text: /* $Id: stdio.h 517 2011-06-13 10:03:13Z solar $ */
  
  /* 7.19 Input/output <stdio.h>
  
     This file is part of the Public Domain C Library (PDCLib).
     Permission is granted to use, modify, and / or redistribute at will.
  */
  
  #ifndef _PDCLIB_STDIO_H
  #define _PDCLIB_STDIO_H _PDCLIB_STDIO_H
  
  #ifndef _PDCLIB_INT_H
  #define _PDCLIB_INT_H _PDCLIB_INT_H
  #include <_PDCLIB_int.h>
  #endif
  
  #ifndef _PDCLIB_SIZE_T_DEFINED
  #define _PDCLIB_SIZE_T_DEFINED _PDCLIB_SIZE_T_DEFINED
  typedef _PDCLIB_size_t size_t;
  #endif
  
  #ifndef _PDCLIB_NULL_DEFINED
  #define _PDCLIB_NULL_DEFINED _PDCLIB_NULL_DEFINED
  #define NULL _PDCLIB_NULL
  #endif
  
  /* See setvbuf(), third argument */
  #define _IOFBF 1
  #define _IOLBF 2
  #define _IONBF 4
  
  /* The following are platform-dependant, and defined in _PDCLIB_config.h. */
  typedef struct _PDCLIB_fpos_t fpos_t;
  typedef struct _PDCLIB_file_t FILE;
  #define EOF -1
  #define BUFSIZ _PDCLIB_BUFSIZ
  #define FOPEN_MAX _PDCLIB_FOPEN_MAX
  #define FILENAME_MAX _PDCLIB_FILENAME_MAX
  #define L_tmpnam _PDCLIB_L_tmpnam
  #define TMP_MAX _PDCLIB_TMP_MAX
  
  /* See fseek(), third argument */
  #define SEEK_CUR _PDCLIB_SEEK_CUR
  #define SEEK_END _PDCLIB_SEEK_END
  #define SEEK_SET _PDCLIB_SEEK_SET
  
  extern FILE * stdin;
  extern FILE * stdout;
  extern FILE * stderr;
  
  /* Operations on files */
  
  /* Remove the given file.
     Returns zero if successful, non-zero otherwise.
     This implementation does detect if a file of that name is currently open,
     and fails the remove in this case. This does not detect two distinct names
     that merely result in the same file (e.g. "/home/user/foo" vs. "~/foo").
  */
  int remove( const char * filename );
  
  /* Rename the given old file to the given new name.
     Returns zero if successful, non-zero otherwise. 
     This implementation does detect if the old filename corresponds to an open
     file, and fails the rename in this case.
     If there already is a file with the new filename, behaviour is defined by
     the glue code (see functions/_PDCLIB/rename.c).
  */
  int rename( const char * old, const char * new );
  
  /* Open a temporary file with mode "wb+", i.e. binary-update. Remove the file
     automatically if it is closed or the program exits normally (by returning
     from main() or calling exit()).
     Returns a pointer to a FILE handle for this file.
     This implementation does not remove temporary files if the process aborts
     abnormally (e.g. abort()).
  */
  FILE * tmpfile( void );
  
  /* Generate a file name that is not equal to any existing filename AT THE TIME
     OF GENERATION. Generate a different name each time it is called.
     Returns a pointer to an internal static buffer containing the filename if s
     is a NULL pointer. (This is not thread-safe!)
     Returns s if it is not a NULL pointer (s is then assumed to point to an array
     of at least L_tmpnam characters).
     Returns NULL if unable to generate a suitable name (because all possible
     names already exist, or the function has been called TMP_MAX times already).
     Note that this implementation cannot guarantee a file of the name generated
     is not generated between the call to this function and a subsequent fopen().
  */
  char * tmpnam( char * s );
  
  /* File access functions */
  
  /* Close the file associated with the given stream (after flushing its buffers).
     Returns zero if successful, EOF if any errors occur.
  */
  int fclose( FILE * stream );
  
  /* Flush the buffers of the given output stream. If the stream is an input
     stream, or an update stream with the last operation being an input operation,
     behaviour is undefined.
     If stream is a NULL pointer, perform the buffer flushing for all applicable
     streams.
     Returns zero if successful, EOF if a write error occurs.
     Sets the error indicator of the stream if a write error occurs.
  */
  int fflush( FILE * stream );
  
  /* Open the file with the given filename in the given mode, and return a stream
     handle for it in which error and end-of-file indicator are cleared. Defined
     values for mode are:
  
     READ MODES
                        text files        binary files
     without update     "r"               "rb"
     with update        "r+"              "rb+" or "r+b"
  
     Opening in read mode fails if no file with the given filename exists, or if
     cannot be read.
  
     WRITE MODES
                        text files        binary files
     without update     "w"               "wb"
     with update        "w+"              "wb+" or "w+b"
  
     With write modes, if a file with the given filename already exists, it is
     truncated to zero length.
  
     APPEND MODES
                        text files        binary files
     without update     "a"               "ab"
     with update        "a+"              "ab+" or "a+b"
  
     With update modes, if a file with the given filename already exists, it is
     not truncated to zero length, but all writes are forced to end-of-file (this
     regardless to fseek() calls). Note that binary files opened in append mode
     might have their end-of-file padded with '\0' characters.
  
     Update modes mean that both input and output functions can be performed on
     the stream, but output must be terminated with a call to either fflush(),
     fseek(), fsetpos(), or rewind() before input is performed, and input must
     be terminated with a call to either fseek(), fsetpos(), or rewind() before
     output is performed, unless input encountered end-of-file.
  
     If a text file is opened with update mode, the implementation is at liberty
     to open a binary stream instead. This implementation honors the exact mode
     given.
  
     The stream is fully buffered if and only if it can be determined not to
     refer to an interactive device.
  
     If the mode string begins with but is longer than one of the above sequences
     the implementation is at liberty to ignore the additional characters, or do
     implementation-defined things. This implementation only accepts the exact
     modes above.
  
     Returns a pointer to the stream handle if successfull, NULL otherwise.
  */
  FILE * fopen( const char * _PDCLIB_restrict filename, const char * _PDCLIB_restrict mode );
  
  /* Close any file currently associated with the given stream. Open the file
     identified by the given filename with the given mode (equivalent to fopen()),
     and associate it with the given stream. If filename is a NULL pointer,
     attempt to change the mode of the given stream.
     This implementation allows any mode changes on "real" files, and associating
     of the standard streams with files. It does *not* support mode changes on
     standard streams.
     (Primary use of this function is to redirect stdin, stdout, and stderr.)
  */
  FILE * freopen( const char * _PDCLIB_restrict filename, const char * _PDCLIB_restrict mode, FILE * _PDCLIB_restrict stream );
  
  /* If buf is a NULL pointer, call setvbuf( stream, NULL, _IONBF, BUFSIZ ).
     If buf is not a NULL pointer, call setvbuf( stream, buf, _IOFBF, BUFSIZ ).
  */
  void setbuf( FILE * _PDCLIB_restrict stream, char * _PDCLIB_restrict buf );
  
  /* Set the given stream to the given buffering mode. If buf is not a NULL
     pointer, use buf as file buffer (of given size). If buf is a NULL pointer,
     use a buffer of given size allocated internally. _IONBF causes unbuffered
     behaviour, _IOLBF causes line-buffered behaviour, _IOFBF causes fully
     buffered behaviour. Calling this function is only valid right after a file is
     opened, and before any other operation (except for any unsuccessful calls to
     setvbuf()) has been performed.
     Returns zero if successful, nonzero otherwise.
  */
  int setvbuf( FILE * _PDCLIB_restrict stream, char * _PDCLIB_restrict buf, int mode, size_t size );
  
  /* Formatted input/output functions */
  
  /*
     Write output to the given stream, as defined by the given format string and
     0..n subsequent arguments (the argument stack).
  
     The format string is written to the given stream verbatim, except for any
     conversion specifiers included, which start with the letter '%' and are
     documented below. If the given conversion specifiers require more arguments
     from the argument stack than provided, behaviour is undefined. Additional
     arguments not required by conversion specifiers are evaluated but otherwise
     ignored.
  
     (The standard specifies the format string is allowed to contain multibyte
     character sequences as long as it starts and ends in initial shift state,
     but this is not yet supported by this implementation, which interprets the
     format string as sequence of char.)
     TODO: Add multibyte support to printf() functions.
  
     A conversion specifier consists of:
     - Zero or more flags (one of the characters "-+ #0").
     - Optional minimum field width as decimal integer. Default is padding to the
       left, using spaces. Note that 0 is taken as a flag, not the beginning of a
       field width. Note also that a small field width will not result in the
       truncation of a value.
     - Optional precision (given as ".#" with # being a decimal integer),
       specifying:
       - the min. number of digits to appear (diouxX),
       - the max. number of digits after the decimal point (aAeEfF),
       - the max. number of significant digits (gG),
       - the max. number of bytes to be written (s).
       - behaviour with other conversion specifiers is undefined.
     - Optional length modifier specifying the size of the argument (one of "hh",
       "ll", or one of the characters "hljztL").
     - Conversion specifier character specifying the type of conversion to be
       applied (and the type of the next argument from the argument stack). One
       of the characters "diouxXfFeEgGaAcspn%".
  
     Minimum field width and/or precision may be given as asterisk ('*') instead
     of a decimal integer. In this case, the next argument from the argument
     stack is assumed to be an int value specifying the width / precision. A
     negative field width is interpreted as flag '-' followed by a positive field
     width. A negative precision is interpreted as if no precision was given.
  
     FLAGS
     -     Left-justify the conversion result within its field width.
     +     Prefix a '+' on positive signed conversion results. Prefix a '-' on
           floating conversions resulting in negative zero, or negative values
           rounding to zero.
     space Prefix a space on positive signed conversion results, or if a signed
           conversion results in no characters. If both '+' and ' ' are given,
           ' ' is ignored.
     #     Use an "alternative form" for
           - 'o' conversion, increasing precision until the first digit of the
             result is a zero;
           - 'x' or 'X' conversion, prefixing "0x" or "0X" to nonzero results;
           - "aAeEfF" conversions, always printing a decimal point even if no
             digits are following;
           - 'g' or 'G' conversions, always printing a decimal point even if no
             digits are following, and not removing trailing zeroes.
           - behaviour for other conversions is unspecified.
     0     Use leading zeroes instead of spaces for field width padding. If both
           '-' and '0' are given, '0' is ignored. If a precision is specified for
           any of the "diouxX" conversions, '0' is ignored. Behaviour is only
           defined for "diouxXaAeEfFgG".
  
     LENGTH MODIFIERS
     hh  For "diouxX" conversions, the argument from the argument stack is
         assumed to be of char width. (It will have been subject to integer
         promotion but will be converted back.) For 'n' conversions, the argument
         is assumed to be a pointer to signed char.
     h   For "diouxX" conversions, the argument from the argument stack is
         assumed to be of short int width. (It will have been subject to integer
         promotion but will be converted back.) For 'n' conversions, the argument
         is assumed to be a pointer to short int.
     l   For "diouxX" conversions, the argument from the argument stack is
         assumed to be of long int width. For 'n' conversions, the argument is
         assumed to be a pointer to short int. For 'c' conversions, the argument
         is assumed to be a wint_t. For 's' conversions, the argument is assumed
         to be a pointer to wchar_t. No effect on "aAeEfFgG" conversions.
     ll  For "diouxX" conversions, the argument from the argument stack is
         assumed to be of long long int width. For 'n' conversions, the argument
         is assumed to be a pointer to long long int.
     j   For "diouxX" conversions, the argument from the argument stack is
         assumed to be of intmax_t width. For 'n' conversions, the argument is
         assumed to be a pointer to intmax_t.
     z   For "diouxX" conversions, the argument from the argument stack is
         assumed to be of size_t width. For 'n' conversions, the argument is
         assumed to be a pointer to size_t.
     t   For "diouxX" conversions, the argument from the argument stack is
         assumed to be of ptrdiff_t width. For 'n' conversions, the argument is
         assumed to be a pointer to ptrdiff_t.
     L   For "aAeEfFgG" conversions, the argument from the argument stack is
         assumed to be a long double.
     Length modifiers appearing for any conversions not mentioned above will have
     undefined behaviour.
     If a length modifier appears with any conversion specifier other than as
     specified above, the behavior is undefined.
  
     CONVERSION SPECIFIERS
     d,i The argument from the argument stack is assumed to be of type int, and
         is converted to a signed decimal value with a minimum number of digits
         as specified by the precision (default 1), padded with leading zeroes.
         A zero value converted with precision zero yields no output.
     o   The argument from the argument stack is assumed to be of type unsigned
         int, and is converted to an unsigned octal value, other behaviour being
         as above.
     u   The argument from the argument stack is assumed to be of type unsigned
         int, and converted to an unsigned decimal value, other behaviour being
         as above.
     x,X The argument from the argument stack is assumed to be of type unsigned
         int, and converted to an unsigned hexadecimal value, using lowercase
         "abcdef" for 'x' and uppercase "ABCDEF" for 'X' conversion, other
         behaviour being as above.
     f,F The argument from the argument stack is assumed to be of type double,
         and converted to a decimal floating point in decimal-point notation,
         with the number of digits after the decimal point as specified by the
         precision (default 6) and the value being rounded appropriately. If
         precision is zero (and the '#' flag is not given), no decimal point is
         printed. At least one digit is always printed before the decimal point.
         For 'f' conversions, an infinity value is printed as either [-]inf or
         [-]infinity (, depending on the configuration of this implementation. A
         NaN value is printed as [-]nan. For 'F' conversions uppercase characters
         are used for these special values. The flags '-', '+' and ' ' apply as
         usual to these special values, '#' and '0' have no effect.
     e,E The argument from the argument stack is assumed to be of type double,
         and converted to a decimal floating point in normalized exponential
         notation ([?]d.ddd edd). "Normalized" means one nonzero digit before
         the decimal point, unless the value is zero. The number of digits after
         the decimal point is specified by the precision (default 6), the value
         being rounded appropriately. If precision is zero (and the '#' flag is
         not given), no decimal point is printed. The exponent has at least two
         digits, and not more than necessary to represent the exponent. If the
         value is zero, the exponent is zero. The 'e' written to indicate the
         exponend is uppercase for 'E' conversions.
         Infinity or NaN values are represented as for 'f' and 'F' conversions,
         respectively.
     g,G The argument from the argument stack is assumed to be of type double,
         and converted according to either 'f' or 'e' format for 'g' conversions,
         or 'F' or 'E' format for 'G' conversions, respectively, with the actual
         conversion chosen depending on the value. 'e' / 'E' conversion is chosen
         if the resulting exponent is < -4 or >= the precision (default 1).
         Trailing zeroes are removed (unless the '#' flag is given). A decimal
         point appears only if followed by a digit.
         Infinity or NaN values are represented as for 'f' and 'F' conversions,
         respectively.
     a,A The argument from the argument stack is assumed to be of type double,
         and converted to a floating point hexadecimal notation ([?]0xh.hhhh pd)
         with one hexadecimal digit (being nonzero if the value is normalized,
         and otherwise unspecified) before the decimal point, and the number of
         digits after the decimal point being specified by the precision. If no
         precision is given, the default is to print as many digits as nevessary
         to give an exact representation of the value (if FLT_RADIX is a power of
         2). If no precision is given and FLT_RADIX is not a power of 2, the
         default is to print as many digits to distinguish values of type double
         (possibly omitting trailing zeroes). (A precision p is sufficient to
         distinguish values of the source type if 16^p-1 > b^n where b is
         FLT_RADIX and n is the number of digits in the significand (to base b)
         of the source type. A smaller p might suffice depending on the
         implementation's scheme for determining the digit to the left of the
         decimal point.) The error has the correct sign for the current rounding
         direction.
         Unless the '#' flag is given, no decimal-point is given for zero
         precision.
         The 'a' conversion uses lowercase "abcdef", "0x" and 'p', the 'A'
         conversion uppercase "ABCDEF", "0X" and 'P'.
         The exponent always has at least one digit, and not more than necessary
         to represent the decimal exponent of 2. If the value is zero, the
         exponent is zero.
         Infinity or NaN values are represented as for 'f' and 'F' conversions,
         respectively.
         Binary implementations are at liberty to chose the hexadecimal digit to
         the left of the decimal point so that subsequent digits align to nibble
         boundaries.
     c   The argument from the argument stack is assumed to be of type int, and
         converted to a character after the value has been cast to unsigned char.
         If the 'l' length modifier is given, the argument is assumed to be of
         type wint_t, and converted as by a "%ls" conversion with no precision
         and a pointer to a two-element wchar_t array, with the first element
         being the wint_t argument and the second a '\0' wide character.
     s   The argument from the argument stack is assumed to be a char array (i.e.
         pointer to char). Characters from that array are printed until a zero
         byte is encountered or as many bytes as specified by a given precision
         have been written.
         If the l length modifier is given, the argument from the argument stack
         is assumed to be a wchar_t array (i.e. pointer to wchar_t). Wide
         characters from that array are converted to multibyte characters as by
         calls to wcrtomb() (using a mbstate_t object initialized to zero prior
         to the first conversion), up to and including the terminating null wide
         character. The resulting multibyte character sequence is then printed up
         to but not including the terminating null character. If a precision is
         given, it specifies the maximum number of bytes to be written (including
         shift sequences). If the given precision would require access to a wide
         character one past the end of the array, the array shall contain a '\0'
         wide character. In no case is a partial multibyte character written.
         Redundant shift sequences may result if the multibyte characters have a
         state-dependent encoding.
         TODO: Clarify these statements regarding %ls.
     p   The argument from the argument stack is assumed to be a void pointer,
         and converted to a sequence of printing characters in an implementation-
         defined manner.
         This implementation casts the pointer to type intptr_t, and prints the
         value as if a %#x conversion specifier was given.
     n   The argument from the argument stack is assumed to be a pointer to a
         signed integer, into which the number of characters written so far by
         this call to fprintf is stored. The behaviour, should any flags, field
         widths, or precisions be given is undefined.
     %   A verbatim '%' character is written. No argument is taken from the
         argument stack.
  
     Returns the number of characters written if successful, a negative value
     otherwise.
  */
  int fprintf( FILE * _PDCLIB_restrict stream, const char * _PDCLIB_restrict format, ... );
  
  /* TODO: fscanf() documentation */
  /*
     Read input from a given stream, as defined by the given format string, and
     store converted input in the objects pointed to by 0..n subsequent arguments
     (the argument stack).
  
     The format string contains a sequence of directives that are expected to
     match the input. If such a directive fails to match, the function returns
     (matching error). It also returns if an input error occurs (input error).
  
     Directives can be:
     - one or more whitespaces, matching any number of whitespaces in the input;
     - printing characters, matching the input verbatim;
     - conversion specifications, which convert an input sequence into a value as
       defined by the individual specifier, and store that value in a memory
       location pointed to by the next pointer on the argument stack. Details are
       documented below. If there is an insufficient number of pointers on the
       argument stack, behaviour is undefined. Additional arguments not required
       by any conversion specifications are evaluated, but otherwise ignored.
  
     (The standard specifies the format string is allowed to contain multibyte
     character sequences as long as it starts and ends in initial shift state,
     but this is not yet supported by this implementation, which interprets the
     format string as sequence of char.)
     TODO: Add multibyte support to scanf() functions.
  
     A conversion specifier consists of:
     - Optional assignment-suppressing character ('*') that makes the conversion
       read input as usual, but does not assign the conversion result.
     - Optional maximum field width as decimal integer.
     - Optional length modifier specifying the size of the argument (one of "hh",
       "ll", or one of the characters "hljztL").
     - Conversion specifier character specifying the type of conversion to be
       applied (and the type of the next argument from the argument stack). One
       of the characters "diouxXaAeEfFgGcs[pn%".
  
     LENGTH MODIFIERS
     hh  For "diouxXn" conversions, the next pointer from the argument stack is
         assumed to point to a variable of of char width.
     h   For "diouxXn" conversions, the next pointer from the argument stack is
         assumed to point to a variable of short int width.
     l   For "diouxXn" conversions, the next pointer from the argument stack is
         assumed to point to a variable of long int width.
         For "aAeEfFgG" conversions, it is assumed to point to a variable of type
         double.
         For "cs[" conversions, it is assumed to point to a variable of type
         wchar_t.
     ll  For "diouxXn" conversions, the next pointer from the argument stack is
         assumed to point to a variable of long long int width.
     j   For "diouxXn" conversions, the next pointer from the argument stack is
         assumed to point to a variable of intmax_t width.
     z   For "diouxXn" conversions, the next pointer from the argument stack is
         assumed to point to a variable of size_t width.
     t   For "diouxXn" conversions, the next pointer from the argument stack is
         assumed to point to a variable of ptrdiff_t width.
     L   For "aAeEfFgG" conversions, the next pointer from the argument stack is
         assumed to point to a variable of type long double.
     Length modifiers appearing for any conversions not mentioned above will have
     undefined behaviour.
     If a length modifier appears with any conversion specifier other than as
     specified above, the behavior is undefined.
  
     CONVERSION SPECIFIERS
     d    Matches an (optionally signed) decimal integer of the format expected
          by strtol() with base 10. The next pointer from the argument stack is
          assumed to point to a signed integer.
     i    Matches an (optionally signed) integer of the format expected by
          strtol() with base 0. The next pointer from the argument stack is
          assumed to point to a signed integer.
     o    Matches an (optionally signed) octal integer of the format expected by
          strtoul() with base 8. The next pointer from the argument stack is
          assumed to point to an unsigned integer.
     u    Matches an (optionally signed) decimal integer of the format expected
          by strtoul() with base 10. The next pointer from the argument stack is
          assumed to point to an unsigned integer.
     x    Matches an (optionally signed) hexadecimal integer of the format
          expected by strtoul() with base 16. The next pointer from the argument
          stack is assumed to point to an unsigned integer.
     aefg Matches an (optionally signed) floating point number, infinity, or not-
          a-number-value of the format expected by strtod(). The next pointer
          from the argument stack is assumed to point to a float.
     c    Matches a number of characters as specified by the field width (default
          1). The next pointer from the argument stack is assumed to point to a
          character array large enough to hold that many characters.
          If the 'l' length modifier is given, the input is assumed to match a
          sequence of multibyte characters (starting in the initial shift state),
          which will be converted to a wide character sequence as by successive
          calls to mbrtowc() with a mbstate_t object initialized to zero prior to
          the first conversion. The next pointer from the argument stack is
          assumed to point to a wchar_t array large enough to hold that many
          characters.
          In either case, note that no '\0' character is added to terminate the
          sequence.
     s    Matches a sequence of non-white-space characters. The next pointer from
          the argument stack is assumed to point to a character array large
          enough to hold the sequence including terminating '\0' character.
          If the 'l' length modifier is given, the input is assumed to match a
          sequence of multibyte characters (starting in the initial shift state),
          which will be converted to a wide character sequence as by a call to
          mbrtowc() with a mbstate_t object initialized to zero prior to the
          first conversion. The next pointer from the argument stack is assumed
          to point to a wchar_t array large enough to hold the sequence including
          terminating '\0' character.
     [    Matches a nonempty sequence consisting of any of those characters
          specified between itself and a corresponding closing bracket (']').
          If the first character in the list is a circumflex ('^'), this matches
          a nonempty sequence consisting of any characters NOT specified. If the
          closing bracket appears as the first character in the scanset ("[]" or
          "[^]", it is assumed to belong to the scanset, which then ends with the
          NEXT closing bracket.
          If there is a '-' character in the scanset which is not the first after
          the opening bracket (or the circumflex, see above) or the last in the
          scanset, behaviour is implementation-defined. This implementation
          handles this character like any other.
  
          The extend of the input field is determined byte-by-byte for the above
          conversions ('c', 's', '['), with no special provisions being made for
          multibyte characters. The resulting field is nevertheless a multibyte
          sequence begining in intial shift state.
  
     p    Matches a sequence of characters as produced by the printf() "%p"
          conversion. The next pointer from the argument stack is assumed to
          point to a void pointer, which will be filled with the same location
          as the pointer used in the printf() statement. Note that behaviour is
          undefined if the input value is not the result of an earlier printf()
          call.
     n    Does not read input. The next pointer from the argument stack is
          assumed to point to a signed integer, into which the number of
          characters read from input so far by this call to fscanf() is stored.
          This does not affect the return value of fscanf(). The behaviour,
          should an assignment-supressing character of field width be given,
          is undefined.
          This can be used to test the success of literal matches and suppressed
          assignments.
     %    Matches a single, verbatim '%' character.
  
     A, E, F, G and X are valid, and equivalent to their lowercase counterparts.
  
     All conversions except [, c, or n imply that whitespace characters from the
     input stream are consumed until a non-whitespace character is encountered.
     Such whitespaces do not count against a maximum field width.
  
     Conversions push at most one character back into the input stream. That
     implies that some character sequences converted by the strtol() and strtod()
     function families are not converted identically by the scnaf() function
     family.
  
     Returns the number of input items successfully assigned. This can be zero if
     an early mismatch occurs. Returns EOF if an input failure occurs before the
     first conversion.
  */
  int fscanf( FILE * _PDCLIB_restrict stream, const char * _PDCLIB_restrict format, ... );
  
  /* Equivalent to fprintf( stdout, format, ... ). */
  int printf( const char * _PDCLIB_restrict format, ... );
  
  /* Equivalent to fscanf( stdin, format, ... ). */
  int scanf( const char * _PDCLIB_restrict format, ... );
  
  /* Equivalent to fprintf( stdout, format, ... ), except that the result is
     written into the buffer pointed to by s, instead of stdout, and that any
     characters beyond the (n-1)th are discarded. The (n)th character is
     replaced by a '\0' character in this case.
     Returns the number of characters that would have been written (not counting
     the terminating '\0' character) if n had been sufficiently large, if
     successful, and a negative number if an encoding error ocurred.
  */
  int snprintf( char * _PDCLIB_restrict s, size_t n, const char * _PDCLIB_restrict format, ... );
  
  /* Equivalent to fprintf( stdout, format, ... ), except that the result is
     written into the buffer pointed to by s, instead of stdout.
  */
  int sprintf( char * _PDCLIB_restrict s, const char * _PDCLIB_restrict format, ... );
  
  /* Equivalent to fscanf( stdin, format, ... ), except that the input is read
     from the buffer pointed to by s, instead of stdin.
  */
  int sscanf( const char * _PDCLIB_restrict s, const char * _PDCLIB_restrict format, ... );
  
  /* Equivalent to fprintf( stream, format, ... ), except that the argument stack
     is passed as va_list parameter. Note that va_list is not declared by
     <stdio.h>.
  */
  int vfprintf( FILE * _PDCLIB_restrict stream, const char * _PDCLIB_restrict format, _PDCLIB_va_list arg );
  
  /* Equivalent to fscanf( stream, format, ... ), except that the argument stack
     is passed as va_list parameter. Note that va_list is not declared by
     <stdio.h>.
  */
  int vfscanf( FILE * _PDCLIB_restrict stream, const char * _PDCLIB_restrict format, _PDCLIB_va_list arg );
  
  /* Equivalent to fprintf( stdout, format, ... ), except that the argument stack
     is passed as va_list parameter. Note that va_list is not declared by
     <stdio.h>.
  */
  int vprintf( const char * _PDCLIB_restrict format, _PDCLIB_va_list arg );
  
  /* Equivalent to fscanf( stdin, format, ... ), except that the argument stack
     is passed as va_list parameter. Note that va_list is not declared by
     <stdio.h>.
  */
  int vscanf( const char * _PDCLIB_restrict format, _PDCLIB_va_list arg );
  
  /* Equivalent to snprintf( s, n, format, ... ), except that the argument stack
     is passed as va_list parameter. Note that va_list is not declared by
     <stdio.h>.
     */
  int vsnprintf( char * _PDCLIB_restrict s, size_t n, const char * _PDCLIB_restrict format, _PDCLIB_va_list arg );
  
  /* Equivalent to fprintf( stdout, format, ... ), except that the argument stack
     is passed as va_list parameter, and the result is written to the buffer
     pointed to by s, instead of stdout. Note that va_list is not declared by
     <stdio.h>.
  */
  int vsprintf( char * _PDCLIB_restrict s, const char * _PDCLIB_restrict format, _PDCLIB_va_list arg );
  
  /* Equivalent to fscanf( stdin, format, ... ), except that the argument stack
     is passed as va_list parameter, and the input is read from the buffer
     pointed to by s, instead of stdin. Note that va_list is not declared by
     <stdio.h>.
  */
  int vsscanf( const char * _PDCLIB_restrict s, const char * _PDCLIB_restrict format, _PDCLIB_va_list arg );
  
  /* Character input/output functions */
  
  /* Retrieve the next character from given stream.
     Returns the character, EOF otherwise.
     If end-of-file is reached, the EOF indicator of the stream is set.
     If a read error occurs, the error indicator of the stream is set.
  */
  int fgetc( FILE * stream );
  
  /* Read at most n-1 characters from given stream into the array s, stopping at
     \n or EOF. Terminate the read string with \n. If EOF is encountered before
     any characters are read, leave the contents of s unchanged.
     Returns s if successful, NULL otherwise.
     If a read error occurs, the error indicator of the stream is set. In this
     case, the contents of s are indeterminate.
  */
  char * fgets( char * _PDCLIB_restrict s, int n, FILE * _PDCLIB_restrict stream );
  
  /* Write the value c (cast to unsigned char) to the given stream.
     Returns c if successful, EOF otherwise.
     If a write error occurs, sets the error indicator of the stream is set.
  */
  int fputc( int c, FILE * stream );
  
  /* Write the string s (not including the terminating \0) to the given stream.
     Returns a value >=0 if successful, EOF otherwise.
     This implementation does set the error indicator of the stream if a write
     error occurs.
  */
  int fputs( const char * _PDCLIB_restrict s, FILE * _PDCLIB_restrict stream );
  
  /* Equivalent to fgetc( stream ), but may be overloaded by a macro that
     evaluates its parameter more than once.
  */
  int getc( FILE * stream );
  
  /* Equivalent to fgetc( stdin ). */
  int getchar( void );
  
  /* Read characters from given stream into the array s, stopping at \n or EOF.
     The string read is terminated with \0. Returns s if successful. If EOF is
     encountered before any characters are read, the contents of s are unchanged,
     and NULL is returned. If a read error occurs, the contents of s are indeter-
     minate, and NULL is returned.
  */
  char * gets( char * s );
  
  /* Equivalent to fputc( c, stream ), but may be overloaded by a macro that
     evaluates its parameter more than once.
  */
  int putc( int c, FILE * stream );
  
  /* Equivalent to fputc( c, stdout ), but may be overloaded by a macro that
     evaluates its parameter more than once.
  */
  int putchar( int c );
  
  /* Write the string s (not including the terminating \0) to stdout, and append
     a newline to the output. Returns a value >= 0 when successful, EOF if a
     write error occurred.
  */
  int puts( const char * s );
  
  /* Push the value c (cast to unsigned char) back onto the given (input) stream.
     A character pushed back in this way will be delivered by subsequent read
     operations (and skipped by subsequent file positioning operations) as if it
     has not been read. The external representation of the stream is unaffected
     by this pushback (it is a buffer operation). One character of pushback is
     guaranteed, further pushbacks may fail. EOF as value for c does not change
     the input stream and results in failure of the function.
     For text files, the file position indicator is indeterminate until all
     pushed-back characters are read. For binary files, the file position
     indicator is decremented by each successful call of ungetc(). If the file
     position indicator for a binary file was zero before the call of ungetc(),
     behaviour is undefined. (Older versions of the library allowed such a call.)
     Returns the pushed-back character if successful, EOF if it fails.
  */
  int ungetc( int c, FILE * stream );
  
  /* Direct input/output functions */
  
  /* Read up to nmemb elements of given size from given stream into the buffer
     pointed to by ptr. Returns the number of elements successfully read, which
     may be less than nmemb if a read error or EOF is encountered. If a read
     error is encountered, the value of the file position indicator is
     indeterminate. If a partial element is read, its value is indeterminate.
     If size or nmemb are zero, the function does nothing and returns zero.
  */
  size_t fread( void * _PDCLIB_restrict ptr, size_t size, size_t nmemb, FILE * _PDCLIB_restrict stream );
  
  /* Write up to nmemb elements of given size from buffer pointed to by ptr to
     the given stream. Returns the number of elements successfully written, which
     will be less than nmemb only if a write error is encountered. If a write
     error is encountered, the value of the file position indicator is
     indeterminate. If size or nmemb are zero, the function does nothing and
     returns zero.
  */
  size_t fwrite( const void * _PDCLIB_restrict ptr, size_t size, size_t nmemb, FILE * _PDCLIB_restrict stream );
  
  /* File positioning functions */
  
  /* Store the current position indicator (and, where appropriate, the current
     mbstate_t status object) for the given stream into the given pos object. The
     actual contents of the object are unspecified, but it can be used as second
     parameter to fsetpos() to reposition the stream to the exact position and
     parse state at the time fgetpos() was called.
     Returns zero if successful, nonzero otherwise.
     TODO: Implementation-defined errno setting for fgetpos().
  */
  int fgetpos( FILE * _PDCLIB_restrict stream, fpos_t * _PDCLIB_restrict pos );
  
  /* Set the position indicator for the given stream to the given offset from:
     - the beginning of the file if whence is SEEK_SET,
     - the current value of the position indicator if whence is SEEK_CUR,
     - end-of-file if whence is SEEK_END.
     On text streams, non-zero offsets are only allowed with SEEK_SET, and must
     have been returned by ftell() for the same file.
     Any characters buffered by ungetc() are dropped, the end-of-file indicator
     for the stream is cleared. If the given stream is an update stream, the next
     operation after a successful fseek() may be either input or output.
     Returns zero if successful, nonzero otherwise. If a read/write error occurs,
     the error indicator for the given stream is set.
  */
  int fseek( FILE * stream, long int offset, int whence );
  
  /* Set the position indicator (and, where appropriate the mbstate_t status
     object) for the given stream to the given pos object (created by an earlier
     call to fgetpos() on the same file).
     Any characters buffered by ungetc() are dropped, the end-of-file indicator
     for the stream is cleared. If the given stream is an update stream, the next
     operation after a successful fsetpos() may be either input or output.
     Returns zero if successful, nonzero otherwise. If a read/write error occurs,
     the error indicator for the given stream is set.
     TODO: Implementation-defined errno setting for fsetpos().
  */
  int fsetpos( FILE * stream, const fpos_t * pos );
  
  /* Return the current offset of the given stream from the beginning of the
     associated file. For text streams, the exact value returned is unspecified
     (and may not be equal to the number of characters), but may be used in
     subsequent calls to fseek().
     Returns -1L if unsuccessful.
     TODO: Implementation-defined errno setting for ftell().
  */
  long int ftell( FILE * stream );
  
  /* Equivalent to (void)fseek( stream, 0L, SEEK_SET ), except that the error
     indicator for the stream is also cleared.
  */
  void rewind( FILE * stream );
  
  /* Error-handling functions */
  
  /* Clear the end-of-file and error indicators for the given stream. */
  void clearerr( FILE * stream );
  
  /* Return zero if the end-of-file indicator for the given stream is not set,
     nonzero otherwise.
  */
  int feof( FILE * stream );
  
  /* Return zero if the error indicator for the given stream is not set, nonzero
     otherwise.
  */
  int ferror( FILE * stream );
  
  /* If s is neither a NULL pointer nor an empty string, print the string to
     stderr (with appended colon (':') and a space) first. In any case, print an
     error message depending on the current value of errno (being the same as if
     strerror( errno ) had been called).
  */
  void perror( const char * s );
  
  #endif
  