 
  exception is the most appropriate response. This is the preferred default for 
  most everyday programming.<br>
&nbsp;</li>
  <li>
  <p>Uses where file system system errors are routine and do not necessarily represent 
  failure. Returning an error code is the most appropriate response. This allows 
  application specific error handling, including simply ignoring the error.</li>
</ul>
  <p><i>—end note</i>]</p>
</blockquote>
<p>Functions <b>not</b> having an argument of type <code>system::error_code&amp;</code> report errors as follows, unless otherwise specified:</p>
  <ul>
  <li>
  <p>When a call by the 
  implementation to an operating system or other underlying API results in an 
  error that prevents the function from meeting its specifications, an exception 
  of type
<code>filesystem_error</code> is thrown.<br>
&nbsp;</li>
  <li>
  <p>Failure to allocate storage is reported by throwing an exception as described in the C++ standard, 
  17.6.4.10 [res.on.exception.handling].<br>
&nbsp;</li>
  <li>
  <p>Destructors throw nothing.</li>
  </ul>
  <p>Functions having an argument of type <code>system::error_code&amp;</code> report errors as follows, unless otherwise 
  specified:</p>
<ul>
  <li>
  <p>If a call by the 
  implementation to an operating system or other underlying API results in an 
  error that prevents the function from meeting its specifications, the
<code>system::error_code&amp;</code> argument is set as 
  appropriate appropriate for the specific error. Otherwise, <code>clear()</code> 
  is called on the
<code>system::error_code&amp;</code> argument.<br>
&nbsp;</li>
  <li>
  <p>Failure to allocate storage is reported by 
  throwing an exception as described in the C++ standard, 
  17.6.4.10 [res.on.exception.handling].</li>
</ul>
<h2><a name="class-path">Class <code>path</code> [class.path]</a></h2>
<p>An object of class <code>path</code> represents a <a href="#path">path</a>, 
and contains a <a href="#pathname">pathname</a> Such an object is concerned only with the lexical and syntactic aspects 
of a path. The path does not necessarily exist in external storage, and the 
pathname is not necessarily valid for the current operating 
system or for a particular file system.</p>

<div dir="ltr">

<pre>namespace boost
{
  namespace filesystem
  {
      class path
      {
      public:
        typedef <b><i><a href="#value_type">see below</a></i></b>                                    value_type;
        typedef std::basic_string&lt;value_type&gt;                string_type;
        typedef std::codecvt&lt;wchar_t, char, std::mbstate_t&gt;  codecvt_type;
        constexpr value_type                                 dot;
        constexpr value_type                                 separator;
        constexpr value_type                                 preferred_separator;

        // <a href="#path-constructors">constructors</a> and destructor
        path();
        path(const path&amp; p);
        path(path&amp;&amp; p) noexcept;

        template &lt;class <a href="#Source">Source</a>&gt;
          path(Source const&amp; source, const codecvt_type&amp; cvt=codecvt());

        template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
          path(InputIterator begin, InputIterator end,
            const codecvt_type&amp; cvt=codecvt());

       ~path();

        // <a href="#path-assignments">assignments</a>
        path&amp; operator=(const path&amp; p);
        path&amp; operator=(path&amp;&amp; p) noexcept;

        template &lt;class <a href="#Source">Source</a>&gt;
          path&amp; operator=(Source const&amp; source);

        template &lt;class <a href="#Source">Source</a>&gt;
          path&amp; assign(Source const&amp; source, const codecvt_type&amp; cvt)

        template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
          path&amp; assign(InputIterator begin, InputIterator end,
            const codecvt_type&amp; cvt=codecvt());

        // <a href="#path-appends">appends</a>
        path&amp; operator/=(const path&amp; p);

        template &lt;class <a href="#Source">Source</a>&gt;
          path&amp; operator/=(Source const&amp; source);

        template &lt;class <a href="#Source">Source</a>&gt;
          path&amp; append(Source const&amp; source, const codecvt_type&amp; cvt);

        template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
          path&amp; append(InputIterator begin, InputIterator end,
            const codecvt_type&amp; cvt=codecvt());

        // <a href="#path-concatenation">concatenation</a>
        path&amp; operator+=(const path&amp; x);
        path&amp; operator+=(const string_type&amp; x);
        path&amp; operator+=(const value_type* x);
        path&amp; operator+=(value_type x);
        template &lt;class Source&gt;
          path&amp; operator+=(Source const&amp; x);
        template &lt;class CharT&gt;
          path&amp; operator+=(CharT x);
        template &lt;class Source&gt;
          path&amp; concat(Source const&amp; x, const codecvt_type&amp; cvt);
        template &lt;class InputIterator&gt;
          path&amp; concat(InputIterator begin, InputIterator end);
        template &lt;class InputIterator&gt;
          path&amp; concat(InputIterator begin, InputIterator end,
            const codecvt_type&amp; cvt);
        
        // <a href="#path-modifiers">modifiers</a>
        void  <a href="#path-clear">clear</a>();
        path&amp; <a href="#path-make_preferred">make_preferred</a>();
        path&amp; <a href="#path-remove_filename">remove_filename</a>();
        path&amp; <a href="#path-replace_extension">replace_extension</a>(const path&amp; new_extension = path());
        void  <a href="#path-swap">swap</a>(path&amp; rhs);

        // lexical operations
        <span style="background-color: #E8FFE8">path </span><span style="background-color: #E8FFE8">lexically_normal</span><span style="background-color: #E8FFE8">() const;</span>
        <span style="background-color: #E8FFE8">path </span><span style="background-color: #E8FFE8">lexically_relative(const</span><span style="background-color: #E8FFE8"> path&amp; base) const;</span>

        // <a href="#path-native-format-observers">native format observers</a>
        const string_type&amp;  <a href="#native">native</a>() const noexcept;  // native format, encoding
        const value_type*   <a href="#c_str">c_str</a>() const noexcept;   // native().c_str()
        <span style="background-color: #E8FFE8">string_type::size_type</span><span style="background-color: #E8FFE8"> </span><a href="#path-size"><span style="background-color: #E8FFE8">size</span></a><span style="background-color: #E8FFE8">() const noexcept; // </span><span style="background-color: #E8FFE8">native().size</span><span style="background-color: #E8FFE8">()</span>

        template &lt;class String&gt;
          String  <a href="#string-template">string</a>(const codecvt_type&amp; cvt=codecvt()) const;
        string    <a href="#string">string</a>(const codecvt_type&amp; cvt=codecvt()) const;
        wstring   <a href="#wstring">wstring</a>(const codecvt_type&amp; cvt=codecvt()) const;
        u16string <a href="#u16string">u16string</a>() const;
        u32string <a href="#u32wstring">u32string</a>() const;

        // <a href="#path-generic-format-observers">generic format observers</a>
        template &lt;class String&gt;
          String  <a href="#generic_string-template">generic_string</a>() const;

        string    <a href="#generic_string">generic_string</a>(const codecvt_type&amp; cvt=codecvt()) const; 
        wstring   <a href="#generic_wstring">generic_wstring</a>(const codecvt_type&amp; cvt=codecvt()) const;
        u16string <a href="#generic_u16string">generic_u16string</a>()
        u32string <a href="#generic_u32wstring">generic_u32string</a>()

        // <a href="#path-compare">compare</a>
        int   <a href="#path-compare">compare</a>(const path&amp; p) const noexcept;
        int   <a href="#path-compare">compare</a>(const std::string&amp; s) const;
        int   <a href="#path-compare">compare</a>(const value_type* s) const;

        // <a href="#path-decomposition">decomposition</a>
        path  <a href="#path-root_name">root_name</a>() const;
        path  <a href="#path-root_directory">root_directory</a>() const;
        path  <a href="#path-root_path">root_path</a>() const;
        path  <a href="#path-relative_path">relative_path</a>() const;
        path  <a href="#path-parent_path">parent_path</a>() const;
        path  <a href="#path-filename">filename</a>() const;
        path  <a href="#path-stem">stem</a>() const;
        path  <a href="#path-extension">extension</a>() const;

        // <a href="#path-query">query</a>
        bool <a href="#path-query">empty</a>() const;
        <span style="background-color: #CCFFCC">bool <a href="#filename_is_dot">filename_is_dot</a>() const;</span>
        <span style="background-color: #CCFFCC">bool <a href="#filename_is_dot­_dot">filename_is_dot_dot</a>() const;</span>
        bool <a href="#path-has_root_name">has_root_name</a>() const;
        bool <a href="#path-has_root_directory">has_root_directory</a>() const;
        bool <a href="#path-has_root_path">has_root_path</a>() const;
        bool <a href="#path-has_relative_path">has_relative_path</a>() const;
        bool <a href="#path-has_parent_path">has_parent_path</a>() const;
        bool <a href="#path-has_filename">has_filename</a>() const;
        bool <a href="#path-has_stem">has_stem</a>() const;
        bool <a href="#path-has_extension">has_extension</a>() const;
        bool <a href="#path-is_absolute">is_absolute</a>() const;
        bool <a href="#path-is_relative">is_relative</a>() const;

        // <a href="#path-iterators">iterators</a>
        class iterator;
        typedef iterator const_iterator;
        class reverse_iterator;
        typedef reverse_iterator const_reverse_iterator;

        iterator begin() const;
        iterator end() const;
        reverse_iterator rbegin() const;
        reverse_iterator rend() const;
        
        // <a href="#path-imbued-locale">imbued locale</a>
        static std::locale <a href="#path-imbue">imbue</a>(const std::locale&amp; loc);
        static const codecvt_type &amp; <a href="#path-codecvt">codecvt</a>();

      private:
        string_type pathname;  // <b><i>exposition only</i></b>
      };

  }  // namespace filesystem
}  // namespace boost</pre>

</div>

<p><code><a name="value_type">value_type</a></code> is a <code>typedef</code> for the 
character type used by the operating system to represent pathnames.</p>


<h3><a name="path-Usage"><code>path</code> Usage concerns</a> [path.usage]</h3>

<h4>Multithreading concerns</h4>

<p>Filesystem library functions are not protected against data races. [Modifying 
an object of a Filesystem library type that is shared between threads risks 
undefined behavior unless objects of that type are explicitly specified as being 
sharable without data races or the user supplies a locking mechanism. <i>—end 
note</i>] [<i>Note:</i> Thus the Filesystem library behaves as if it were part 
of the standard library, and C++ standard 17.6.4.10 <i>Shared objects and the 
library</i> [res.on.objects] would thus apply.&nbsp; <i>—end note</i>]</p>

<h4>Windows concerns</h4>

<p>Visual C++ at least through version 2012 does not employ C++11-style static 
initialization locks, so the initialization of <code>path::codecvt()</code> can 
race, either with itself or <code>path::imbue::()</code> if they are called from 
a different thread. A workaround is to call:</p>

<blockquote>
<p><code>path::codecvt();&nbsp; // ensure VC++ does not race during 
initialization.</code></p>

</blockquote>
<p>in the main thread before launching any additional threads. [<i>Note:</i> The 
obvious fix of the Filesystem implementation doing the locking doesn't work 
because of unrelated problems with the Microsoft compiler; for static linking 
the runtime tries to do the initialization before main() starts, but doesn't 
permit operating system lock calls at that time.&nbsp; <i>—end note</i>]</p>

<h4>POSIX concerns</h4>

<p>Filesystem library initialization may throw an exception on POSIX 
systems (e.g. Linux, but not Mac OS X) that use environmental variables to 
determine the encoding of paths. This happens when <code>std::locale(&quot;&quot;)</code> 
throws because an environmental variable such as LANG is set to an invalid 
value, so it can affect any use of&nbsp; <code>std::locale(&quot;&quot;)</code>, not just 
the Filesystem library. Filesystem uses lazy initialization so the exception is 
only thrown if a valid <code>std::locale(&quot;&quot;)</code> is actually needed, and also 
so that the exception is thrown after <code>main()</code> starts.</p>

<p>Rather than waiting until a call to some Filesystem library function 
unexpectedly triggers the exception when it calls <code>path::codecvt()</code>, 
a program that needs be highly robust against environmental variable problems 
may want to preemptively call <code>std::locale(&quot;&quot;)</code> within a try block, 
catch the exception, and diagnose or repair the invalid environmental variable.</p>

<h3><a name="path-Conversions"><code>path</code> Conversions</a> [path.cvt]</h3>
<h4><code>path</code> argument conversions [<a name="path.arg.convert">path.arg.cvt</a>]</h4>
<h5><a name="path-Conversions-to-native-format"><code>path</code> argument 
format conversions</a> [path.arg.fmt.cvt]</h5>
<p>Member function arguments that take character sequences representing paths 
may use the <a href="#generic-pathname-format">generic pathname format</a> or 
the <a href="#native-pathname-format">native pathname format</a>. Iff such  arguments 
are in the generic format and the generic format is not acceptable to the 
operating system as a native path,  conversion to native format shall be performed 
during the processing of the argument. See [<a href="#Operating-system-examples">fs.os.examples</a>].</p>
<blockquote>
<p>[<i>Note:</i> Depending on the operating system, there may be no unambiguous way for an implementation to 
always be able to distinguish between native format and generic format arguments. 
This is by design as it simplifies use for operating systems that do not require 
disambiguation. Should an implementation encounter an 
operating system where disambiguation is required, an implementation can defined 
an extension to distinguish between the formats. <i>
—end note</i>]</p>
</blockquote>

<p>If the native format requires 
paths for regular files to be formatted differently from paths for directories, the 
path shall be treated as a directory path if last element is a separator, 
otherwise it shall be treated as a regular file path.</p>

<h5><a name="path-Encoding-conversions"><code>
path</code> argument encoding conversions</a> 
[path.arg.encoding.cvt]</h5>
<p>For member function arguments that take character sequences representing 
paths, if the value type of the argument is not <code>value_type and </code>one 
of the value types is <code>char</code> and the other is <code>wchar_t</code>, conversion to <code>value_type</code> 
shall be performed by the <code>path::codecvt()</code> facet. ([<a href="#path-imbued-locale">path.imbued.locale</a>]).</p>
<h4><a name="path-Conversions-to-generic-format"><code>path</code> Conversions 
to generic format</a> [fs.cvt.to.generic]</h4>
<p><a href="#path-generic-format-observers">Generic format observer</a> functions 
shall return strings formatted according to the <a href="#generic-pathname-format">generic pathname format</a> 
using <i>preferred-separator</i>. See [<a href="#Operating-system-examples">fs.os.examples</a>].</p>
<h3><a name="path-Requirements"><code>path</code> Requirements</a> [path.req]</h3>
<p>Template parameters named <code><a name="InputIterator">InputIterator</a></code> are required meet the 
requirements for a C++ standard library <code>RandomIterator</code> compliant iterator. The iterator's value type is required to be <code>char</code>, <code>wchar_t</code>, <code>char16_t</code>, or <code>char32_t</code>.</p>
<p>Template parameters named <code><a name="Source">Source</a></code> are required to be one of:</p>
<ul>
  <li>
  <p>A container with a value type of <code>char</code>, <code>
  wchar_t</code>, <code>char16_t</code>, or <code>char32_t</code>.</li>
  <li>
  <p>An iterator for a null terminated byte-string. The value type is required 
  to be <code>char</code>, <code>wchar_t</code>, <code>char16_t</code>, or <code>
  char32_t</code>.</li>
  <li>
  <p>A C-array. The value type is required to be <code>char</code>, <code>
  wchar_t</code>, <code>char16_t</code>, or <code>char32_t</code>.</li>
  <li>
  <p>A <code>boost::filesystem::directory_entry</code>.</li>
</ul>

<h3> <a name="path-constructors"> <code>
<font size="4">path</font></code> constructors</a> [path.construct]</h3>

<pre>template &lt;class <a href="#Source">Source</a>&gt;
  path(Source const&amp; source, const codecvt_type&amp; cvt=codecvt());</pre>


<pre>template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
  path(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt=codecvt());</pre>

<blockquote>
  <p><i>Effects:</i> Stores the contents [<code>begin</code>,<code>end</code>) 
  or <code>source</code> in <code>pathname</code>, converting format and 
  encoding if required ([<a href="#path.arg.convert">path.arg.convert</a>]).</p>
</blockquote>
<h3> <a name="path-assignments"> <code>
<font size="4">path</font></code> assignments</a> [path.assign]</h3>

<pre>template &lt;class <a href="#Source">Source</a>&gt;
  path&amp; operator=(Source const&amp; source);
  template &lt;class <a href="#Source">Source</a>&gt;
  path&amp; assign(Source const&amp; source, const codecvt_type&amp; cvt);
  template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
  path&amp; assign(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt=codecvt());</pre>

<blockquote>
  <p><i>Effects:</i> Stores the contents [<code>begin</code>,<code>end</code>) 
  or <code>source</code> in <code>pathname</code>, converting format and 
  encoding if required ([<a href="#path.arg.convert">path.arg.convert</a>]). </p>
  <p>
  <i>Returns: </i><code>*this</code></p>
  </blockquote>
<h3><a name="path-appends"><code><font size="4"> path</font></code> appends</a> 
[path.append]</h3>
  <p>The append operations use <code>
  operator/=</code> to denote their semantic effect of appending <i>
  preferred-separator</i> when needed. </p>

<pre>path&amp; operator/=(const path&amp; p);</pre>

<blockquote>
  <p><i>Effects:</i></p>
  <blockquote>
    <p>Appends <code>path::preferred_separator</code> to <code>pathname</code>, 
    converting format and encoding if required ([<a href="#path.arg.convert">path.arg.convert</a>]), unless:</p>
    <ul>
    <li>
    <p>an added separator 
    would be redundant, or</li>
    <li>
    <p>would change an relative path to an absolute path, or</li>
    <li>
    <p><code>p.empty()</code>, or</li>
    <li>
    <p><code>*p.native().cbegin()</code> is a directory separator.</li>
  </ul>
    <p>Then appends <code>p.native()</code> to <code>pathname</code>.</p>
  </blockquote>
  <p><i>Returns: </i><code>*this</code></p>
</blockquote>

<pre>template &lt;class <a href="#Source">Source</a>&gt;
  path&amp; operator/=(Source const &amp; source);
  template &lt;class <a href="#Source">Source</a>&gt;
  path&amp; append(Source const &amp; source, const codecvt_type&amp; cvt);
  template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
  path&amp; append(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt=codecvt());</pre>

<blockquote>
  <p><i>Effects:</i></p>
  <blockquote>
    <p>Appends <code>path::preferred_separator</code> to <code>pathname</code>, converting 
    format and encoding if required ([<a href="#path.arg.convert">path.arg.convert</a>]), unless:</p>
    <ul>
    <li>
    <p>an added separator 
    would be redundant, or</li>
    <li>
    <p>would change an relative path to an absolute path, or</li>
    <li>
    <p><code>p.empty()</code>, or</li>
    <li>
    <p><code>*p.native().cbegin()</code> is a separator.</li>
  </ul>
    <p>Appends the contents [<code>begin</code>,<code>end</code>) 
  or <code>source</code> to <code>pathname</code>, converting format and 
    encoding if required ([<a href="#path.arg.convert">path.arg.convert</a>]).</p>
  </blockquote>
  <p><i>Returns: </i><code>*this</code></p>
  </blockquote>
  
<h3><a name="path-concatenation"><code>path</code> concatenation</a> [path.concat]</h3>

<pre>path&amp; operator+=(const path&amp; x);
path&amp; operator+=(const string_type&amp; x);
path&amp; operator+=(const value_type* x);
path&amp; operator+=(value_type x);
template &lt;class Source&gt;
  path&amp; operator+=(Source const&amp; x);
template &lt;class CharT&gt;
  path&amp; operator+=(CharT x);
template &lt;class InputIterator&gt;
  path&amp; concat(InputIterator begin, InputIterator end);
template &lt;class InputIterator&gt;
  path&amp; concat(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt);</pre>

<blockquote><p><i>Postcondition:</i> <code>native() == prior_native + <i>effective-argument</i></code>,
 where <code>prior_native</code> is <code>native()</code> prior to the call to <code>operator+=</code>,
 and <code><i>effective-argument</i></code> is:</p>
 <ul><li>
   <p><code>x.native()</code> if <code>x</code> is present and is <code>const path&amp;</code>, otherwise</li>
 <li>
 <p><code>s</code>, where <code>s</code> is
  <code>std::basic_string&lt;typename std::iterator_traits&lt;InputIterator&gt;::value_type&gt;<br>s(begin, end)</code>,
   if <code>begin</code> and <code>end</code> arguments are present, otherwise</li>
 <li>
 <p><code>x</code>.</li></ul><p>If the value type of <code><i>effective-argument</i></code> would not be <code>path::value_type</code>, the actual argument or argument range is first
   converted so that <code><i>effective-argument</i></code> has value type <code>path::value_type</code>.</li> </p>
 <p><i>Returns: </i><code>*this</code></p>
 </blockquote>
<h3><a name="path-modifiers"> <code>
path</code> modifiers</a> [path.modifiers]</h3>

  <pre>void <a name="path-clear">clear</a>();</pre>

<blockquote>
<p><i>Postcondition:</i> <code>this-&gt;empty()</code> is true.</p>
</blockquote>

<pre>path&amp; <a name="path-make_preferred">make_preferred</a>();</pre>

<blockquote>
  <p><i>Effects:</i> <i>directory-separator</i>s are converted to <i>prefered-separator</i>s. 
  See [<a href="#Operating-system-examples">fs.os.examples</a>].</p>
  <p><i>Returns:</i> <code>*this</code></p>
</blockquote>



<pre>path&amp; <a name="path-remove_filename">remove_filename</a>();</pre>

<blockquote>
  <p><i>Returns: </i>As if, <code>*this = parent_path();</code></p>
  <p>[<i>Note:</i> This function is needed to efficiently implement <code>directory_iterator</code>. It is exposed to allow additional uses. The actual 
  implementation may be much more efficient than <code>*this = parent_path()</code>&nbsp; <i>—end 
  note</i>]</p>
</blockquote>

<pre>path&amp; <a name="path-replace_extension">replace_extension</a>(const path&amp; new_extension = path());</pre>

<blockquote>
  <p><i>Effects:</i></p>
  <ul>
    <li>
    <p>Any existing <code>extension()</code> is removed from the stored path, 
    then</li>
    <li>
    <p>iff
  <code>new_extension</code> is not empty and does not begin with a dot 
    character, a dot character is appended to the stored path, then</li>
    <li>
  <p>
  <code>new_extension</code> is appended to the stored path.</li>
  </ul>
  <p><i>Returns:</i> <code>*this</code></p>
</blockquote>

<pre><code>void <a name="path-swap">swap</a>(path&amp; rhs) noexcept;</code></pre>

<blockquote>
  <p><i>Effects:</i> Swaps the contents of the two paths.</p>
  <p><i>Complexity: </i>constant time.</p>
</blockquote>

  <h3><a name="path-lexical-operations"><code>path</code> lexical operations</a> 
  [path.lex.ops]</h3>
  <pre><span style="background-color: #E8FFE8">path </span><a name="lexically_normal"><span style="background-color: #E8FFE8">lexically_normal</span></a><span style="background-color: #E8FFE8">() const;</span></pre>
<blockquote>
<p><i>Overview:</i> Returns <code>*this</code> with redundant current directory 
(<i>dot</i>), parent directory (<i>dot-dot</i>), and <i>directory-separator</i> elements removed.</p>
<p><i>Returns:</i> <code>*this</code> in <a href="#normal-form">normal form</a>.</p>
<p><i>Remarks:</i> Uses <code>operator/=</code> to compose the returned path.</p>
<p>[<i>Example:</i></p>
<p><code>assert(path(&quot;foo/./bar/..&quot;).lexically_normal() == &quot;foo&quot;);<br>
assert(path(&quot;foo/.///bar/../&quot;).lexically_normal() == &quot;foo/.&quot;);</code></p>
<p>The above assertions will succeed.<i> </i>On Windows, the 
returned path&#39;s <i>directory-separator</i> characters will be backslashes rather than slashes, but that 
does not affect <code>path</code> equality.<i> —end example</i>]</p>
</blockquote>

<pre><span style="background-color: #E8FFE8">path </span><a name="lexically-relative"><span style="background-color: #E8FFE8">lexically_relative</span></a><span style="background-color: #E8FFE8">(const</span><span style="background-color: #E8FFE8"> path&amp; base) const;</span></pre>
  <blockquote>
  <p><i>Overview:</i> Returns <code>*this</code> made relative to <code>base</code>. 
  Treats empty or identical paths as corner cases, not errors. Does not resolve 
  symlinks. Does not first normalize <code>*this</code> or <code>base</code>.</p>

  <p><i>Remarks:</i> Uses <code>std::mismatch(begin(), end(), base.begin(), base.end())</code>, to determine the first mismatched element of
  <code>*this</code> and <code>base</code>. Uses <code>operator==</code> to 
  determine if elements match. </p>
  
  <p><i>Returns:</i> </p>
  
  <ul>
    <li>
  <code>path()</code> if the first mismatched element of <code>*this</code> is equal to <code>
  begin()</code> or the first mismatched element 
  of <code>base</code> is equal to <code>base.begin()</code>, or<br>&nbsp;
    </li>
    <li>
  <code>path(&quot;.&quot;)</code> if the first mismatched element of <code>
  *this</code> is equal to <code>
  end()</code> and the first mismatched element 
  of <code>base</code> is equal to <code>base.end()</code>, or<br>&nbsp;
    </li>
    <li>An object of class <code>path</code> composed via application of <code>
    operator/= path(&quot;..&quot;)</code> for each element in the half-open 
    range [first 
    mismatched element of <code>base</code>, <code>base.end()</code>), and then 
    application of <code>operator/=</code> for each element in the half-open 
    range 
    [first mismatched element of <code>*this</code>, <code>end()</code>).
    </li>
</ul>
  
<p>[<i>Example:</i></p>
<p><code>assert(path(&quot;/a/d&quot;).lexically_relative(&quot;/a/b/c&quot;) ==  &quot;../../d&quot;);<br>
assert(path(&quot;/a/b/c&quot;).lexically_relative(&quot;/a/d&quot;) ==  &quot;../b/c&quot;);<br>
assert(path(&quot;a/b/c&quot;).lexically_relative(&quot;a&quot;) == &quot;b/c&quot;);<br>
assert(path(&quot;a/b/c&quot;).lexically_relative(&quot;a/b/c/x/y&quot;) ==  &quot;../..&quot;);<br>
assert(path(&quot;a/b/c&quot;).lexically_relative(&quot;a/b/c&quot;) ==  &quot;.&quot;);<br>
assert(path(&quot;a/b&quot;).lexically_relative(&quot;c/d&quot;) ==  &quot;&quot;);</code></p>
<p>The above assertions will succeed.<i> </i>On Windows, the 
returned path&#39;s <i>directory-separator</i>s will be backslashes rather than 
forward slashes, but that 
does not affect <code>path</code> equality.<i> —end example</i>]</p>
  
  <p>[<i>Note:</i> If symlink following semantics are desired, use the  operational function <code>
  <a href="#op-proximate">relative</a></code>&nbsp; <i>—end note</i>]</p>
  
  <p>[<i>Note:</i> If <a href="#lexically_normal">normalization</a> is needed to ensure 
  consistent matching of elements, apply <code><a href="#lexically_normal">lexically_normal()</a></code> 
  to <code>*this</code>, <code>base</code>, or both. <i>—end note</i>]</p>

<h3> <a name="path-native-format-observers"><code><font size="4">path</font></code> native format observers</a> 
[path.native.obs]</h3>
<p>The string returned by all native format observers is in the <a href="#native-pathname-format">native pathname format</a>.</p>

<pre>const string_type&amp;  <a name="native">native</a>() const noexcept;</pre>

<blockquote>
<p><i>Returns:</i> <code>pathname</code>.</p>
</blockquote>

<pre>const value_type* <a name="c_str">c_str</a>() const noexcept;</pre>

<blockquote>
<p><i>Returns:</i> <code>pathname.c_str()</code>.</p>
</blockquote>

<pre><span style="background-color: #CCFFCC">string_type::size_type </span><a name="path-size"><span style="background-color: #CCFFCC">size</span></a><span style="background-color: #CCFFCC">() const noexcept;</span></pre>

<blockquote>
<p><i>Returns:</i> <code>pathname.size()</code>.</p>
</blockquote>

<pre>template &lt;class String&gt;
String <a name="string-template">string</a>(const codecvt_type&amp; cvt=codecvt()) const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>pathname</code>.</p>
<p><i>Remarks:</i> If <code>string_type</code> is a different type than <code>String</code>, conversion is performed by <code>cvt</code>.</p>
</blockquote>

<pre>string <a name="string">string</a>(const codecvt_type&amp; cvt=codecvt()) const;
wstring <a name="wstring">wstring</a>(const codecvt_type&amp; cvt=codecvt()) const;
u16string <a name="u16string">u16string</a>() const;
u32wstring <a name="u32wstring">u32wstring</a>() const; </pre>

<blockquote>
<p><i>Returns:</i> <code>pathname</code>.</p>
<p><i>Remarks:</i> If <code>string_type</code> is a different type than 
function's return type, conversion is performed by <code>cvt</code>.</p>
</blockquote>

<h3> <a name="path-generic-format-observers"><code><font size="4">path</font></code> generic format observers</a> 
[path.generic.obs]</h3>
<p>The string returned by all generic format observers is in the <a href="#generic-pathname-format">generic pathname format</a>.</p>

<pre>template &lt;class String&gt;
String <a name="generic_string-template">generic_string</a>(const codecvt_type&amp; cvt=codecvt()) const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>pathname</code>.</p>
<p><i>Remarks:</i> If <code>string_type</code> is a different type than <code>String</code>, conversion is performed by <code>cvt</code>.</p>
</blockquote>

<pre>string <a name="generic_string">generic_string</a>(const codecvt_type&amp; cvt=codecvt()) const;
wstring <a name="generic_wstring">generic_wstring</a>(const codecvt_type&amp; cvt=codecvt()) const;
u16string <a name="generic_u16string">generic_u16string</a>() const;
u32wstring <a name="generic_u32wstring">generic_u32wstring</a>() const; </pre>

<blockquote>
<p><i>Returns:</i> <code>pathname</code>.</p>
<p><i>Remarks:</i>&nbsp; If <code>string_type</code> is a different type than 
function's return type, conversion is performed by <code>cvt</code>.</p>
</blockquote>

<h3> <a name="path-compare"><code>path</code> compare</a> [path.compare]</h3>

<pre>int compare(const path&amp; p) const noexcept;</pre>

<blockquote>
  <p><i>Returns:</i> A value less than 0 if the elements of <code>*this</code> are lexicographically less than the elements of <code>p</code>, otherwise a 
  value greater than 0 if the elements of <code>*this</code> are 
  lexicographically greater than the elements of <code>p</code>, otherwise 0.</p>
  <p>Remark: The elements are determined as if by iteration over the half-open 
  range [<code>begin()</code>, <code>end()</code>) for <code>*this</code> and&nbsp; <code>p</code>.</p>
</blockquote>

<pre>int compare(const std::string&amp; s) const</pre>

<blockquote>
  <p><i>Returns:</i> <code>compare(path(s))</code>.</p>
</blockquote>

<pre>int compare(const value_type* s) const</pre>

<blockquote>
  <p><i>Returns:</i> <code>compare(path(s))</code>.</p>
</blockquote>
<h3> <a name="path-decomposition"> <code><font size="4">path</font></code> decomposition</a> 
[path.decompose]</h3>
<p><span style="background-color: #E0E0E0"><i>See the <a href="#path-decomposition-table">Path decomposition table</a> for examples 
for values returned by decomposition functions. The <a href="tutorial.html#Using-path-decomposition">Tutorial</a> may also be 
helpful.</i></span></p>

<pre>path <a name="path-root_name">root_name</a>() const;</pre>

<blockquote>
<p><i>Returns:</i> <i>root-name,</i> if <code>pathname</code> includes <i>root-name</i>, otherwise <code>path()</code>. </p>
</blockquote>

<pre>path <a name="path-root_directory">root_directory</a>() const;</pre>

<blockquote>
<p><i>Returns:</i> <i>root-directory</i>, if <code>pathname</code> includes <i>root-directory</i>, otherwise <code>path()</code>.</p>
<p>If <i>root-directory</i> is composed of <i>slash name</i>, <i>slash</i> is 
excluded from the returned string.</p>
</blockquote>

<pre>path <a name="path-root_path">root_path</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>root_name() / root_directory()</code></p>
</blockquote>

<pre>path <a name="path-relative_path">relative_path</a>() const;</pre>

<blockquote>
<p><i>Returns:</i> A <code>path</code> composed from <code>pathname</code>, if <code>!empty()</code>, beginning 
with the first <i>filename</i> after <i>root-path</i>. Otherwise, <code>path()</code>.</p>
</blockquote>

<pre>path <a name="path-parent_path">parent_path</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>(empty() || begin() == —end()) ? path() : <i>pp</i></code>, where <code><i>pp</i></code> is constructed as if by 
  starting with an empty <code>path</code> and successively applying <code>operator/=</code> for each element in the range <code>begin()</code>, <code>—end()</code>.</p>
  <p>[<i>Example:</i></p>
  <blockquote>
    
    <pre>std::cout &lt;&lt; path(&quot;/foo/bar.txt&quot;).parent_path(); // outputs &quot;/foo&quot;
std::cout &lt;&lt; path(&quot;/foo/bar&quot;).parent_path();     // outputs &quot;/foo&quot;
std::cout &lt;&lt; path(&quot;/foo/bar/&quot;).parent_path();    // outputs &quot;/foo/bar&quot;
std::cout &lt;&lt; path(&quot;/&quot;).parent_path();            // outputs &quot;&quot;
std::cout &lt;&lt; path(&quot;.&quot;).parent_path();            // outputs &quot;&quot;
std::cout &lt;&lt; path(&quot;..&quot;).parent_path();           // outputs &quot;&quot;</pre>
    
  </blockquote>
  <p> See the last bullet item in the <a href="#path-iterators">
  forward traversal order</a> list for why the <code>&quot;/foo/bar/&quot;</code> example 
  doesn&#39;t output <code>&quot;/foo&quot;</code>.</p>
  <p> <i>—end example</i>]</p>
</blockquote>

<pre>path <a name="path-filename">filename</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>empty() ? path() : *—end()</code></p>
  <p>[<i>Example:</i></p>
  <blockquote>
    
    <pre>std::cout &lt;&lt; path(&quot;/foo/bar.txt&quot;).filename(); // outputs &quot;bar.txt&quot;
std::cout &lt;&lt; path(&quot;/foo/bar&quot;).filename();     // outputs &quot;bar&quot;
std::cout &lt;&lt; path(&quot;/foo/bar/&quot;).filename();    // outputs &quot;.&quot;
std::cout &lt;&lt; path(&quot;/&quot;).filename();            // outputs &quot;/&quot;
std::cout &lt;&lt; path(&quot;.&quot;).filename();            // outputs &quot;.&quot;
std::cout &lt;&lt; path(&quot;..&quot;).filename();           // outputs &quot;..&quot;</pre>
    
  </blockquote>
  <p> See the last bullet item in the <a href="#path-iterators">
  forward traversal order</a> list for why the <code>&quot;/foo/bar/&quot;</code> example 
  doesn&#39;t output <code>&quot;bar&quot;</code>.</p>
  <p> <i>—end example</i>]</p>
</blockquote>

<pre>path <a name="path-stem">stem</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> if <code>p.filename()</code> contains a dot but does not 
  consist solely of one or to two dots, returns 
  the substring of <code>p.filename()</code> starting at its beginning and 
  ending at the last dot (the dot is not included). Otherwise, 
  returns <code>p.filename()</code>.</p>
  <p>[<i>Example:</i></p>
  <blockquote>
    
    <pre><code>std::cout &lt;&lt; path(&quot;/foo/bar.txt&quot;).stem();</code> // outputs &quot;<code>bar</code>&quot;
path p = &quot;foo.bar.baz.tar&quot;;
for (; !p.extension().empty(); p = p.stem())
  std::cout &lt;&lt; p.extension() &lt;&lt; '\n';
  // outputs: .tar
  //          .baz
  //          .bar</pre>
    
  </blockquote>
  <p> <i>—end example</i>]</p>
</blockquote>

<pre>path <a name="path-extension">extension</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> if <code>p.filename()</code> contains a dot but does not 
  consist solely of one or to two dots, returns 
  the substring of <code>p.filename()</code> starting at the rightmost dot 
  and ending at the path's end. Otherwise, returns an empty <code>path</code> object. </p>
  <p><i>Remarks:</i> Implementations are permitted but not required to define additional 
  behavior for file systems which append additional elements to extensions, such 
  as alternate data streams or partitioned dataset names.</p>
  <p>[<i>Example:</i></p>
  <blockquote>
    
    <pre><code>std::cout &lt;&lt; path(&quot;/foo/bar.txt&quot;).extension(); //</code> outputs &quot;<code>.txt</code>&quot;</pre>
    
  </blockquote>
  <p> <i>—end example</i>]</p>
  <p>[<i>Note:<b> </b></i>The dot is included in the return value so that it is 
  possible to distinguish between no extension and an empty extension.
  See <a href="http://permalink.gmane.org/gmane.comp.lib.boost.devel/199744">
  http://permalink.gmane.org/gmane.comp.lib.boost.devel/199744</a> for more 
  extensive rationale.&nbsp; <i>—end note</i>]</p>
</blockquote>
<h3> <a name="path-query"> <code><font size="4">path</font></code> query</a> [path.query]</h3>

<pre>bool <a name="path-empty">empty</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>m_pathname.empty()</code>.</p>
</blockquote>

<pre><span style="background-color: #CCFFCC">bool </span><a name="filename_is_dot"><span style="background-color: #CCFFCC">filename_is_dot</span></a><span style="background-color: #CCFFCC">() const;</span></pre>

<blockquote>
  <p><i>Returns:</i> <code>filename() == path(&quot;.&quot;)</code></p>
  <p>[<i>Example:</i></p>
  <blockquote>
    
    <pre>std::cout &lt;&lt; path(&quot;.&quot;).filename_is_dot();     // outputs 1
std::cout &lt;&lt; path(&quot;/.&quot;).filename_is_dot();    // outputs 1
std::cout &lt;&lt; path(&quot;foo/.&quot;).filename_is_dot(); // outputs 1
std::cout &lt;&lt; path(&quot;foo/&quot;).filename_is_dot();  // outputs 1
std::cout &lt;&lt; path(&quot;/&quot;).filename_is_dot();     // outputs 0
std::cout &lt;&lt; path(&quot;/foo&quot;).filename_is_dot();  // outputs 0
std::cout &lt;&lt; path(&quot;/foo.&quot;).filename_is_dot(); // outputs 0
std::cout &lt;&lt; path(&quot;..&quot;).filename_is_dot();    // outputs 0</pre>
    
  </blockquote>
  <p> See the last bullet item in the <a href="#path-iterators">forward traversal order</a> 
  list for why <code>path(&quot;foo/&quot;).filename()</code> is a dot filename.</p>
  <p> <i>—end example</i>]</p>
</blockquote>

<pre><span style="background-color: #CCFFCC">bool </span><span style="background-color: #CCFFCC"><a name="filename_is_dot­_dot">filename_is_dot_dot</a>() const;</span></pre>

<blockquote>
  <p><i>Returns:</i> <code>filename() == path(&quot;..&quot;)</code></p>
</blockquote>

<pre>bool <a name="path-has_root_path">has_root_path</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-root_path">root_path</a>().empty()</code></p>
</blockquote>

<pre>bool <a name="path-has_root_name">has_root_name</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-root_name">root_name</a>().empty()</code></p>
</blockquote>

<pre>bool <a name="path-has_root_directory">has_root_directory</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-root_directory">root_directory</a>().empty()</code></p>
</blockquote>

<pre>bool <a name="path-has_relative_path">has_relative_path</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-has_relative_path">relative_path</a>().empty()</code></p>
</blockquote>

<pre>bool <a name="path-has_parent_path">has_parent_path</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-parent_path">parent_path</a>().empty()</code></p>
</blockquote>

<pre>bool <a name="path-has_filename">has_filename</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-filename">filename</a>().empty()</code></p>
</blockquote>

<pre>bool <a name="path-has_stem">has_stem</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-stem">stem</a>().empty()</code></p>
</blockquote>

<pre>bool <a name="path-has_extension">has_extension</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-has_extension">extension</a>().empty()</code></p>
</blockquote>

<pre>bool <a name="path-is_absolute">is_absolute</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>true</code> if the elements of <code>root_path()</code> uniquely identify a directory, else <code>false</code>.</p>
</blockquote>

<pre>bool <a name="path-is_relative">is_relative</a>() const;</pre>

<blockquote>
  <p><i>Returns:</i> <code>!is_absolute()</code>.</p>
</blockquote>
<h3> <a name="path-iterators"> <code>
<font size="4">path</font></code> iterators</a> [path.itr]</h3>
<p> Path iterators <code>iterator</code>, <code>const_iterator</code>,
<code>reverse_iterator</code>, and <code>const_reverse_iterator</code> iterate over the elements of the stored pathname.</p>
<p> Path iterators are constant iterators satisfying  
the requirements of a bidirectional iterator (C++ Std, 24.1.4 Bidirectional 
iterators [lib.bidirectional.iterators]). The <code>value_type</code>&nbsp; of 
an iterator is <code>path</code>.</p>
  <blockquote>
<p> [<i>Note:</i> Path iterators store their value objects internally 
and when dereferenced return references to those internal objects. They cannot 
be used with iterator adaptors such as <code>std::reverse_iterator</code> that 
assume references obtained by dereferencing an iterator point to objects that 
out-live the iterator itself. <i>—end note</i>] </p>
</blockquote>
  <p>Calling any non-const member function of a <code>path</code> object 
  invalidates all iterators referring to elements of that object.</p>
<p> The forward traversal order is as follows:</p>
<ul>
  <li>The <i>root-name</i> element, if present.</li>
  <li>The <i>root-directory</i> element, if present, in the generic format. <i>
  [note:</i> the generic format is required to ensure lexicographical 
  comparison works correctly. <i>—end note</i>]</li>
  <li>Each successive <i>filename</i> element, if present.</li>
  <li><i>Dot</i>, if one or more trailing non-root <i>slash</i> 
  characters are present.|</li>
</ul>
  <blockquote>
  <p>[<i>Note:</i> Treating the last element during iteration as <i>dot</i> when 
  there is a trailing directory separator enables lexical (i.e. syntactic) 
  distinction between paths to directories versus paths to regular files. Such a 
  distinction is usually irrelevant on POSIX and Windows based operating 
  systems, but may be a requirement on other operating systems. <i>—end note</i>]</p>
  </blockquote>
  <p>The backward traversal order is the reverse of forward traversal.</p>
  <pre>iterator begin() const;</pre>
<blockquote>
  <p><i>Returns:</i> An iterator for the first  element in forward traversal 
  order. If no elements are present, the end iterator.</p>
</blockquote>
<pre>iterator end() const;</pre>
<blockquote>
  <p><i>Returns:</i> The end iterator.</p>
</blockquote>
  <pre>reverse_iterator rbegin() const;</pre>
<blockquote>
  <p><i>Returns:</i> An iterator for the first element in backward traversal 
  order. If no elements are present, the end iterator.</p>
</blockquote>
<pre>reverse_iterator rend() const;</pre>
<blockquote>
  <p><i>Returns:</i> The end iterator.</p>
</blockquote>
 <h3><a name="path-imbued-locale"><code><font size="4"> path</font></code> 
 imbued locale</a> [path.imbued.locale]</h3>
 <p><code>path</code> operations sometimes require encoding conversions between
 <code>pathname</code> and some other string object where one of the value types 
 is <code>char</code> and the other is <code>wchar_t</code>. Such conversions 
 shall be performed by the <code>path::codecvt()</code> facet.</p>
 <blockquote>
 <p><span style="background-color: #FFFF00">[</span><i><span style="background-color: #FFFF00">Example:</span></i><span style="background-color: #FFFF00"> 
 ... </span><i><span style="background-color: #FFFF00">—end example</span></i><span style="background-color: #FFFF00">]</span></p>
 </blockquote>
 <pre>static std::locale <a name="path-imbue">imbue</a>(const std::locale&amp; loc);</pre>
<blockquote>
  <p><i>Effects:</i> Stores a copy of <code>loc</code> as the imbued <code>path</code> 
  locale.</p>
  <p><i>Returns:</i> The previous imbued <code>path</code> locale.</p>
  <p><i>Remarks:</i> The initial value of the imbued <code>path</code> locale is 
  operating system dependent. It shall be a locale with a <code>codecvt</code> 
  facet for a <code>char</code> string encoding appropriate for the operating 
  system. See ([<a href="#Operating-system-examples">fs.os.examples</a>]).&nbsp; </p>
</blockquote>
<pre>static const codecvt_type&amp; <a name="path-codecvt">codecvt</a>();</pre>
<blockquote>
  <p><i>Returns:</i> The <code>codecvt</code> facet for the imbued<code> path</code> 
  locale .</p>
</blockquote>


<h3> <a name="path-deprecated-functions"><code><font size="4"> path</font></code> deprecated functions</a></h3>
<p> Several member functions from previous versions of <code>class path</code> have been deprecated, either because they have been renamed or because the 
functionality is no longer desirable or has become obsolete.</p>
<p> Deprecated functions available by default; will be suppressed if <code>BOOST_FILESYSTEM_NO_DEPRECATED</code> is defined:</p>
<blockquote>
  <pre>path&amp;  remove_leaf()           { return remove_filename(); }
path   leaf() const            { return filename(); }
path   branch_path() const     { return parent_path(); }
bool   has_leaf() const        { return !m_path.empty(); }
bool   has_branch_path() const { return !parent_path().empty(); }</pre>
</blockquote>
<p> Deprecated functions not available by default; will be supplied if <code>BOOST_FILESYSTEM_DEPRECATED</code> is defined:</p>
<blockquote>
<pre>const std::string  file_string() const               { return native_string(); }
const std::string  directory_string() const          { return native_string(); }
const std::string  native_file_string() const        { return native_string(); }
const std::string  native_directory_string() const   { return native_string(); }
const string_type  external_file_string() const      { return native(); }
const string_type  external_directory_string() const { return native(); }</pre>
</blockquote>

<h3> <a name="path-non-member-functions"> <code><font size="4">path</font></code> non-member functions</a> 
[path.non-member]</h3>

  <pre>bool lexicographical_compare(path::iterator first1, path::iterator last1,
                             path::iterator first2, path::iterator last2);</pre>
<blockquote>
  <p><i>Returns:</i> <code>true</code> if the sequence of <code>native()</code> strings for the elements defined by the half-open range <code>[first1,last1)</code> is 
  lexicographically less than the sequence of <code>native()</code> strings for 
  the elements defined by the half-open range <code>[first2,last2)</code>. Returns <code>false</code> otherwise.</p>
  <p><i>Remarks:</i> If two sequences have the same number of elements and their 
  corresponding elements are equivalent, then neither sequence is 
  lexicographically less than the other. If one sequence is a prefix of the 
  other, then the shorter sequence is lexicographically less than the longer 
  sequence. Otherwise, the lexicographical comparison of the sequences yields 
  the same result as the comparison of the first corresponding pair of elements 
  that are not equivalent.</p>
  <p>[<i>Note:</i> A <code>path</code> aware <code>lexicographical_compare</code> algorithm is provided for historical reasons. <i>—end note</i>]</p>
</blockquote>

  <div>

  <pre><span style="background-color: #CCFFCC">path lexically_</span><a name="lex-normal"><span style="background-color: #CCFFCC">normal</span></a><span style="background-color: #CCFFCC">(const path&amp; p);</span></pre>

  </div>

<blockquote>
  <p><i>Overview:</i> Returns <code>p</code> with redundant current 
  directory (<i>dot</i>), parent directory (<i>dot-dot</i>), and <i>
  directory-separator</i> elements removed.</p>
  <p><i>Returns:</i> <code>p</code> in
  <a href="#normal-form">
  normal form</a>.</p>
  <p><i>Remarks:</i> Uses <code>operator/=</code> to compose the 
  returned path.</p>
  <p>[<i>Example:</i></p>
  <p><code>assert(lexically_normal(&quot;foo/./bar/..&quot;) == &quot;foo&quot;);<br>
  assert(lexically_normal(&quot;foo/.///bar/../&quot;) == &quot;foo/.&quot;);</code></p>
  <p>All of the above assertions will succeed.<i> </i>On Windows, the 
  returned path&#39;s <i>directory-separator</i> characters will be backslashes 
  rather than slashes, but that does not affect <code>path</code> equality.<i> 
  —end example</i>]</p>
</blockquote>

  <div>

  <pre>path lexically_<a name="lex-relative">relative</a>(const path&amp; p, const path&amp; base);</pre>

  </div>

<blockquote>
  <p><i>Overview:</i> Returns <code>p</code> made relative to <code>
  base</code>. Treats empty or identical paths as corner cases, not errors. Does 
  not resolve symlinks. Does not first normalize <code>p</code> or <code>base</code>.</p>
  <p><i>Remarks:</i> Uses <code>std::mismatch(p.begin(), p.end(), 
  base.begin(), base.end())</code>, to determine the first mismatched element of
  <code>p</code> and <code>base</code>. Uses <code>operator==</code> to 
  determine if elements match. </p>
  <p><i>Returns:</i> </p>
  <ul>
    <li>
    <p><code>path()</code> if the first mismatched element of <code>p</code> 
    is equal to <code>p.begin()</code> or the first mismatched element of <code>
    base</code> is equal to <code>base.begin()</code>, or<br>
    &nbsp; </li>
    <li>
    <p><code>path(&quot;.&quot;)</code> if the first mismatched element of <code>
    p</code> is equal to <code>p.end()</code> and the first mismatched element 
    of <code>base</code> is equal to <code>base.end()</code>, or<br>
    &nbsp; </li>
    <li>
    <p>An object of class <code>path</code> composed via application 
    of <code>operator/= path(&quot;..&quot;)</code> for each element in the half-open 
    range [first mismatched element of <code>base</code>, <code>base.end()</code>), 
    and then application of <code>operator/=</code> for each element in the 
    half-open range [first mismatched element of <code>p</code>, <code>p.end()</code>).
    </li>
  </ul>
  <p>[<i>Example:</i></p>
  <p><code>assert(lexically_relative(&quot;/a/d&quot;, &quot;/a/b/c&quot;) == &quot;../../d&quot;);<br>
  assert(lexically_relative(&quot;/a/b/c&quot;, &quot;/a/d&quot;) == &quot;../b/c&quot;);<br>
  assert(lexically_relative(&quot;a/b/c&quot;, &quot;a&quot;) == &quot;b/c&quot;);<br>
  assert(lexically_relative(&quot;a/b/c&quot;, &quot;a/b/c/x/y&quot;) == &quot;../..&quot;);<br>
  assert(lexically_relative(&quot;a/b/c&quot;, &quot;a/b/c&quot;) == &quot;.&quot;);<br>
  assert(lexically_relative(&quot;a/b&quot;, &quot;c/d&quot;) == &quot;&quot;);</code></p>
  <p>All of the above assertions will succeed.<i> </i>On Windows, the 
  returned path&#39;s <i>directory-separator</i>s will be backslashes rather than 
  forward slashes, but that does not affect <code>path</code> equality.<i> —end 
  example</i>]</p>
  <p>[<i>Note:</i> If symlink following semantics are desired, use the 
  operational function <code>
  <a href="#op-relative">
  relative</a></code>&nbsp; <i>—end note</i>]</p>
  <p>[<i>Note:</i> If <a href="#normal-form">normalization</a> is needed to ensure consistent matching of elements, wrap
  <code>p</code>, <code>base</code>, or both in calls <code>
  <a href="#lex-normal">
  lexically_normal()</a></code>. <i>—end note</i>]</p>
</blockquote>
<pre>void swap( path&amp; lhs, path&amp; rhs )</pre>
<blockquote>
  <p><i>Effects: </i><code>lhs.swap(rhs)</code>.</p>
</blockquote>
<pre>std::size_t <a name="hash_value">hash_value</a> (const path&amp; p);</pre>
<blockquote>
  <p><i>Returns:</i> A hash value for the path <code>p</code>. If
  for two paths, <code>p1 == p2</code> then <code>hash_value(p1) == hash_value(p2)</code>.</p>
  <p>This allows paths to be used with <a href="../../functional/hash/index.html">Boost.Hash</a>.</p>
</blockquote>
<pre>bool operator&lt; (const path&amp; lhs, const path&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>return lhs.compare(rhs.begin) &lt; 0</code>.</p>
</blockquote>
<pre>bool operator&lt;=(const path&amp; lhs, const path&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>!(rhs &lt; lhs)</code>.</p>
</blockquote>
<pre>bool operator&gt; (const path&amp; lhs, const path&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>rhs &lt; lhs</code>.</p>
</blockquote>
<pre>bool operator&gt;=(const path&amp; lhs, const path&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>!(lhs &lt; rhs)</code>.</p>
</blockquote>
<pre>bool operator==(const path&amp; lhs, const path&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>!(lhs &lt; rhs) &amp;&amp; !(rhs &lt; lhs)</code>.</p>
  <p>[<i>Note:</i> <a name="Path-equality">Path equality</a> and path 
  equivalence have different semantics.</p>
  <p>Equality is determined by the <code>path</code> non-member <code>operator==</code>, which considers the two path's lexical 
  representations only. Thus <code>path(&quot;foo&quot;) == &quot;bar&quot;</code> is never <code>true</code>.</p>
  <p>Equivalence is determined by the <a href="#equivalent"><code>equivalent()</code></a> non-member function, which determines if two paths <a href="#path">resolve</a> to the same file system entity. 
  Thus <code>equivalent(&quot;foo&quot;, &quot;bar&quot;)</code> will be <code>true</code> when both paths resolve to the same file.</p>
  <p>Programmers wishing to determine if two paths are &quot;the same&quot; must decide if 
  &quot;the same&quot; means &quot;the same representation&quot; or &quot;resolve to the same actual 
  file&quot;, and choose the appropriate function accordingly. <i>—end note</i>]</p>
</blockquote>
<pre>bool operator!=(const path&amp; lhs, const path&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>!(lhs == rhs)</code>.</p>
</blockquote>
<pre>path operator/ (const path&amp; lhs, const path&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>path(lhs) /= rhs</code>.</p>
</blockquote>
<h3> <a name="path-non-member-operators"><code><font size="4">path</font></code></a><a name="path-inserter-extractor"> inserter 
  and extractor</a> [path.io]</h3>
<p> The inserter and extractor delimit the string with double-quotes (<code>&quot;</code>) 
so that paths with embedded spaces will round trip correctly. Ampersand (<code>&amp;</code>) 
is as an escape character, so the path can itself contain double quotes.</p>
<pre>template &lt;class Char, class Traits&gt;
std::basic_ostream&lt;Char, Traits&gt;&amp; operator&lt;&lt;(std::basic_ostream&lt;Char, Traits&gt;&amp; os,
                                             const path&amp; p)
</pre>
<blockquote>
  <p><i>Effects: </i>Insert characters into <code>os</code>:</p>
  <ul>
    <li>
  <p>A double-quote.</p>
    </li>
    <li>
  <p>Each character in <code>p.string&lt;std::basic_string&lt;Char&gt;&gt;()</code>. 
  If the character to be inserted is equal to the escape character or a 
  double-quote, as determined by <code>operator==</code>, first insert the 
  escape character.</p>
    </li>
    <li>
  <p>A double-quote.</p>
    </li>
  </ul>
  <p><i>Returns:</i> <code>os</code></p>
</blockquote>
<pre>template &lt;class Char, class Traits&gt;
inline std::basic_istream&lt;Char, Traits&gt;&amp; operator&gt;&gt;(std::basic_istream&lt;Char, Traits&gt;&amp; is,
                                                    path&amp; p)
</pre>
<blockquote>
  <p><i>Effects:&nbsp; </i><code>&nbsp;std::basic_string&lt;Char&gt; str;<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; is &gt;&gt; <a href="../../io/doc/quoted_manip.html">boost::io::quoted</a>(str, static_cast&lt;Char&gt;('&amp;'));<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; p = str;</code></p>
  <p><i>Effects:&nbsp; </i>Extract characters from os:</p>
  <ul>
    <li>If the first character that would be extracted is equal to double-quote, 
    as determined by <code>operator==</code>, then:<ul>
      <li>Discard the initial double-quote.</li>
      <li>Save the value and then turn off the <code>skipws</code> flag.</li>
      <li><code>p.clear()</code></li>
      <li>Until an unescaped double-quote character is reached or <code>
      is.not_good()</code>, extract characters from <code>os</code> and append 
      them to <code>p</code>, except that if an escape character is reached, 
      ignore it and append the next character to <code>p</code>.</li>
      <li>Discard the final double-quote character.</li>
      <li>Restore the <code>skipws</code> flag to its original value.</li>
    </ul>
    </li>
    <li>Otherwise, <code>os &gt;&gt; p</code>.</li>
  </ul>
  <p><i>Returns:</i> <code>is</code></p>
  </blockquote>
<h2><a name="Class-filesystem_error">Class <code>filesystem_error</code> 
[class.filesystem_error]</a></h2>
<pre>namespace boost
{
  namespace filesystem
  {
      class filesystem_error : public system_error
      {
      public:
        filesystem_error();
        filesystem_error(const filesystem_error&amp;);
        <a href="#filesystem_error-2-arg">filesystem_error</a>(const std::string&amp; what_arg,
          system::error_code ec);
        <a href="#filesystem_error-3-arg">filesystem_error</a>(const std::string&amp; what_arg,
          const path&amp; p1, system::error_code ec);
        <a href="#filesystem_error-4-arg">filesystem_error</a>(const std::string&amp; what_arg,
          const path&amp; p1, const path&amp; p2, system::error_code ec);

        filesystem_error&amp; filesystem_error(const filesystem_error&amp;);
       ~filesystem_error();

        filesystem_error&amp; operator=(const filesystem_error&amp;);

        const path&amp; <a href="#filesystem_error-path1">path1</a>() const;
        const path&amp; <a href="#filesystem_error-path2">path2</a>() const;

        const char * <a href="#filesystem_error-what">what</a>() const;
      };
  }  // namespace filesystem
}  // namespace boost</pre>
<p>The class template <code>filesystem_error</code> defines the type of 
objects thrown as exceptions to report file system errors from functions described in this 
reference documentation.</p>
<h3> <a name="filesystem_error-members"> <code>filesystem_error</code> members</a> 
[filesystem_error.members]</h3>
<pre><a name="filesystem_error-2-arg">filesystem_error</a>(const std::string&amp; what_arg, error_code ec);</pre>
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="46%">
    <tr>
      <td width="18%"><b>Expression</b></td>
      <td width="82%"><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%" bgcolor="#FFFFFF"><code>
      runtime_error::what()</code></td>
      <td width="82%" bgcolor="#FFFFFF">
      <code><i>what_arg</i>.c_str()</code></td>
    </tr>
    <tr>
      <td width="18%"><code>code()</code></td>
      <td width="82%"><code>ec</code></td>
    </tr>
    <tr>
      <td width="18%"><code>path1().empty()</code></td>
      <td width="82%"><code>true</code></td>
    </tr>
    <tr>
      <td width="18%"><code>path2().empty()</code></td>
      <td width="82%"><code>true</code></td>
    </tr>
  </table>
</blockquote>
<pre><a name="filesystem_error-3-arg">filesystem_error</a>(const std::string&amp; what_arg, const path&amp; p1, error_code ec);</pre>
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="46%">
    <tr>
      <td width="18%"><b>Expression</b></td>
      <td width="82%"><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%" valign="top"><code>
      runtime_error::what()</code></td>
      <td width="82%">
      <code><i>what_arg</i>.c_str()</code></td>
    </tr>
    <tr>
      <td width="18%" valign="top"><code>code()</code></td>
      <td width="82%"><code>ec</code></td>
    </tr>
    <tr>
      <td width="18%" valign="top"><code>path1()</code></td>
      <td width="82%">Reference to stored copy of <code>p1</code></td>
    </tr>
    <tr>
      <td width="18%" valign="top"><code>path2().empty()</code></td>
      <td width="82%"><code>true</code></td>
    </tr>
  </table>
</blockquote>
<pre><a name="filesystem_error-4-arg">filesystem_error</a>(const std::string&amp; what_arg, const path&amp; p1, const path&amp; p2, error_code ec);</pre>
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="46%">
    <tr>
      <td width="18%"><b>Expression</b></td>
      <td width="82%"><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%"><code>
      runtime_error::what()</code></td>
      <td width="82%">
      <u>
      <code><i>w</i></code></u><code><i>hat_arg</i>.c_str()</code></td>
    </tr>
    <tr>
      <td width="18%"><code>code()</code></td>
      <td width="82%"><code>ec</code></td>
    </tr>
    <tr>
      <td width="18%"><code>path1()</code></td>
      <td width="82%">Reference to stored copy of <code>p1</code></td>
    </tr>
    <tr>
      <td width="18%"><code>path2()</code></td>
      <td width="82%">Reference to stored copy of <code>p2</code></td>
    </tr>
  </table>
</blockquote>
<pre>const path&amp; <a name="filesystem_error-path1">path1</a>() const;</pre>
<blockquote>
  <p><i>Returns:</i> Reference to copy of <code>p1</code> stored by the 
  constructor, or, if none, an empty path.</p>
</blockquote>
<pre>const path&amp; <a name="filesystem_error-path2">path2</a>() const;</pre>
<blockquote>
  <p><i>Returns:</i> Reference to copy of <code>p2</code> stored by the 
  constructor, or, if none, an empty path.</p>
</blockquote>
<pre>const char* <a name="filesystem_error-what">what</a>() const;</pre>
<blockquote>
  <p><i>Returns: </i>A string containing <code>runtime_error::what()</code>. The exact format is unspecified. 
  Implementations are encouraged but not required to include <code>path1.native_string()</code>if not empty, <code>path2.native_string()</code>if 
  not empty, and <code>system_error::what()</code> strings in the returned 
  string.</p>
</blockquote>
<h2><a name="Enum-file_type">Enum file_type</a> [enum.file_type]</h2>
<p>This enum specifies constants uses to identify file types.</p>
<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111">
  <tr>
    <td><b>Constant Name</b></td>
    <td><b>Meaning</b></td>
  </tr>
  <tr>
    <td><code>status_error</code></td>
    <td>An error occurred while trying to obtain the status of the file. The 
    file simply not being found is <b><u>not</u></b> considered a status error. </td>
  </tr>
  <tr>
    <td><code>file_not_found</code></td>
    <td>The file could not be found</td>
  </tr>
  <tr>
    <td><code>regular_file</code></td>
    <td>Regular file</td>
  </tr>
  <tr>
    <td><code>directory_file</code></td>
    <td>Directory file</td>
  </tr>
  <tr>
    <td><code>symlink_file</code></td>
    <td>Symbolic link file</td>
  </tr>
  <tr>
    <td><code>block_file</code></td>
    <td>Block special file</td>
  </tr>
  <tr>
    <td><code>character_file</code></td>
    <td>Character special file</td>
  </tr>
  <tr>
    <td><code>fifo_file</code></td>
    <td>FIFO or pipe file</td>
  </tr>
  <tr>
    <td><code>socket_file</code></td>
    <td>Socket file</td>
  </tr>
  <tr>
    <td><code>type_unknown</code></td>
    <td>The file exists, but it is of a system specific type not covered by any 
    of the above cases.</td>
  </tr>
</table>
<h2><a name="Enum-perms">Enum perms</a> [enum.perms]</h2>
<p>This <code>enum</code> specifies bitmask constants uses to identify file 
permissions. <i><span style="background-color: #E0E0E0">ISO/</span><span style="background-color: #E0E0E0">IEC</span><span style="background-color: #E0E0E0"> 9945 
(POSIX) specifies actual values, and those values have been adopted here because 
they are very familiar and ingrained for many POSIX 
users.</span></i></p>
<blockquote>
<p><span style="background-color: #FFFF00">Windows: All permissions except write are currently ignored. There is only a 
single write permission; setting write permission for owner, group, or others 
sets write permission for all, and removing write permission for owner, group, 
or others removes write permission for all. </span> </p>
</blockquote>
<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111">
  <tr>
    <td><b>Name</b></td>
    <td align="center"><b>Value<br>
    (octal)</b></td>
    <td align="center"><b>ISO/IEC 9945<br>
    macro</b></td>
    <td><b>Definition or notes</b></td>
  </tr>

<tr><td>
  <p><code>no_perms</code></td><td><code>0</code></td><td></td>
  <td>There are no permissions set for the file. Note: <code>file_not_found</code> is <code>no_perms</code> rather than <code>perms_not_known</code></td>
</tr>
<tr><td><code>owner_read</code></td><td><code>0400</code></td><td> <code>S_IRUSR</code></td>
  <td> Read permission, owner</td>
</tr>
<tr><td><code>owner_write</code></td><td><code>0200</code></td><td> <code>S_IWUSR</code></td>
  <td> Write permission, owner</td>
</tr>
<tr><td><code>owner_exe</code></td><td><code>0100</code></td><td>  <code>S_IXUSR</code></td>
  <td> Execute/search permission, owner</td>
</tr>
<tr><td><code>owner_all</code></td><td><code>0700</code></td><td>  <code>S_IRWXU</code></td>
  <td> Read, write, execute/search by owner; <code>owner_read | owner_write | owner_exe</code></td>
</tr>
<tr><td><code>group_read</code></td><td><code>040</code></td><td>  <code>S_IRGRP</code></td>
  <td> Read permission, group</td>
</tr>
<tr><td><code>group_write</code></td><td><code>020</code></td><td> <code>S_IWGRP</code></td>
  <td> Write permission, group</td>
</tr>
<tr><td><code>group_exe</code></td><td><code>010</code></td><td>   <code>S_IXGRP</code></td>
  <td> Execute/search permission, group</td>
</tr>
<tr><td><code>group_all</code></td><td><code>070</code></td><td>   <code>S_IRWXG</code></td>
  <td> Read, write, execute/search by group; <code>group_read | group_write | group_exe</code></td>
</tr>
<tr><td><code>others_read</code></td><td><code>04</code></td><td>  <code>S_IROTH</code></td>
  <td> Read permission, others</td>
</tr>
<tr><td><code>others_write</code></td><td><code>02</code></td><td> <code>S_IWOTH</code></td>
  <td> Write permission, others</td>
</tr>
<tr><td><code>others_exe</code></td><td><code>01</code></td><td>   <code>S_IXOTH</code></td>
  <td> Execute/search permission, others</td>
</tr>
<tr><td><code>others_all</code></td><td><code>07</code></td><td>   <code>S_IRWXO</code></td>
  <td>Read, write, execute/search by others; <code>others_read | others_write | others_exe</code></td>
</tr>
<tr><td><code>all_all</code></td><td><code>0777</code></td><td> </td><td><code>owner_all | group_all | others_all</code></td>
</tr>
<tr><td><code>set_uid_on_exe</code></td><td><code>04000</code></td><td> <code>S_ISUID</code></td>
  <td> Set-user-ID on execution</td>
</tr>
<tr><td><code>set_gid_on_exe</code></td><td><code>02000</code></td><td> <code>S_ISGID</code></td>
  <td> Set-group-ID on execution</td>
</tr>
<tr><td><code><a name="sticky_bit">sticky_bit</a> </code></td><td><code>01000</code></td><td> <code>S_ISVTX</code></td>
  <td> Operating system dependent. Inherently non-portable, even between ISO/IEC 9945 
  operating systems.</td>
</tr>
<tr><td><code><a name="perms_mask">perms_mask</a></code></td><td><code>07777</code></td><td> &nbsp;</td>
  <td><code>all_all | set_uid_on_exe | set_gid_on_exe | sticky_bit</code></td>
</tr>
<tr><td><code>perms_not_known</code></td><td><code>0xFFFF</code></td><td></td><td> 
  The permissions are not known, such as when a <code>file_status</code> object 
  is created without specifying the permissions</td>
</tr>
<tr><td>
  <p><code>add_perms</code></td><td><code>0x1000</code></td><td></td><td>
  <p><code>permissions()</code> adds the argument permission bits to the 
  file's current bits</td>
</tr>
<tr><td><code>remove_perms</code></td><td><code>0x2000</code></td><td></td><td>
  <code>permissions()</code> removes the argument permission bits from the 
  file's current bits</td>
</tr>
<tr><td><code><a name="symlink_perms">symlink_perms</a></code></td><td><code>0x4000</code></td><td></td><td>
  <span style="background-color: #FFFF00">On ISO/</span><span style="background-color: #FFFF00">IEC</span><span style="background-color: #FFFF00"> 9945
  </span> <code><span style="background-color: #FFFF00">permissions()</span></code><span style="background-color: #FFFF00"> resolves symlinks unless
  </span> <code><span style="background-color: #FFFF00">symlink_perms</span></code><span style="background-color: #FFFF00"> is specified. 
  Meaningless on Windows as </span> <code>
  <span style="background-color: #FFFF00">permissions()</span></code><span style="background-color: #FFFF00"> never resolves symlinks. 
  Meaningless on Mac OS X and some other BSD systems as </span> <code>
  <span style="background-color: #FFFF00">permissions()</span></code><span style="background-color: #FFFF00"> always resolves symlinks. Get over it.</span></td>
</tr>

</table>
<h2><a name="file_status">Class file_status</a> [class.file_status]</h2>
<pre>namespace boost
{
  namespace filesystem
  {
      class file_status
      {
      public:

        // <a href="#file_status-constructors">constructors</a>
        file_status() noexcept;
        explicit file_status(<a href="#file_type">file_type</a> ft, <a href="#Enum-perms">perms</a> prms = perms_not_known) noexcept;

        // compiler generated
        file_status(const file_status&amp;) noexcept;
        file_status&amp; operator=(const file_status&amp;) noexcept;
       ~file_status() noexcept;

        // <a href="#file_status-observers">observers</a>
        <a href="#file_type">file_type</a>  type() const noexcept;
        <a href="#Enum-perms">perms</a>      permissions() const noexcept;

        // <a href="#file_status-modifiers">modifiers</a>
        void       type(<a href="#file_type">file_type</a> ft) noexcept;
        void       permissions(<a href="#Enum-perms">perms</a> prms) noexcept;
      };
  }  // namespace filesystem
}  // namespace boost</pre>
<p>An object of type <code>file_status</code> stores information about the type 
and permissions of a file.</p>
<h3><a name="file_status-constructors"><code>file_status</code> constructors</a> 
[file_status.cons]</h3>
<pre>explicit file_status() noexcept;</pre>
<blockquote>
  <p><i>Postconditions:</i> <code>type() == status_error</code>, <code>permissions() == perms_not_known</code>.</p>
</blockquote>
<pre>explicit file_status(<a href="#file_type">file_type</a> ft, <a href="#Enum-perms">perms</a> prms = perms_not_known) noexcept;</pre>
<blockquote>
  <p><i>Postconditions:</i> <code>type() == ft</code>, <code>permissions() == prms</code>.</p>
</blockquote>
  <h3><a name="file_status-observers"><code>file_status</code> observers</a> [file_status.obs]</h3>
<pre><a href="#file_type">file_type</a> type() const noexcept;</pre>
<blockquote>
  <p><i>Returns: </i>The value of <code>type()</code> specified by the <i>postconditions</i> of the most recent call to a constructor, operator=, or <code>type(file_type)</code> function.</p>
</blockquote>
<pre><a href="#Enum-perms">perms</a> permissions() const noexcept;</pre>
<blockquote>
  <p><i>Returns: </i>The value of <code>permissions()</code> specified by the <i>postconditions</i> of the most recent call to a constructor, operator=, or <code>permissions(perms)</code> function.</p>
</blockquote>
<h3><a name="file_status-modifiers"><code>file_status</code> modifiers</a> [file_status.mods]</h3>
<pre>void type(<a href="#file_type">file_type</a> ft) noexcept;</pre>
<blockquote>
  <p><i>Postconditions:</i> <code>type() == ft</code>.</p>
</blockquote>
<pre>void permissions(<a href="#Enum-perms">perms</a> prms) noexcept;</pre>
<blockquote>
  <p><i>Postconditions:</i> <code>permissions() == prms</code>.</p>
</blockquote>
<h2><a name="Class-directory_entry">Class <code>directory_entry</code></a> [class.directory_entry]</h2>

<pre>namespace boost
{
  namespace filesystem
  {
      class directory_entry
      {
      public:

        // <a href="#directory_entry-constructors">constructors</a> and destructor
        directory_entry();
        directory_entry(const directory_entry&amp;);
        explicit directory_entry(const path&amp; p, file_status st=file_status(),
          file_status symlink_st=file_status());
       ~directory_entry(); 

        // <a href="#directory_entry-modifiers">modifiers</a>
        directory_entry&amp; operator=(const directory_entry&amp;);
        void assign(const path&amp; p, file_status st=file_status(),
          file_status symlink_st=file_status());
        void replace_filename(const path&amp; p, file_status st=file_status(),
          file_status symlink_st=file_status());

        // <a href="#directory_entry-observers">observers</a>
        const path&amp;  path() const;
        file_status  status() const;
        file_status  status(system::error_code&amp; ec) const;
        file_status  symlink_status() const;
        file_status  symlink_status(system::error_code&amp; ec) const;

        bool operator&lt; (const directory_entry&amp; rhs);
        bool operator==(const directory_entry&amp; rhs); 
        bool operator!=(const directory_entry&amp; rhs); 
        bool operator&lt; (const directory_entry&amp; rhs);
        bool operator&lt;=(const directory_entry&amp; rhs);
        bool operator&gt; (const directory_entry&amp; rhs);
        bool operator&gt;=(const directory_entry&amp; rhs);
      private:
        path                 m_path;           // for exposition only
        mutable file_status  m_status;         // for exposition only; stat()-like
        mutable file_status  m_symlink_status; // for exposition only; lstat()-like
      };

  }  // namespace filesystem
}  // namespace boost</pre>

<p>A <code>directory_entry</code> object stores a <code>path object</code>, 
a <code>file_status</code> object for non-symbolic link status, and a <code>file_status</code> object for symbolic link status. The <code>file_status</code> objects act as value caches.</p>
<blockquote>
<p>[<i>Note:</i> Because <code>status()</code>on a pathname may be a relatively expensive operation, 
some operating systems provide status information as a byproduct of directory 
iteration. Caching such status information can result is significant time savings. Cached and 
non-cached results may differ in the presence of file system races. <i>—end note</i>]</p>
<p><span style="background-color: #E0E0E0"><i>Actual cold-boot timing of iteration over 
a directory with 15,047 entries was six seconds for non-cached status queries 
versus one second for cached status queries. Windows XP, 3.0 GHz processor, with 
a moderately fast hard-drive. Similar speedups are expected on Linux and BSD-derived 
systems that provide status as a by-product of directory iteration.</i></span></p>
</blockquote>
<h3> <a name="directory_entry-constructors"> <code>directory_entry </code>constructors</a> 
[directory_entry.cons]</h3>
<pre>directory_entry();</pre>
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="36%">
    <tr>
      <td width="18%"><b>Expression</b></td>
      <td width="82%"><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%"><code>path().empty()</code></td>
      <td width="82%"><code>true</code></td>
    </tr>
    <tr>
      <td width="18%"><code>status()</code></td>
      <td width="82%"><code>file_status()</code></td>
    </tr>
    <tr>
      <td width="18%"><code>symlink_status()</code></td>
      <td width="82%"><code>file_status()</code></td>
    </tr>
  </table>
</blockquote>
<pre>explicit directory_entry(const path&amp; p, file_status st=file_status(), file_status symlink_st=file_status());</pre>
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="36%">
    <tr>
      <td width="18%"><b>Expression</b></td>
      <td width="82%"><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%"><code>path()</code></td>
      <td width="82%"><code>p</code></td>
    </tr>
    <tr>
      <td width="18%"><code>status()</code></td>
      <td width="82%"><code>st</code></td>
    </tr>
    <tr>
      <td width="18%"><code>symlink_status()</code></td>
      <td width="82%"><code>symlink_st</code></td>
    </tr>
  </table>
</blockquote>
<h3> <a name="directory_entry-modifiers"> <code>directory_entry </code>modifiers</a> 
[directory_entry.mods]</h3>
<pre>void assign(const path&amp; p, file_status st=file_status(), file_status symlink_st=file_status());</pre>
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="36%">
    <tr>
      <td width="18%"><b>Expression</b></td>
      <td width="82%"><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%"><code>path()</code></td>
      <td width="82%"><code>p</code></td>
    </tr>
    <tr>
      <td width="18%"><code>status()</code></td>
      <td width="82%"><code>st</code></td>
    </tr>
    <tr>
      <td width="18%"><code>symlink_status()</code></td>
      <td width="82%"><code>symlink_st</code></td>
    </tr>
  </table>
</blockquote>
<pre>void replace_filename(const path&amp; p, file_status st=file_status(), file_status symlink_st=file_status());</pre>
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="43%">
    <tr>
      <td width="18%"><b>Expression</b></td>
      <td width="82%"><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%"><code>path()</code></td>
      <td width="82%"><code>path().branch() / s</code></td>
    </tr>
    <tr>
      <td width="18%"><code>status()</code></td>
      <td width="82%"><code>st</code></td>
    </tr>
    <tr>
      <td width="18%"><code>symlink_status()</code></td>
      <td width="82%"><code>symlink_st</code></td>
    </tr>
  </table>
</blockquote>
<h3> <a name="directory_entry-observers"> <code>directory_entry</code> observers</a> 
[directory_entry.obs]</h3>
<pre>const path&amp; path() const;</pre>
<blockquote>
  <p><i>Returns:</i> <code>m_path</code></p>
</blockquote>
<pre>file_status status() const;
file_status status(system::error_code&amp; ec) const;</pre>
<blockquote>
<p><i>Effects:</i> As if,</p>
  <blockquote>
    <pre>if ( !status_known( m_status ) )
{
  if ( status_known(m_symlink_status) &amp;&amp; !is_symlink(m_symlink_status) )
    { m_status = m_symlink_status; }
  else { m_status = status(m_path<i>[, ec]</i>); }
}</pre>
  </blockquote>
  <p><i>Returns:</i> <code>m_status</code></p>
  
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  
</blockquote>
<pre>file_status  symlink_status() const;
file_status  symlink_status(system::error_code&amp; ec) const;</pre>
<blockquote>
<p>
  <i>Effects:</i> As if,</p>
  <blockquote>
    <pre>if ( !status_known( m_symlink_status ) )
{
  m_symlink_status = symlink_status(m_path<i>[, ec]</i>);
}</pre>
  </blockquote>
  <p><i>Returns:</i> <code>m_symlink_status</code></p>
  
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  
</blockquote>
<pre>bool operator==(const directory_entry&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>m_path == rhs.m_path</code>.</p>
</blockquote>
<pre>bool operator!=(const directory_entry&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>m_path != rhs.m_path</code>.</p>
</blockquote>
<pre>bool operator&lt; (const directory_entry&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>m_path &lt; rhs.m_path</code>.</p>
</blockquote>
<pre>bool operator&lt;=(const directory_entry&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>m_path &lt;= rhs.m_path</code>.</p>
</blockquote>
<pre>bool operator&gt; (const directory_entry&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>m_path &gt; rhs.m_path</code>.</p>
</blockquote>
<pre>bool operator&gt;=(const directory_entry&amp; rhs);</pre>
<blockquote>
  <p><i>Returns:</i> <code>m_path &gt;= rhs.m_path</code>.</p>
</blockquote>
<h2><a name="Class-directory_iterator">Class <code>directory_iterator</code> 
[class.directory_iterator]</a></h2>
<p>Objects of type <code>directory_iterator</code> provide standard library 
compliant iteration over the contents of a directory. Also see class <code><a href="#Class-recursive_directory_iterator">recursive_directory_iterator</a></code>.</p>
<pre>namespace boost
{
  namespace filesystem
  {
      class directory_iterator
      {
      public:
        // <a href="#directory_iterator-members">member functions</a>

        directory_iterator() noexcept;  // creates the &quot;end&quot; iterator
        directory_iterator(const directory_iterator&amp;);
        explicit directory_iterator(const path&amp; p);
        directory_iterator(const path&amp; p, system::error_code&amp; ec);
       ~directory_iterator();

        directory_iterator&amp; operator=(const directory_iterator&amp;);

        directory_iterator&amp; operator++();
        directory_iterator&amp; increment(system::error_code&amp; ec);

        // other members as required by
        //  C++ Std, 24.1.1 Input iterators [input.iterators]
      };

  }  // namespace filesystem
}  // namespace boost</pre>
<p> <code>directory_iterator</code> satisfies the requirements of an 
input iterator (C++ Std, 24.2.1, Input iterators [input.iterators]).</p>
<p>A <code>directory_iterator</code> reads successive elements from the directory for 
which it was constructed, as if by calling ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/readdir_r.html">readdir_r()</a></code>. After a <code>directory_iterator</code> is constructed, and every time <code>operator++</code> is called, 
it reads a directory element and stores information about it in a object of type <code><a href="#Class-directory_entry">directory_entry</a></code>. <code>operator++</code> is not equality preserving; that is, <code>i == j</code> does not imply that <code>++i == ++j</code>. </p>
<blockquote>
<p>[<i>Note:</i> The practical consequence of not preserving equality is that directory iterators 
can only be used for single-pass algorithms. <i>—end note</i>]</p>
</blockquote>
<p>If the end of the directory elements is reached, the iterator shall become equal to 
the end iterator value. The constructor <code>directory_iterator()</code> with no arguments always constructs an end iterator object, which 
shall be the only valid iterator for the end condition. The result of <code>operator*</code> on an end iterator is not defined. For any other iterator value 
a <code>const directory_entry&amp;</code> is returned. The result of <code>operator-&gt;</code> on an end iterator is 
undefined behavior. For any other iterator value a <code>const directory_entry*</code> is 
returned. </p>
<p>Two end iterators are always equal. An end iterator shall not be equal to a non-end 
iterator.</p>
<blockquote>
<p><i><span style="background-color: #E0E0E0">The above wording is based on the 
Standard Library's istream_iterator wording.</span></i></p>
</blockquote>
<p>The result of calling the <code>path()</code> member of the <code>directory_entry</code> object obtained by dereferencing a <code>directory_iterator</code> is a reference to a <code>path</code> object composed of the directory argument from which the iterator was 
constructed with filename of the directory entry appended as if by <code>operator/=</code>. </p>
<p>Directory iteration shall not yield directory entries for the current (<i>dot</i>) 
and parent (<i>dot dot</i>) directories.</p>
<p>The order of directory entries obtained by dereferencing successive 
increments of a <code>directory_iterator</code> is unspecified.</p>
<blockquote>
<p>[<i>Note:</i> Programs performing directory iteration may wish to test if the 
path obtained by dereferencing a directory iterator actually exists. It could be 
a
symbolic link to a non-existent file. Programs recursively 
walking directory trees for purposes of removing and renaming entries may wish 
to avoid following symbolic links.</p>
<p>If a file  is removed from or added to a directory after the 
construction of a <code>directory_iterator</code> for the directory, it is 
unspecified whether or not subsequent incrementing of the iterator will ever 
result in an iterator whose value is the removed or added directory entry. See
ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/readdir_r.html">readdir_r()</a></code>. <i>—end note</i>]</p>
</blockquote>
<h3><a name="directory_iterator-members"><code>directory_iterator</code> members</a> 
[directory_iterator.members]</h3>

<p><code><a name="directory_iterator-default-ctor">directory_iterator</a>() 
noexcept;</code></p>

<blockquote>

<p><i>Effects:</i> Constructs the end iterator.</p>

</blockquote>

<pre><code>explicit <a name="directory_iterator-ctor-path">directory_iterator</a>(</code>const path&amp; p<code>);
directory_iterator(</code>const path&amp; p, system::error_code&amp; ec<code>);</code></pre>
<blockquote>

<p><i>Effects:</i> Constructs a iterator representing the first 
entry in the directory <code>p</code> resolves to, if any; otherwise, the end iterator.</p>

<p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>

<p>[<i>Note:</i> To iterate over the current directory, use <code>directory_iterator(&quot;.&quot;)</code> rather than <code>directory_iterator(&quot;&quot;)</code>. <i>—end note</i>]</p>
</blockquote>
<pre>directory_iterator&amp; <a name="directory_iterator-increment">operator++</a>();
directory_iterator&amp; increment(system::error_code&amp; ec);</pre>
<blockquote>

<p><i>Effects:</i> As specified by the C++ Standard, 24.1.1 Input iterators [input.iterators]</p>

<p><i>Returns:</i> <code>*this</code>.</p>

<p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>

</blockquote>
<h3><a name="directory_iterator-non-member-functions"><code>directory_iterator</code> non-member functions</a></h3>
<pre>const directory_iterator&amp; begin(const directory_iterator&amp; iter);</pre>
<blockquote>
  <p><i>Returns: </i><code>iter</code>.</p>
</blockquote>
<pre>directory_iterator end(const directory_iterator&amp;);</pre>
<blockquote>
  <p><i>Returns: </i><code>directory_iterator()</code>.</p>
</blockquote>
<h2><a name="Class-recursive_directory_iterator">Class <code>recursive_directory_iterator</code> 
[class.rec.dir.itr]</a></h2>
<p>Objects of type <code>recursive_directory_iterator</code> provide standard library 
compliant iteration over the contents of a directory, including recursion into 
its sub-directories.</p>
<pre>namespace boost
{
  namespace filesystem
  {
      class recursive_directory_iterator :
        public iterator&lt;input_iterator_tag, directory_entry&gt;
      {
      public:

        // constructors and destructor
        recursive_directory_iterator() noexcept;
        recursive_directory_iterator(const recursive_directory_iterator&amp;);
        explicit recursive_directory_iterator(const path&amp; p,
          <a href="#symlink_option">symlink_option</a> opt = symlink_option::none);
        recursive_directory_iterator(const path&amp; p,
          <a href="#symlink_option">symlink_option</a> opt, system::error_code&amp; ec);
        recursive_directory_iterator(const path&amp; p, system::error_code&amp; ec);
       ~recursive_directory_iterator();

        // observers
        int level() const noexcept;
        bool no_push<code>_pending</code>() const noexcept;

        // modifiers
        recursive_directory_iterator&amp; operator=(const recursive_directory_iterator&amp;);

        recursive_directory_iterator&amp; operator++();
        recursive_directory_iterator&amp; increment(system::error_code&amp; ec);

        void pop();
        void no_push(bool value=true);

        // other members as required by
        //  C++ Std, Input iterators [input.iterators]

      private:
<i><b>        // actual data members will probably be stored in a shared object,
        // or some similar mechanism, to achieve the required input iterator
        // copy semantics
</b></i>        int            m_level; <b><i>   // for exposition only</i></b>
        bool           m_no_<code>push</code>;  <i><b>// for exposition only
        </b></i><a href="#symlink_option">symlink_option</a> m_options;  <i><b>// for exposition only</b></i>
      };

  }  // namespace filesystem
}  // namespace boost</pre>

<p>The behavior of a <code>recursive_directory_iterator</code> is the same 
as a <code>directory_iterator</code> unless otherwise specified.</p>
<ul>
  <li>Incrementing a <code>recursive_directory_iterator</code> pointing to a 
  directory causes that directory itself to be iterated over, as specified by 
  the <code>operator++</code> and <code>increment</code> functions.<br>
&nbsp;</li>
  <li>When a <code>recursive_directory_iterator</code> reaches the end of the directory currently being iterated 
  over, or when <code>pop()</code> is called, <code>m_level</code> is 
  decremented, and iteration of the parent directory continues.</li>
</ul>
<pre>recursive_directory_iterator() noexcept;</pre>
<blockquote>

<p><i>Effects:</i> Constructs the end iterator.</p>

</blockquote>

<pre>explicit recursive_directory_iterator(const path&amp; p, <a href="#symlink_option">symlink_option</a> opt = symlink_option::none);
recursive_directory_iterator(const path&amp; p, <a href="#symlink_option">symlink_option</a> opt, system::error_code&amp; ec);
recursive_<code>directory_iterator(</code>const path&amp; p, system::error_code&amp; ec<code>);</code></pre>
<blockquote>

<p><i>Effects:</i>&nbsp; Constructs a iterator representing the first 
entry in the directory <code>p</code> resolves to, if any; otherwise, the end iterator.</p>

<p><i>Postcondition: </i>Unless the end iterator was constructed,<i> </i><code>level() == 0 &amp;&amp; no_push_pending() == false &amp;&amp; m_options == opt</code>. 
For the signature without a <code>symlink_option</code> argument, <code>opt</code> is assumed to be <code>symlink_option::none</code>.</p>

<p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>

<p>[<i>Note:</i> To iterate over the current directory, use <code>recursive_directory_iterator(&quot;.&quot;)</code> rather than <code>recursive_directory_iterator(&quot;&quot;)</code>. <i>—end note</i>]</p>

<p>[<i>Note:</i> By default, <code>recursive_directory_iterator</code> does not 
follow directory symlinks. To follow directory symlinks, specify <code>opt</code> as <code>symlink_option::recurse</code> <i>—end note</i>]</p>
</blockquote>
<pre>int level() const noexcept;</pre>
<blockquote>
  <p><i>Requires:</i> <code>*this != recursive_directory_iterator()</code>.</p>
  <p><i>Returns:</i> <code>m_level</code>.</p>
</blockquote>
<pre>bool <code>no_push_pending</code>() const noexcept;</pre>
<blockquote>
  <p><i>Requires:</i> <code>*this != recursive_directory_iterator()</code>.</p>
  <p><i>Returns:</i> <code>m_no_push</code>.</p>
</blockquote>
<pre><code>recursive_directory_iterator</code>&amp; <a name="recursive_directory_iterator-increment">operator++</a>();
recursive_directory_iterator&amp; increment(system::error_code&amp; ec);</pre>
<blockquote>

<p><i>Effects:</i> As specified by the C++ Standard, 24.1.1 Input iterators [input.iterators], 
except:</p>

<ul>
  <li>

<p>if <code>!no_push_pending() &amp;&amp; is_directory(this-&gt;status()) 
&amp;&amp; (!is_symlink(this-&gt;symlink_status()) || (m_options &amp; symlink_option::recurse) != 0)</code> then&nbsp; <code>m_level</code> is incremented and directory <code>(*this)-&gt;path()</code> is recursively iterated into.<br>
&nbsp;</p>

  </li>
  <li>if there are no more directory entries at this level then <code>m_level</code> 
is decremented and iteration of the parent directory resumes.</li>
</ul>

<p><i>Postcondition:</i> <code>no_push_pending() == false</code>.</p>

<p><i>Returns:</i> <code>*this</code>.</p>

<p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>

</blockquote>
<pre>void pop();</pre>
<blockquote>
  <p><i>Requires:</i> <code>*this != recursive_directory_iterator()</code>.</p>
  <p><i>Effects:</i> If <code>level() == 0</code>, set <code>*this</code> to <code>recursive_directory_iterator()</code>. 
  Otherwise, <code>--m_level</code>, cease iteration of the directory currently being 
  iterated over, and continue iteration over the parent directory.</p>
</blockquote>
<pre>void no_push(bool value=true);</pre>
<blockquote>
  <p><i>Requires:</i> <code>*this != recursive_directory_iterator()</code>.</p>
<p><i>Postcondition:</i> <code>no_push_pending() == value</code>.</p>
  <p>[<i>Note:</i> <code>no_push()</code> is used to prevent 
  unwanted recursion into a directory. <i>—end note</i>]</p>
</blockquote>
<h3><a name="recursive_directory_iterator-non-member-functions"><code>recursive_directory_iterator</code> non-member functions</a></h3>
<pre>const recursive_directory_iterator&amp; begin(const recursive_directory_iterator&amp; iter);</pre>
<blockquote>
  <p><i>Returns: </i><code>iter</code>.</p>
</blockquote>
<pre>recursive_directory_iterator end(const recursive_directory_iterator&amp;);</pre>
<blockquote>
  <p><i>Returns: </i><code>recursive_directory_iterator()</code>.</p>
</blockquote>
<h2><a name="Operational-functions">Operational functions</a> [fs.op.funcs]</h2>
<p>Operational functions query or modify files, including directories, in external 
storage.</p>
<p>Operational functions access a file by resolving an 
object of class <code>path</code> to a particular file in a file hierarchy. The 
path is resolved as if by the ISO/IEC 9945 <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap04.html#tag_04_11">Pathname Resolution</a> mechanism.</p>
<p>[<i>Note: </i>Because hardware failures, network failures, <a href="#file-system-race">file system races</a>, and many 
other kinds of errors occur frequently in file system operations, users should be aware 
that any filesystem operational function, no matter how apparently innocuous, may encounter 
an error.&nbsp;See <a href="#Error-reporting">Error reporting</a>. <i>—end note</i>]</p>
<pre>path <a name="absolute">absolute</a>(const path&amp; p, const path&amp; base=current_path());</pre>
  <blockquote>
  <p><i>Returns:</i> A <a href="#Absolute-path">absolute path</a> composed according to the 
  following table</p>
  <table border="1" cellpadding="5" cellspacing="0" bordercolor="#111111" style="border-collapse: collapse">
    <tr>
      <td align="center">&nbsp;</td>
      <td align="center"><b><code>p.<br>
      has_root_directory()</code></b></td>
      <td align="center"><b><code>!p.has_root_directory()</code></b></td>
    </tr>
    <tr>
      <td align="center"><b><code>p.has_root_name()</code></b></td>
      <td align="left"><code>return p</code></td>
      <td align="left"><code>return<br>
&nbsp;p.root_name()<br>
&nbsp;/ absolute(base)<br>
&nbsp;&nbsp;&nbsp; .root_directory()<br>
      &nbsp;/ absolute(base)<br>
&nbsp;&nbsp;&nbsp; .relative_path()<br>
&nbsp;/ p.relative_path()</code></td>
    </tr>
    <tr>
      <td align="center"><b><code>!p.has_root_name()</code></b></td>
      <td align="left"><code>return<br>
&nbsp;absolute(base)<br>
&nbsp; .root_name()<br>
      &nbsp;/ p</code></td>
      <td align="left"><code>return absolute(base)<br>
&nbsp;/ p</code></td>
    </tr>
  </table>
  <p>[<i>Note:</i> For the returned path, <code>rp,</code> <code>rp.is_absolute()</code> is true. <i>—end note</i>]</p>
  <p><i>Throws:</i> If <code>base.is_absolute()</code> is true, throws only if 
  memory allocation fails.</p>
</blockquote>
<pre>path <a name="canonical">canonical</a>(const path&amp; p, const path&amp; base = current_path());
path canonical(const path&amp; p, system::error_code&amp; ec);
path canonical(const path&amp; p, const path&amp; base, system::error_code&amp; ec);</pre>
<blockquote>
<p><i>Overview:</i> Converts <code>p</code>, which must exist, to an absolute 
path that has no symbolic link, <a href="#Dot">dot</a>, 
or <a href="#Dot">dot-dot</a> elements. </p>
<p><i>Returns:</i> A <a href="#canonical-path">canonical path</a> that refers to 
the same file system object as <code>absolute(p,base)</code>. For the overload 
without a <code>base</code> argument, <code>base</code> is <code>current_path()</code>.</p>
  <p><i>Throws:</i>&nbsp; As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  
  <p><i>Remarks:</i> <code>!exists(p)</code> is an error.</p>
  
  <p>[<i>Note:</i> Canonical pathnames allow security checking of a path (eg. 
  does this path live in /home/goodguy or /home/badguy?)&nbsp; —end note]</p>
  
</blockquote>
<pre>void <a name="copy">copy</a>(const path&amp; from, const path&amp; to);
void copy(const path&amp; from, const path&amp; to, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> As if</p>
  
  <blockquote>
    <pre>file_status s(symlink_status(from<i>[</i><code>, ec</code><i>]</i>));
if(is_symlink(s))
  copy_symlink(from, to<i>[</i><code>, ec</code><i>]</i>);
else if(is_directory(s))
  copy_directory(from, to<i>[</i><code>, ec</code><i>]</i>);
else if(is_regular_file(s))
  copy_file(from, to, copy_option::fail_if_exists<i>[</i><code>, ec</code><i>]</i>);
else
<i> Report error as specified in <a href="#Error-reporting">Error reporting</a>.</i></pre>
  </blockquote>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  
</blockquote>
<pre>void <a name="copy_directory">copy_directory</a>(const path&amp; from, const path&amp; to);
void copy_directory(const path&amp; from, const path&amp; to, system::error_code&amp; ec);</pre>
<blockquote>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse"
   bordercolor="#111111" width="90%" bgcolor="#E0E0E0">
    <tr>
      <td width="100%">
      <p><i>This function is poorly named; it should probably be an overload of
      <code>create_directory</code> with an additional argument.</i></td>
    </tr>
  </table>
  
  <p><i>Effects: </i>Creates directory <code>to</code>, with 
  attributes copied from directory <code>from</code>. The set of attributes 
  copied is operating system dependent.</p>
  
<blockquote>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse"
   bordercolor="#111111" width="90%" bgcolor="#E8FFE8">
    <tr>
      <td width="100%">
      <p>[<i>Note:</i> For ISO 9945/POSIX based operating systems the 
      attributes are those copied by native API <code>stat(from.c_str(), &amp;from_stat)</code> 
      followed by <code>mkdir(to.c_str(),from_stat.st_mode)</code>.&nbsp; For 
      Windows based operating systems the attributes are those copied by native 
      API <code>CreateDirectoryExW(from.c_str(), to.c_str(), 0)</code>.&nbsp; <i>
      —end note</i>]</td>
    </tr>
  </table>
</blockquote>
  
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>

</blockquote>

<pre>void copy_file(const path&amp; from, const path&amp; to);
void copy_file(const path&amp; from, const path&amp; to, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects: </i><code>copy_file(from, to, copy_option::fail_if_exists</code><i>[</i><code>, ec</code><i>]</i><code>)</code>.</p>
  
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  
</blockquote>
<pre>void <a name="copy_file">copy_file</a>(const path&amp; from, const path&amp; to, <a href="#copy_option">copy_option</a> option);
void <a name="copy_file2">copy_file</a>(const path&amp; from, const path&amp; to, <a href="#copy_option">copy_option</a> option, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> If <code>option == copy_option::</code><code>fail_if_exists &amp;&amp; exists(to)</code>, an error is reported. Otherwise, the contents and attributes of the file <code>from</code> resolves to are copied to the file <code>to</code> resolves to.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre>void <a name="copy_symlink">copy_symlink</a>(const path&amp; existing_symlink, const path&amp; new_symlink);
void copy_symlink(const path&amp; existing_symlink, const path&amp; new_symlink, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects: </i><code>create_symlink(read_symlink(existing_symlink</code><i>[</i><code>, ec</code><i>]</i><code>), new_symlink</code><i>[</i><code>, ec</code><i>]</i><code>)</code>.</p>
  
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  
</blockquote>
<pre>bool <a name="create_directories">create_directories</a>(const path&amp; p);
bool <a name="create_directories2">create_directories</a>(const path&amp; p, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> Establishes the postcondition by calling <code>
  create_directory()</code> for any element of <code>p</code> that does not 
  exist.</p>
  <p><i>Postcondition:</i> <code>is_directory(p)</code></p>
  <p><i>Returns:</i> <code>true</code> if a new directory was created, otherwise <code>
  false</code>.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p><i>Complexity:</i> <i>O(n+1)</i> where <i>n</i> is the number of elements 
  of <code>p</code> that do not exist.</p>
</blockquote>
<pre>bool <a name="create_directory">create_directory</a>(const path&amp; p);
bool <a name="create_directory2">create_directory</a>(const path&amp; p, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> Establishes the postcondition by attempting to create the 
  directory <code>p</code> resolves to, as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/mkdir.html">
  mkdir()</a></code> with a second argument of S_IRWXU|S_IRWXG|S_IRWXO. Creation 
  failure because <code>p</code> resolves to an existing directory shall not be 
  treated as an error. </p>
  <p><i>Postcondition:</i> <code>is_directory(p)</code></p>
  <p><i>Returns:</i> <code>true</code> if a new directory was created, otherwise <code>false</code>.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre>void <a name="create_directory_symlink">create_directory_symlink</a>(const path&amp; to, const path&amp; new_symlink);
void create_directory_symlink(const path&amp; to, const path&amp; new_symlink, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> Establishes the postcondition, as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/symlink.html">symlink()</a></code>.</p>
  <p><i>
  Postcondition:</i> <code>new_symlink</code> resolves to a symbolic link file that 
  contains an unspecified representation of <code>to</code>.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p>[<i>Note:</i> Some operating systems, such as Windows, require symlink creation to 
  identify that the link is to a directory. Portable code should use <code>create_directory_symlink()</code> to create directory symlinks rather than <code>create_symlink()</code> <i>—end note</i>]</p>
  <p>[<i>Note:</i> Some operating systems do not support symbolic links at all or support 
  them only for regular files. 
  Some file systems do not 
  support 
  symbolic links regardless of the operating system - the FAT file system used on 
  memory cards and flash drives, for example. <i>—end note</i>]</p>
  </blockquote>
<pre>void <a name="create_hard_link">create_hard_link</a>(const path&amp; to, const path&amp; new_hard_link);
void <a name="create_hard_link2">create_hard_link</a>(const path&amp; to, const path&amp; new_hard_link, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> Establishes the postcondition, as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/link.html">link()</a></code>.</p>
  <p><i>Postcondition:</i></p>
  <ul>
    <li>&nbsp;<code>exists(to) &amp;&amp; 
    exists(</code><code>new_hard_link</code><code>) &amp;&amp; equivalent(to, 
     
    </code><code>new_hard_link</code><code>)</code></li>
    <li>The contents of the file or directory
    <code>to</code> resolves to are unchanged.</li>
  </ul>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p>[<i>Note:</i> Some operating systems do not support hard links at all or support 
  them only for regular files. Some file systems do not support hard 
  links regardless of the operating system - the FAT file system used on memory 
  cards and flash drives, for example. Some file systems limit the number of 
  links per file. <i>—end note</i>]</p>
  </blockquote>
<pre>void <a name="create_symlink">create_symlink</a>(const path&amp; to, const path&amp; new_symlink);
void <a name="create_symlink2">create_symlink</a>(const path&amp; to, const path&amp; new_symlink, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> Establishes the postcondition, as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/symlink.html">symlink()</a></code>.</p>
  <p><i>
  Postcondition:</i> <code>new_symlink</code> resolves to a symbolic link file that 
  contains an unspecified representation of <code>to</code>.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p>[<i>Note:</i> Some operating systems do not support symbolic links at all or support 
  them only for regular files. 
  Some file systems do not 
  support 
  symbolic links regardless of the operating system - the FAT system used on 
  memory cards and flash drives, for example. <i>—end note</i>]</p>
  </blockquote>
<pre>path <a name="current_path">current_path</a>();
path <a name="current_path2">current_path</a>(system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Returns:</i> The current working directory path, as if by ISO/IEC  
  9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/getcwd.html">getcwd()</a></code>. <code>is_absolute()</code> is true for the returned path.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p>[<i>Note: </i>The <code>current_path()</code> name was chosen to emphasize that the return is a 
  path, not just a single directory name.</p>
  <p>The current path as returned by many operating systems is a dangerous 
  global variable. It may be changed unexpectedly by a third-party or system 
  library functions, or by another thread.&nbsp; <i>—end note</i>]</p>
</blockquote>
<pre>void current_path(const path&amp; p);
void current_path(const path&amp; p, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> Establishes the postcondition, as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/chdir.html">chdir()</a></code>.</p>
<p><i>Postcondition:</i> <code>equivalent(p, current_path())</code>.</p>
<p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p>[<i>Note: </i>The current path for many operating systems is a dangerous 
  global state. It may be changed unexpectedly by a third-party or system 
  library functions, or by another thread.&nbsp; <i>—end note</i>]</p>
</blockquote>
<pre>bool <a name="exists">exists</a>(file_status s) noexcept;</pre>
<blockquote>
  <p><i>Returns:</i> <code>status_known(s) &amp;&amp; s.type() != file_not_found</code></p>
</blockquote>
<pre>bool <a name="exists2">exists</a>(const path&amp; p);
bool <a name="exists3">exists</a>(const path&amp; p, system::error_code&amp; ec) noexcept;</pre>
<blockquote>
  <p><i>Returns:</i> <code>exists(status(p))</code> or <code>exists(status(p, ec))</code>, 
  respectively. If ec != 0 and an error</p>
<p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre><code>bool <a name="equivalent">equivalent</a>(const path&amp; p1, const path&amp; p2);
bool <a name="equivalent2">equivalent</a>(const path&amp; p1, const path&amp; p2, system::error_code&amp; ec);</code></pre>
<blockquote>
  <p><i>Effects:</i> Determines <code>file_status s1</code> and <code>s2</code>, as if by <code>status(p1)</code> and&nbsp; <code>status(p2)</code>, 
  respectively.</p>
  <p><i>Returns:</i> <code>true</code>, if <code>sf1 == 
  sf2</code> and <code>p1</code> and <code>p2</code> resolve to the same file 
  system entity, else <code>false</code>.</p>
  <blockquote>
  <p>Two paths are considered to resolve to the same 
  file system entity if two candidate entities reside on the same device at the 
  same location. This is determined as if by the values of the ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">stat</a></code> structure<code>,</code> obtained as if by <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">stat()</a></code> for the two paths, having equal <code>st_dev</code> values 
  and equal <code>st_ino</code> values.</p>
  <p>[<i>Note:</i> ISO/IEC 9945 requires that <i>&quot;st_dev</i> must be unique within a Local Area Network&quot;. Conservative
  ISO/IEC 9945 implementations may also wish to check for equal <code>st_size</code> and <code>st_mtime</code> values. <i>Windows</i> implementations may use <code>GetFileInformationByHandle()</code> as a surrogate for <code>stat()</code>, 
  and consider &quot;same&quot; to be equal values for <code>dwVolumeSerialNumber</code>, <code>nFileIndexHigh</code>, <code>nFileIndexLow</code>, <code>nFileSizeHigh</code>, <code>nFileSizeLow</code>, <code>ftLastWriteTime.dwLowDateTime</code>, and <code>ftLastWriteTime.dwHighDateTime</code>. <i>—end note</i>]</p>
  </blockquote>
  <p><i>Throws:</i> <code>filesystem_error</code> if <code>(!exists(s1) &amp;&amp; !exists(s2)) || (is_other(s1) &amp;&amp; is_other(s2))</code>, 
  otherwise as specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>

<pre>uintmax_t <a name="file_size">file_size</a>(const path&amp; p);
uintmax_t <a name="file_size2">file_size</a>(const path&amp; p, system::error_code&amp; ec);</pre>

<blockquote>
  <p><i>Returns:</i> If <code>exists(p) &amp;&amp; is_regular_file(p)</code>, the size 
  in bytes 
  of the file <code>p</code> resolves to, determined as if by the value of 
  the ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">stat</a></code> structure member <code>st_size</code> obtained as if by
  ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">stat()</a></code>. 
  Otherwise, <code>static_cast&lt;uintmax_t&gt;(-1)</code>.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre>uintmax_t <a name="hard_link_count">hard_link_count</a>(const path&amp; p);
uintmax_t hard_link_count(const path&amp; p, system::error_code&amp; ec);</pre>
<blockquote>

  <p><i>Returns:</i> The number of hard links for <code>p</code>.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>

</blockquote>

<pre>const path&amp; <a name="initial_path">initial_path</a>();
const path&amp; <a name="initial_path2">initial_path</a>(<code>system::error_code&amp; ec</code>);</pre>
<blockquote>
  <p><i>Returns:</i> <code>current_path()</code> as of the first call to <code>initial_path()</code>.</p>
  <p>[<i>Note:</i> <code>initial_path()</code> is not thread safe, and may return an undesirable result 
  if called subsequent to a change to the current directory. These problems can 
  be avoided by calling <code>initial_path()</code> immediately on entry to 
  main().&nbsp; <i>—end note</i>]</p>
  <p><i>Throws:</i> For the first call, as specified in <a href="#Error-reporting">Error reporting</a>. Subsequent calls throw nothing.</p>
</blockquote>
<pre>bool <code><a name="is_directory">is_directory</a></code>(file_status s) noexcept;</pre>
<blockquote>
  <p><i>Returns:</i> <code>s.type() == directory_file</code></p>
</blockquote>
<pre><code>bool <a name="is_directory2">is_directory</a>(const path&amp; p);
bool <a name="is_directory3">is_directory</a>(const path&amp; p, system::error_code&amp; ec) noexcept;</code></pre>
<blockquote>
  <p><i>Returns:</i> <code>is_directory(status(p))</code> or <code>is_directory(status(p, ec))</code>, 
  respectively.</p>
<p><i>Throws:</i> <code>filesystem_error</code>; overload with <code>error_code&amp;</code> throws 
nothing.</p>
</blockquote>
<pre><code>bool <a name="is_empty">is_empty</a>(const path&amp; p);
bool <a name="is_empty2">is_empty</a></a>(const path&amp; p, system::error_code&amp; ec);</code></pre>
<blockquote>
  <p><i>Effects:</i> Determines <code>file_status s</code>, as if by <code>status(p, ec)</code>.</p>
  <p><i>Returns:</i> <code>is_directory(s)<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ? directory_iterator(p) == directory_iterator()<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; : file_size(p) == 0;</code></p>
</blockquote>
<pre>bool <code><a name="is_regular_file">is_regular_file</a></code>(file_status s) noexcept;</pre>
<blockquote>
  <p><i>Returns:</i> <code>s.type() == regular_file</code></p>
</blockquote>
<pre><code>bool <a name="is_regular_file2">is_regular_file</a>(const path&amp; p);</code></pre>
<blockquote>
  <p><i>Returns:</i> <code>is_regular_file(status(p))</code>.</p>
  <p><i>Throws:</i> <code>filesystem_error</code> if <code>status(p)</code> would throw <code>filesystem_error.</code></p>
  </blockquote>
<pre><code>bool <a name="is_regular_file3">is_regular_file</a>(const path&amp; p, system::error_code&amp; ec) noexcept;</code></pre>
<blockquote>
  <p><i>Effects:</i> Sets <code>ec</code> as if by <code>status(p, ec)</code>. [<i>Note:</i> <code>status_error</code>, <code>file_not_found</code> and <code>type_unknown</code> cases set <code>ec</code> to error values. To distinguish between cases, call the <code>status</code> function directly. <i>—end 
  note</i>] </p>
  <p><i>Returns:</i> <code>is_regular_file(status(p, ec))</code>.</p>
</blockquote>
<pre>bool <a name="is_other">is_other</a>(file_status s) noexcept;</pre>
<blockquote>
  <p><i>Returns:</i> <code>return exists(s) &amp;&amp; !is_regular_file(s) &amp;&amp; !is_directory(s) &amp;&amp; !is_symlink(s)</code></p>
</blockquote>
<pre><code>bool <a name="is_other2">is_other</a>(const path&amp; p);
bool <a name="is_other3">is_other</a>(const path&amp; p, system::error_code&amp; ec) noexcept;</code></pre>
<blockquote>
  <p><i>Returns:</i> <code>is_other(status(p))</code> or <code>is_other(status(p, ec))</code>, 
  respectively.</p>
  <p><i>Throws:</i> <code>filesystem_error</code>; overload with <code>error_code&amp;</code> throws 
  nothing.</p>
</blockquote>
<pre>bool <a name="is_symlink">is_symlink</a>(file_status s) noexcept;</pre>
<blockquote>
  <p><i>Returns:</i> <code>s.type() == symlink_file</code></p>
</blockquote>
<pre><code>bool <a name="is_symlink2">is_symlink</a>(const path&amp; p);
bool <a name="is_symlink3">is_symlink</a>(const path&amp; p, system::error_code&amp; ec) noexcept;</code></pre>
<blockquote>
  <p><i>Returns:</i> <code>is_symlink(symlink_status(p))</code> or <code>is_symlink(symlink_status(p, ec))</code>, 
  respectively.</p>
  <p><i>Throws:</i> <code>filesystem_error</code>; overload with <code>error_code&amp;</code> throws 
  nothing.</p>
</blockquote>
<pre>std::time_t <a name="last_write_time">last_write_time</a>(const path&amp; p);
std::time_t <a name="last_write_time2">last_write_time</a>(const path&amp; p<code>, system::error_code&amp; ec</code>);</pre>
<blockquote>
  <p><i>Returns:</i> The time of last data modification of <code>p</code>, determined as if by the 
  value of the ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">stat</a></code> structure member <code>st_mtime</code>&nbsp; obtained 
  as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">stat()</a></code>.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre>void <a name="last_write_time3">last_write_time</a>(const path&amp; p, const std::time_t new_time);
void <a name="last_write_time4">last_write_time</a>(const path&amp; p, const std::time_t new_time<code>, system::error_code&amp; ec</code>);</pre>
<blockquote>
  <p><i>Effects:</i> Sets the time of last data modification of the file 
  resolved to by <code>p</code> to <code>new_time</code>, as if by ISO/IEC 
  9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">stat()</a></code> followed by
  ISO/IEC 9945 <a href="http://www.opengroup.org/onlinepubs/000095399/functions/utime.html"><code>utime()</code></a>.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p>[<i>Note:</i> A postcondition of <code>last_write_time(p) == new_time</code> is not specified since it might not hold for file systems 
  with coarse time granularity. <i>—end note</i>]</p>
</blockquote>
<pre>void <a name="permissions">permissions</a>(const path&amp; p, <a href="#symlink_perms">perms</a> prms);
void permissions(const path&amp; p, <a href="#symlink_perms">perms</a> prms, system::error_code&amp; ec);</pre>
<blockquote>
  <p>
  <i>Requires:</i> <code>!((prms &amp; add_perms) &amp;&amp; (prms &amp; remove_perms))</code>.</p>
  <p><i>Effects:</i> Applies the effective permissions bits from <code>prms</code> to the file <code>p</code> resolves to, as if by
  ISO/IEC 9945 <code><a href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fchmodat.html">fchmodat()</a></code>. The effective permission bits are determined as 
  specified by the following table. </p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111">
    <tr>
      <td><b>bits present in <code>prms</code></b></td>
      <td><b>Effective bits applied</b></td>
    </tr>
    <tr>
      <td>Neither <code>add_perms</code> nor <code>remove_perms</code></td>
      <td><code>prms &amp; perms_mask</code></td>
    </tr>
    <tr>
      <td><code>add_perms</code></td>
      <td>
      <p><code>status(p).permissions() | (prms &amp; <a href="#perms_mask">perms_mask</a>)</code> </td>
    </tr>
    <tr>
      <td><code>remove_perms</code></td>
      <td><code>status(p)</code><code>.permissions() &amp; ~(prms &amp; <a href="#perms_mask">perms_mask</a>) </code></td>
    </tr>
  </table>
  <p>[<i>Note:</i> Conceptually permissions are viewed as bits, but the actual 
  implementation may use some other mechanism. -- <i>end note</i>]</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre>path <a name="read_symlink">read_symlink</a>(const path&amp; p);
path read_symlink(const path&amp; p, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Returns:</i>&nbsp; If <code>p</code> resolves to a symbolic 
  link, a <code>path</code> object containing the contents of that symbolic 
  link. Otherwise an empty <code>path</code> object.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>. [<i>Note:</i> It is an error if <code>p</code> does not 
  resolve to a symbolic link. <i>—end note</i>]</p>
</blockquote>
<pre><span style="background-color: #E8FFE8">path </span><a name="op-relative"><span style="background-color: #E8FFE8">relative</span></a><span style="background-color: #E8FFE8">(const</span><span style="background-color: #E8FFE8"> path&amp; p, </span><span style="background-color: #E8FFE8">system::error_code</span><span style="background-color: #E8FFE8">&amp; </span><span style="background-color: #E8FFE8">ec</span><span style="background-color: #E8FFE8">);</span></pre>
<blockquote>
  <p><i>Returns:</i> <code>relative(p, current_path(), ec)</code>.</p>
  <p><i>Throws:</i>&nbsp; As specified in Error reporting.</p>
</blockquote>
<pre><span style="background-color: #E8FFE8">path </span><span style="background-color: #E8FFE8">relative(const</span><span style="background-color: #E8FFE8"> path&amp; p, const path&amp; base=</span><span style="background-color: #E8FFE8">current_path</span><span style="background-color: #E8FFE8">());</span>
<span style="background-color: #E8FFE8">path </span><span style="background-color: #E8FFE8">relative(const</span><span style="background-color: #E8FFE8"> path&amp; p, const path&amp; base, </span><span style="background-color: #E8FFE8">system::error_code</span><span style="background-color: #E8FFE8">&amp; </span><span style="background-color: #E8FFE8">ec</span><span style="background-color: #E8FFE8">);</span></pre>
<blockquote>
  <p><i>Overview:</i> Returns <code>p</code> made relative to <code>base</code>. 
  Treats empty or identical paths as corner cases, not errors. Resolves symlinks 
  and normalizes both <code>p</code> and <code>base</code> before other 
  processing.</p>
  <p><i>Returns:</i> <code><a href="#weakly_canonical">weakly_canonical</a>(p).<a href="#lex-relative">lexically_relative</a>(<a href="#weakly_canonical">weakly_canonical</a>(base))</code>. The second form returns <code>path()</code> 
  if an error occurs.</p>
  <p><i>Throws:</i> As specified in Error reporting.</p>
</blockquote>
<pre>bool <a name="remove">remove</a>(const path&amp; p);
bool <a name="remove2">remove</a>(const path&amp; p, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i>&nbsp; If <code>exists(symlink_status(p,ec))</code>, it is 
  removed 
  as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/remove.html">remove()</a></code>.</p>
  <blockquote>
  <p>[<i>Note:</i> A symbolic link is itself removed, rather than the file it 
  resolves to being removed. <i>—end note</i>]</p>
  </blockquote>
  <p><i>Postcondition:</i> <code>!exists(symlink_status(p))</code>.</p>
  <p><i>Returns:</i>&nbsp; <code>false</code> if p did not exist in the first 
  place, otherwise <code>true</code>.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre>uintmax_t <a name="remove_all">remove_all</a>(const path&amp; p);
uintmax_t <a name="remove_all2">remove_all</a>(const path&amp; p, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i>&nbsp; Recursively deletes the contents of p if it exists, 
  then deletes file <code>p</code> itself, 
  as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/remove.html">remove()</a></code>.</p>
  <blockquote>
  <p>[<i>Note:</i> A symbolic link is itself removed, rather than the file it 
  resolves to being removed. <i>—end note</i>]</p>
  </blockquote>
  <p><i>Postcondition:</i> <code>!exists(p)</code></p>
  <p><i>Returns:</i> The number of files removed.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre>void <a name="rename">rename</a>(const path&amp; old_p, const path&amp; new_p);
void <a name="rename2">rename</a>(const path&amp; old_p, const path&amp; new_p, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> Renames <code>old_p</code> to <code>new_p</code>, as if by
  ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/rename.html">rename()</a></code>.</p>
  <blockquote>
  <p>[<i>Note:</i> If <code>old_p</code> and <code>new_p</code> resolve to the 
  same existing file, no action is taken. Otherwise, if <code>new_p</code> resolves to an 
  existing non-directory file, it is removed, while if <code>new_p</code> resolves to an 
  existing directory, it is removed if empty on ISO/IEC 9945 but is an error on Windows. A symbolic link is itself renamed, rather than 
  the file it resolves to being renamed. <i>—end note</i>]</p>
  </blockquote>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre>void <a name="resize_file">resize_file</a>(const path&amp; p, uintmax_t new_size);
void <a name="resize_file2">resize_file</a>(const path&amp; p, uintmax_t new_size, system::error_code&amp; ec);</pre>
<blockquote>
<p><i>Postcondition:</i> <code>file_size() == new_size</code>.</p>
<p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p><i>Remarks:</i> Achieves its postconditions as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/truncate.html">truncate()</a></code>.</p>
</blockquote>
<pre>space_info <a name="space">space</a>(const path&amp; p);
space_info <a name="space2">space</a>(const path&amp; p, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Returns:</i> An object of type <code><a href="#space_info">space_info</a></code>. The value of the <code>space_info</code> object is determined as if by 
  using ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/statvfs.html"
   style="text-decoration: none">statvfs()</a></code> to obtain a ISO/IEC 9945 struct
  <code><a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/statvfs.h.html" style="text-decoration: none">statvfs</a></code>,
   and then multiplying its <code>f_blocks</code>, <code>f_bfree</code>,
   and <code>f_bavail</code> members by its <code>f_frsize</code> member,
   and assigning the results to the <code>capacity</code>, <code>free</code>, 
  and <code>available</code> members respectively. Any members for which the 
  value cannot be determined shall be set to -1.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
</blockquote>
<pre><a href="#file_status">file_status</a> <a name="status">status</a>(const path&amp; p);</pre>
<blockquote>
  <p><i>Effects: </i>As if:</p>
  <blockquote>
    <pre>system::error_code ec;
file_status result = status(p, ec);
if (result == status_error)
  throw filesystem_error(<i>implementation-supplied-message</i>, p, ec);
return result;</pre>
  </blockquote>
  <p><i>Returns:</i> See above.</p>
  <p><i>Throws:</i> <code>filesystem_error</code>. 
[<i>Note:</i> <code>result</code> values of <code>file_status(file_not_found)</code>and <code>file_status(type_unknown)</code> are not considered failures and do not 
  cause an exception to be 
thrown.<i> —end note</i>] </p>
  </blockquote>
<pre><a href="#file_status">file_status</a> <a name="status2">status</a>(const path&amp; p, system::error_code&amp; ec) noexcept;</pre>
<blockquote>
  <p><i>Effects: </i></p>
  <blockquote>
    <p>If possible, determines the attributes 
    of the file <code>p</code> resolves to, as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">stat()</a></code>.</p>
      If, during attribute determination, the underlying file system API reports 
    an error, sets <code>ec</code> to indicate the specific error reported. 
    Otherwise, <code>ec.clear()</code>.<blockquote>
      <p>[<i>Note:</i> This allows users to inspect the specifics of underlying 
      API errors even when the value returned by <code>status()</code> is not <code>file_status(status_error)</code>.&nbsp; <i>—end note</i>]</p>
    </blockquote>
    </blockquote>
  <p><i>Returns:</i></p>
  <blockquote>
    <p>If <code>ec != error_code()</code>:</p>
    <ul>
      <li>If the specific error indicates that <code>p</code> cannot be resolved 
      because some element of the path does not exist, return <code>
      file_status(file_not_found)</code>. [<i>Note:</i> ISO/IEC 9945 errors that 
      indicate this are ENOENT or ENOTDIR. Windows equivalents 
      include ERROR_FILE_NOT_FOUND, ERROR_PATH_NOT_FOUND, ERROR_INVALID_NAME, 
      ERROR_INVALID_PARAMETER, ERROR_BAD_PATHNAME, and ERROR_BAD_NETPATH. <i>-- 
      end note</i>]<br>
&nbsp;</li>
      <li>Otherwise, if the specific error indicates that <code>p</code> can be resolved 
      but the attributes cannot be determined, return <code>
      file_status(type_unknown)</code>. [<i>Note: </i>For example, Windows 
      ERROR_SHARING_VIOLATION errors. For ISO/IEC 9945, the case never arises. <i>—end 
      note</i>]<br>
&nbsp;</li>
      <li>Otherwise, return <code>
      file_status(status_error)</code>.</li>
    </ul>
        <blockquote>
        <p>[<i>Note:</i> These semantics distinguish between <code>p</code> being known not to exist, <code>p</code> existing but not being able to determine its attributes, 
        and there being an error that prevents even knowing if <code>p</code> exists. These 
        distinctions are important to some use cases.&nbsp;<i>—end note</i>]</p>
    </blockquote>
    <p>Otherwise,</p>
    <ul>
      <li>If the attributes indicate a regular file, as if by ISO/IEC 9945&nbsp;<a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISREG()</a>, 
      return <code>
      file_status(regular_file)</code>. [<i>Note:</i> <code>
regular_file</code> implies appropriate <code>&lt;fstream&gt;</code> operations 
      would succeed, assuming no hardware, permission, access, or file system 
      race 
      errors. Lack of
<code>regular_file</code> does not necessarily imply <code>&lt;fstream&gt;</code> operations would 
fail on a directory.
<i>—end note</i>]<br>
&nbsp;</li>
      <li>Otherwise, if the attributes indicate a directory, as if by ISO/IEC 9945
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISDIR()</a>, 
      return <code>
      file_status(directory_file)</code>. [<i>Note:</i> <code>directory_file</code> implies <code>
directory_iterator(p)</code>would succeed.
<i>—end note</i>]<br>
&nbsp;</li>
      <li>Otherwise, if the attributes indicate a block special file, as if by ISO/IEC 9945
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISBLK()</a>, 
      return <code>
      file_status(block_file)</code>.<br>
&nbsp;</li>
      <li>Otherwise, if the attributes indicate a character special file, as if by ISO/IEC 9945
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISCHR()</a>, 
      return <code>
      file_status(character_file)</code>.<br>
&nbsp;</li>
      <li>Otherwise, if the attributes indicate a fifo or pipe file, as if by
      ISO/IEC 9945
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISFIFO()</a>, 
      return <code>
      file_status(fifo_file)</code>.<br>
&nbsp;</li>
      <li>Otherwise, if the attributes indicate a socket, as if by ISO/IEC 
      9945
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISSOCK()</a>, 
      return <code>
      file_status(socket_file)</code>.<br>
&nbsp;</li>
      <li>Otherwise, return <code>
      file_status(type_unknown)</code>.</li>
    </ul>
    </blockquote>
      <p><i>Remarks:</i> If a symbolic link is encountered during pathname 
      resolution, 
      pathname resolution continues using the contents of the symbolic link.</p>
</blockquote>
<pre>bool <a name="status_known">status_known</a>(file_status s) noexcept;</pre>
<blockquote>
  <p><i>Returns:</i> <code>s.type() != status_error</code></p>
</blockquote>
<pre>file_status <a name="symlink_status">symlink_status</a>(const path&amp; p);
file_status <a name="symlink_status2">symlink_status</a>(const path&amp; p, system::error_code&amp; ec) noexcept;</pre>
<blockquote>
  <p><i>Effects:</i>&nbsp; Same as <a href="#status">status()</a>, above, 
  except that the attributes 
    of <code>p</code> are determined as if by ISO/IEC 9945 <code><a href="http://www.opengroup.org/onlinepubs/000095399/functions/lstat.html">lstat()</a></code>.</p>
</blockquote>
<blockquote>
      <p><i>Returns:</i> Same as <a href="#status">status()</a>, above, except 
      that if the attributes indicate a symbolic link, as if by ISO/IEC 9945 <a class="external" href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISLNK()</a>, return <code>file_status(symlink_file)</code>.</p>
      <p><i>Remarks:</i> Pathname resolution terminates if <code>p</code> names a symbolic link.</p>
  <p><i>Throws:</i> <code>filesystem_error</code>; overload with <code>error_code&amp;</code> throws 
  nothing.</p>
</blockquote>
<pre>path <a name="system_complete">system_complete</a>(const path&amp; p);
path <a name="system_complete2">system_complete</a>(const path&amp; p, system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Effects:</i> Composes an absolute path from <code>p</code>, using the 
  same rules used by the operating system to resolve a path passed as the 
  filename argument to standard library open functions.</p>
  <p><i>Returns:</i> The composed path.</p>
  <p><i>Postcondition:</i> For the returned path, <code>rp,</code> <code>rp.is_absolute()</code> is true.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p>[<i>Note:</i> For ISO/IEC 9945, <code>system_complete(p)</code> has the same semantics as <code>complete(p, current_path())</code>.</p>
  <p><a name="windows_effects">For <i>Windows</i></a>, <code>system_complete(p)</code> has the 
  same semantics as <code>complete(ph, current_path())</code> if <code>p.is_absolute() || !p.has_root_name()</code> or <code>p</code> and <code>base</code> have the same <code>root_name()</code>. 
  Otherwise it acts like <code>complete(p, kinky)</code>, where <code>kinky</code> is the current directory for the <code>p.root_name()</code> drive. This will 
  be the current directory of that drive the last time it was set, and thus may 
  be <b>residue left over from a prior program</b> run by the command 
  processor! Although these semantics are often useful, they are also very 
  error-prone.</p>
  <p>See <a href="#complete_note"><i>complete()</i> note</a> for usage suggestions. <i>—end note</i>]</p>
</blockquote>
<pre>path <a name="temp_directory_path">temp_directory_path</a>();
path temp_directory_path(system::error_code&amp; ec);</pre>
<blockquote>
  <p><i>Returns:</i> A directory path suitable for temporary files under the 
  conventions of the operating system. The specifics of how this path is 
  determined are implementation defined. An error shall be reported if<code> !exists(p) 
  || !is_directory(p)</code>, where <code>p</code> is the path to be returned.</p>
  <p>ISO/IEC 9945: The path supplied by the first environment variable found in the 
  list TMPDIR, TMP, TEMP, TEMPDIR. If none of these are found, <code>&quot;/tmp&quot;</code>, 
  or, if macro <code>__ANDROID__ </code>is defined, <code>&quot;/data/local/tmp&quot;</code>.</p>
  <p><i>Windows:</i> The path reported by the <i>Windows</i> <code>GetTempPath</code> API function.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p>[<i>Note: </i>The <code>temp_directory_path()</code> name was chosen to emphasize that the return is a 
  path, not just a single directory name.&nbsp; <i>—end note</i>]</p>
</blockquote>
<pre>path <a name="unique_path">unique_path</a>(const path&amp; model=&quot;%%%%-%%%%-%%%%-%%%%&quot;);
path unique_path(const path&amp; model, system::error_code&amp; ec);</pre>
<blockquote>
  <p>The <code>unique_path</code> function generates a path name suitable for 
  creating temporary files, including directories. The name is based 
  on a model that uses the percent sign character to specify replacement by a 
  random hexadecimal digit. [<i>Note:</i> The more bits of randomness in the 
  generated path name, the less likelihood of prior existence or being guessed. 
  Each replacement hexadecimal digit in the model adds four bits of randomness. 
  The default model thus provides 64 bits of randomness. This is sufficient for 
  most applications. <i>—end note</i>]</p>
  <p><i>Returns:</i> A path identical to <code>model</code>, except that each 
  occurrence of a percent sign character is replaced by a random hexadecimal 
  digit character in the range 0-9, a-f.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">Error reporting</a>.</p>
  <p><i>Remarks:</i> Implementations are encouraged to obtain the required 
  randomness via a <a href="http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator">cryptographically secure pseudo-random number generator</a>, such as one 
  provided by the operating system. [<i>Note</i>: Such generators may block 
  until sufficient entropy develops. <i>—end note</i>]</p>
</blockquote>
<pre><span style="background-color: #E8FFE8">path </span><a name="weakly_canonical"><span style="background-color: #E8FFE8">weakly_canonical</span></a><span style="background-color: #E8FFE8">(const</span><span style="background-color: #E8FFE8"> path&amp; p);</span>
<span style="background-color: #E8FFE8">path </span><span style="background-color: #E8FFE8">weakly_canonical(const</span><span style="background-color: #E8FFE8"> path&amp; p, </span><span style="background-color: #E8FFE8">system::error_code</span><span style="background-color: #E8FFE8">&amp; </span><span style="background-color: #E8FFE8">ec</span><span style="background-color: #E8FFE8">);</span></pre>
<blockquote>
  <p><i>Overview:</i> Returns <code>p</code> with symlinks resolved and the 
  result normalized.</p>
  <p><i>Returns: </i>A path composed of the result of calling the <code>
  canonical</code> function on a path composed of the leading elements of <code>
  p</code> that exist, if any, followed by the elements of <code>p</code> that 
  do not exist, if any.</p>
  <p><i>Postcondition:</i> The returned path is in
  <a href="#normal-form">
  normal form</a>.</p>
  <p><i>Remarks:</i> Uses <code>operator/=</code> to compose the returned path. 
  Uses the <code>status</code> function to determine existence.</p>
  <p><i>Remarks:</i> Implementations are encouraged to avoid unnecessary 
  normalization such as when <code>canonical</code> has already been called on 
  the entirety of <code>p</code>.</p>
  <p><i>Throws:</i>&nbsp; As specified in Error reporting.</p>
</blockquote>
<pre>&nbsp;</pre>
  <p>&nbsp;</p>
<hr>

<!-- generate-section-numbers=false -->


<h3><a name="File-streams">File streams</a> -
<a href="../../../boost/filesystem/fstream.hpp">&lt;boost/filesystem/fstream.hpp&gt;</a></h3>
<p>Replacements are provided for the file stream classes from the C++ standard 
library's <code>&lt;fstream&gt;</code> header. These replacement classes 
publicly inherit from the standard library classes. In the Boost.Filesystem 
version, constructors and open functions take <code>const path&amp;</code> arguments 
instead of <code>
const char*</code> arguments. There are no other differences in syntax or 
semantics.</p>
<pre>namespace boost
{
  namespace filesystem
  {
    template &lt; class charT, class traits = std::char_traits&lt;charT&gt; &gt;
    class basic_filebuf : public std::basic_filebuf&lt;charT,traits&gt;
    {
    public:
      basic_filebuf&lt;charT,traits&gt;*
        open(const path&amp; p, std::ios_base::openmode mode);
    };

    template &lt; class charT, class traits = std::char_traits&lt;charT&gt; &gt;
    class basic_ifstream : public std::basic_ifstream&lt;charT,traits&gt;
    {
    public:
      explicit basic_ifstream(const path&amp; p, std::ios_base::openmode mode=std::ios_base::in)
      void open(const path&amp; p, std::ios_base::openmode mode=std::ios_base::in);
    };

    template &lt; class charT, class traits = std::char_traits&lt;charT&gt; &gt;
    class basic_ofstream : public std::basic_ofstream&lt;charT,traits&gt;
    {
    public:
      explicit basic_ofstream(const path&amp; p, std::ios_base::openmode mode=std::ios_base::out);
      void open(const path&amp; p, std::ios_base::openmode mode=std::ios_base::out);
    };

    template &lt; class charT, class traits = std::char_traits&lt;charT&gt; &gt;
    class basic_fstream : public std::basic_fstream&lt;charT,traits&gt;
    {
    public:
      explicit basic_fstream(const path&amp; p,
        std::ios_base::openmode mode=std::ios_base::in | std::ios_base::out);
      void open(const path&amp; p,
        std::ios_base::openmode mode=std::ios_base::in | std::ios_base::out);
    };

    typedef basic_filebuf&lt;char&gt; filebuf;
    typedef basic_ifstream&lt;char&gt; ifstream;
    typedef basic_ofstream&lt;char&gt; ofstream;
    typedef basic_fstream&lt;char&gt; fstream;

    typedef basic_filebuf&lt;wchar_t&gt; wfilebuf;
    typedef basic_ifstream&lt;wchar_t&gt; wifstream;
    typedef basic_fstream&lt;wchar_t&gt; wfstream;
    typedef basic_ofstream&lt;wchar_t&gt; wofstream;
    
  }  // namespace filesystem
}  // namespace boost</pre>



<h2><a name="path-decomposition-table">Path decomposition table</a></h2>
<p>The table is generated by a program compiled with the Boost implementation.</p>
<p>Shaded entries indicate cases where ISO/IEC 9945 (POSIX) and Windows implementations yield different results. The top value is the
ISO/IEC 9945 result and the bottom value is the Windows result. <br>
<table border="1" cellspacing="0" cellpadding="5">
<p>
<tr><td><b>Constructor<br>argument</b></td>
<td><b>Iteration<br>over<br>Elements</b></td>
<td><b><code>string()</code></b></td>
<td><b><code>generic_<br>string()</code></b></td>
<td><b><code>root_<br>path()</code></b></td>
<td><b><code>root_<br>name()</code></b></td>
<td><b><code>root_<br>directory()</code></b></td>
<td><b><code>relative_<br>path()</code></b></td>
<td><b><code>parent_<br>path()</code></b></td>
<td><b><code>filename()</code></b></td>
</tr>
<tr>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
</tr>
<tr>
<td><code>.</code></td>
<td><code>.</code></td>
<td><code>.</code></td>
<td><code>.</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>.</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>..</code></td>
<td><code>..</code></td>
<td><code>..</code></td>
<td><code>..</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>..</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>..</code></td>
</tr>
<tr>
<td><code>foo</code></td>
<td><code>foo</code></td>
<td><code>foo</code></td>
<td><code>foo</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo</code></td>
</tr>
<tr>
<td><code>/</code></td>
<td><code>/</code></td>
<td><code>/</code></td>
<td><code>/</code></td>
<td><code>/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>/</code></td>
</tr>
<tr>
<td><code>/foo</code></td>
<td><code>/,foo</code></td>
<td><code>/foo</code></td>
<td><code>/foo</code></td>
<td><code>/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>/</code></td>
<td><code>foo</code></td>
<td><code>/</code></td>
<td><code>foo</code></td>
</tr>
<tr>
<td><code>foo/</code></td>
<td><code>foo,.</code></td>
<td><code>foo/</code></td>
<td><code>foo/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo/</code></td>
<td><code>foo</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>/foo/</code></td>
<td><code>/,foo,.</code></td>
<td><code>/foo/</code></td>
<td><code>/foo/</code></td>
<td><code>/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>/</code></td>
<td><code>foo/</code></td>
<td><code>/foo</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>foo/bar</code></td>
<td><code>foo,bar</code></td>
<td><code>foo/bar</code></td>
<td><code>foo/bar</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo/bar</code></td>
<td><code>foo</code></td>
<td><code>bar</code></td>
</tr>
<tr>
<td><code>/foo/bar</code></td>
<td><code>/,foo,bar</code></td>
<td><code>/foo/bar</code></td>
<td><code>/foo/bar</code></td>
<td><code>/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>/</code></td>
<td><code>foo/bar</code></td>
<td><code>/foo</code></td>
<td><code>bar</code></td>
</tr>
<tr>
<td><code>//net</code></td>
<td><code>//net</code></td>
<td><code>//net</code></td>
<td><code>//net</code></td>
<td><code>//net</code></td>
<td><code>//net</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>//net</code></td>
</tr>
<tr>
<td><code>//net/foo</code></td>
<td><code>//net,/,foo</code></td>
<td><code>//net/foo</code></td>
<td><code>//net/foo</code></td>
<td><code>//net/</code></td>
<td><code>//net</code></td>
<td><code>/</code></td>
<td><code>foo</code></td>
<td><code>//net/</code></td>
<td><code>foo</code></td>
</tr>
<tr>
<td><code>///foo///</code></td>
<td><code>/,foo,.</code></td>
<td><code>///foo///</code></td>
<td><code>///foo///</code></td>
<td><code>/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>/</code></td>
<td><code>foo///</code></td>
<td><code>///foo</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>///foo///bar</code></td>
<td><code>/,foo,bar</code></td>
<td><code>///foo///bar</code></td>
<td><code>///foo///bar</code></td>
<td><code>/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>/</code></td>
<td><code>foo///bar</code></td>
<td><code>///foo</code></td>
<td><code>bar</code></td>
</tr>
<tr>
<td><code>/.</code></td>
<td><code>/,.</code></td>
<td><code>/.</code></td>
<td><code>/.</code></td>
<td><code>/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>/</code></td>
<td><code>.</code></td>
<td><code>/</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>./</code></td>
<td><code>.,.</code></td>
<td><code>./</code></td>
<td><code>./</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>./</code></td>
<td><code>.</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>/..</code></td>
<td><code>/,..</code></td>
<td><code>/..</code></td>
<td><code>/..</code></td>
<td><code>/</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>/</code></td>
<td><code>..</code></td>
<td><code>/</code></td>
<td><code>..</code></td>
</tr>
<tr>
<td><code>../</code></td>
<td><code>..,.</code></td>
<td><code>../</code></td>
<td><code>../</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>../</code></td>
<td><code>..</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>foo/.</code></td>
<td><code>foo,.</code></td>
<td><code>foo/.</code></td>
<td><code>foo/.</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo/.</code></td>
<td><code>foo</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>foo/..</code></td>
<td><code>foo,..</code></td>
<td><code>foo/..</code></td>
<td><code>foo/..</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo/..</code></td>
<td><code>foo</code></td>
<td><code>..</code></td>
</tr>
<tr>
<td><code>foo/./</code></td>
<td><code>foo,.,.</code></td>
<td><code>foo/./</code></td>
<td><code>foo/./</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo/./</code></td>
<td><code>foo/.</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>foo/./bar</code></td>
<td><code>foo,.,bar</code></td>
<td><code>foo/./bar</code></td>
<td><code>foo/./bar</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo/./bar</code></td>
<td><code>foo/.</code></td>
<td><code>bar</code></td>
</tr>
<tr>
<td><code>foo/..</code></td>
<td><code>foo,..</code></td>
<td><code>foo/..</code></td>
<td><code>foo/..</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo/..</code></td>
<td><code>foo</code></td>
<td><code>..</code></td>
</tr>
<tr>
<td><code>foo/../</code></td>
<td><code>foo,..,.</code></td>
<td><code>foo/../</code></td>
<td><code>foo/../</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo/../</code></td>
<td><code>foo/..</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>foo/../bar</code></td>
<td><code>foo,..,bar</code></td>
<td><code>foo/../bar</code></td>
<td><code>foo/../bar</code></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>foo/../bar</code></td>
<td><code>foo/..</code></td>
<td><code>bar</code></td>
</tr>
<tr>
<td><code>c:</code></td>
<td><code>c:</code></td>
<td><code>c:</code></td>
<td><code>c:</code></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><font size="-1"><i>empty</i></font></td>
<td><span style="background-color: #CCFFCC"><code>c:</code><br><font size="-1"><i>empty</i></font></span></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>c:</code></td>
</tr>
<tr>
<td><code>c:/</code></td>
<td><span style="background-color: #CCFFCC"><code>c:,.</code><br><code>c:,/</code></span></td>
<td><code>c:/</code></td>
<td><code>c:/</code></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:/</code><br><font size="-1"><i>empty</i></font></span></td>
<td><code>c:</code></td>
<td><span style="background-color: #CCFFCC"><code>.</code><br><code>/</code></span></td>
</tr>
<tr>
<td><code>c:foo</code></td>
<td><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>c:,foo</code></span></td>
<td><code>c:foo</code></td>
<td><code>c:foo</code></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><font size="-1"><i>empty</i></font></td>
<td><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>foo</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>foo</code></span></td>
</tr>
<tr>
<td><code>c:/foo</code></td>
<td><span style="background-color: #CCFFCC"><code>c:,foo</code><br><code>c:,/,foo</code></span></td>
<td><code>c:/foo</code></td>
<td><code>c:/foo</code></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:/foo</code><br><code>foo</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:</code><br><code>c:/</code></span></td>
<td><code>foo</code></td>
</tr>
<tr>
<td><code>c:foo/</code></td>
<td><span style="background-color: #CCFFCC"><code>c:foo,.</code><br><code>c:,foo,.</code></span></td>
<td><code>c:foo/</code></td>
<td><code>c:foo/</code></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><font size="-1"><i>empty</i></font></td>
<td><span style="background-color: #CCFFCC"><code>c:foo/</code><br><code>foo/</code></span></td>
<td><code>c:foo</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>c:/foo/</code></td>
<td><span style="background-color: #CCFFCC"><code>c:,foo,.</code><br><code>c:,/,foo,.</code></span></td>
<td><code>c:/foo/</code></td>
<td><code>c:/foo/</code></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:/foo/</code><br><code>foo/</code></span></td>
<td><code>c:/foo</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>c:/foo/bar</code></td>
<td><span style="background-color: #CCFFCC"><code>c:,foo,bar</code><br><code>c:,/,foo,bar</code></span></td>
<td><code>c:/foo/bar</code></td>
<td><code>c:/foo/bar</code></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:/foo/bar</code><br><code>foo/bar</code></span></td>
<td><code>c:/foo</code></td>
<td><code>bar</code></td>
</tr>
<tr>
<td><code>prn:</code></td>
<td><code>prn:</code></td>
<td><code>prn:</code></td>
<td><code>prn:</code></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>prn:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>prn:</code></span></td>
<td><font size="-1"><i>empty</i></font></td>
<td><span style="background-color: #CCFFCC"><code>prn:</code><br><font size="-1"><i>empty</i></font></span></td>
<td><font size="-1"><i>empty</i></font></td>
<td><code>prn:</code></td>
</tr>
<tr>
<td><code>c:\</code></td>
<td><span style="background-color: #CCFFCC"><code>c:\</code><br><code>c:,/</code></span></td>
<td><code>c:\</code></td>
<td><span style="background-color: #CCFFCC"><code>c:\</code><br><code>c:/</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>\</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:\</code><br><font size="-1"><i>empty</i></font></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:\</code><br><code>\</code></span></td>
</tr>
<tr>
<td><code>c:foo</code></td>
<td><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>c:,foo</code></span></td>
<td><code>c:foo</code></td>
<td><code>c:foo</code></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><font size="-1"><i>empty</i></font></td>
<td><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>foo</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>foo</code></span></td>
</tr>
<tr>
<td><code>c:\foo</code></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo</code><br><code>c:,/,foo</code></span></td>
<td><code>c:\foo</code></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo</code><br><code>c:/foo</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>\</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo</code><br><code>foo</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo</code><br><code>foo</code></span></td>
</tr>
<tr>
<td><code>c:foo\</code></td>
<td><span style="background-color: #CCFFCC"><code>c:foo\</code><br><code>c:,foo,.</code></span></td>
<td><code>c:foo\</code></td>
<td><span style="background-color: #CCFFCC"><code>c:foo\</code><br><code>c:foo/</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><font size="-1"><i>empty</i></font></td>
<td><span style="background-color: #CCFFCC"><code>c:foo\</code><br><code>foo\</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:foo</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:foo\</code><br><code>.</code></span></td>
</tr>
<tr>
<td><code>c:\foo\</code></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo\</code><br><code>c:,/,foo,.</code></span></td>
<td><code>c:\foo\</code></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo\</code><br><code>c:/foo/</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>\</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo\</code><br><code>foo\</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\foo</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo\</code><br><code>.</code></span></td>
</tr>
<tr>
<td><code>c:\foo/</code></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo,.</code><br><code>c:,/,foo,.</code></span></td>
<td><code>c:\foo/</code></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo/</code><br><code>c:/foo/</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>\</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:\foo/</code><br><code>foo/</code></span></td>
<td><code>c:\foo</code></td>
<td><code>.</code></td>
</tr>
<tr>
<td><code>c:/foo\bar</code></td>
<td><span style="background-color: #CCFFCC"><code>c:,foo\bar</code><br><code>c:,/,foo,bar</code></span></td>
<td><code>c:/foo\bar</code></td>
<td><span style="background-color: #CCFFCC"><code>c:/foo\bar</code><br><code>c:/foo/bar</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:/foo\bar</code><br><code>foo\bar</code></span></td>
<td><span style="background-color: #CCFFCC"><code>c:</code><br><code>c:/foo</code></span></td>
<td><span style="background-color: #CCFFCC"><code>foo\bar</code><br><code>bar</code></span></td>
</tr>
</table>
<h2><a name="long-path-warning"></a>Warning: Long paths on Windows and the 
extended-length <b>\\?\ </b>prefix</h2>
<p>The Microsoft Windows &quot;Maximum Path Length Limitation&quot; specifies:</p>
<blockquote>
<p>In the Windows API (with some exceptions ...), the maximum length for a path 
is MAX_PATH, which is defined as 260 characters.</p>
<p>The Windows API has many functions that also have Unicode versions to permit 
an extended-length path for a maximum total path length of 32,767 characters. 
... To specify an extended-length path, use the <b>&quot;\\?\&quot; prefix</b>. For 
example, &quot;\\?\D:\<em>very long path</em>&quot;.&nbsp; <i>[C++ string literals require backslashes be doubled, of course.]</i></p>
</blockquote>
<p>Because most Boost.Filesystem operational functions just pass the contents of 
a class path object to the Windows API, they do work with the extended-length 
prefixes. But some won't work, because to the limitations imposed by Windows. 
Read the following cautions carefully!</p>
<h3>Cautions for paths with extended-length prefixes</h3>
<ul>
  <li>Individual components of a path are still are limited to whatever is 
  supported for the particular filesystem, commonly 255 characters.</li>
  <li>Only backslashes only are acceptable as directory separators. Slashes are 
  not treated as separators.</li>
  <li>All paths must be absolute - relative paths are not allowed.</li>
  <li>Once an absolute path grows beyond 260 characters, it is essentially 
  poisoned and all operations must use extended-length prefixes. So even a 
  simple operation like <code>create_directory(&quot;a&quot;)</code> will fail if the 
  absolute path of the resulting directory would exceed 260 characters.</li>
  <li>Certain Boost.Filesystem functions that decompose their argument path and 
  then work on individual relative directories or files will not work properly 
  with extended-length prefix paths.</li>
</ul>
<h2><a name="Acknowledgements">Acknowledgements</a></h2>
<p>This Filesystem Library is dedicated to my wife, Sonda, who provided the 
support necessary to see both a trial implementation and the proposal itself 
through to completion. She gave me the strength to continue after a difficult 
year of cancer treatment in the middle of it all.</p>
<p>Many people contributed technical comments, ideas, and suggestions to the 
Boost Filesystem Library. See <a href="http://www.boost.org/libs/filesystem/doc/index.htm#Acknowledgements">http://www.boost.org/libs/filesystem/doc/index.htm#Acknowledgements</a>.</p>
<p>Dietmar Kuehl contributed the original Boost Filesystem Library directory_iterator design. Peter Dimov, Walter Landry, Rob Stewart, and Thomas 
Witt were particularly helpful in refining the library.</p>
<p>The create_directories, extension, basename, and replace_extension functions 
were developed by Vladimir Prus. The temp_directory_path function was 
contributed by Jeff Flinn. David Svoboda suggested the canonical function and 
provided psuedo-code.</p>
<p>Howard Hinnant and John Maddock reviewed a draft of the version 2 proposal, and 
identified a number of mistakes or weaknesses, resulting in a more polished 
final document.</p>
<p>Peter Dimov suggested a single class path, with member templates to adapt to 
multiple string types. His idea became the basis for the version 3 path design.</p>
<h2><a name="References">References</a></h2>
<table border="0" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="100%">
  <tr>
    <td width="16%" valign="top">[<a name="ISO_POSIX">ISO/IEC 9945</a>]</td>
    <td width="84%">ISO/IEC 9945:2003, IEEE&nbsp;Std&nbsp;1003.1-2001, and The Open Group 
    Base Specifications, Issue 6. Also known as The Single Unix<font face="Times New Roman">&reg; 
    Specification, Version 3. Available from each of the organizations involved 
    in its creation. For example, read online or download from <a href="http://www.unix.org/single_unix_specification/">www.unix.org/single_unix_specification/</a>.</font> The ISO JTC1/SC22/WG15 - 
    POSIX homepage is <a href="http://www.open-std.org/jtc1/sc22/WG15/">www.open-std.org/jtc1/sc22/WG15/</a></td>
  </tr>
  <tr>
    <td width="16%" valign="top">[Abrahams]</td>
    <td width="84%">Dave Abrahams, Error and Exception Handling, <a href="http://www.boost.org/more/error_handling.html">www.boost.org/more/error_handling.html</a></td>
  </tr>
</table>
<hr>
<p><font size="2">&copy; Copyright Beman Dawes, 2002, 2006, 2007, 2009, 2010, 2011</font></p>
<p><font size="2">Distributed under the Boost Software License, Version 1.0. See
</font>
<a href="http://www.boost.org/LICENSE_1_0.txt"><font size="2">www.boost.org/LICENSE_1_0.txt</font></a></p>
<p><font size="2">Revised
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B %Y" startspan -->01 December 2015<!--webbot bot="Timestamp" endspan i-checksum="39286" --></font></p>


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