title: Regular Expression to Match String Exactly?
body: <p>I'll preface this question by mentioning that while I'm far from a regular expressions guru, they are not completely foreign to me. Building a regular expression to search for a pattern inside a particular string generally isn't a problem for me, but I have a (maybe?) unique situation.</p>
  
  <p>I have a set of values, say:</p>
  
  <blockquote>
    <p>028938<br>
    DEF567987<br>
    390987.456<br>
    GHI345928.039  </p>
  </blockquote>
  
  <p>I want to match a certain set of strings, such as:</p>
  
  <ul>
  <li>Strings composed of exactly 6 digits</li>
  <li>Strings composed of exactly 6 digits, a decimal, followed by exactly 3 more digits</li>
  </ul>
  
  <p>In the above examples, the first and third values should be matched.</p>
  
  <p>I'm using the regular expressions:</p>
  
  <pre><code>[0-9]{6}
  [0-9]{6}.[0-9]{3}
  </code></pre>
  
  <p>Unfortunately, since all the above examples <em>contain</em> the specified pattern, all values are matched. This is not my intention.</p>
  
  <p>So my question, in a nutshell, is how to write a regular expression that matches a string exactly and completely, with no additional characters to the right or left of the matched pattern? Is there a term for this type of matching? (Google was no help.) TIA</p>