title: Php search string without allowing substrings
body: <p>I want to search this string:
  "This is, mybigstring"</p>
  
  <p>And search words could be:
  "is, big, mybigstring"</p>
  
  <p>At the moment I'm using stristr which will find matches for all these words. However I do not want "big" to match.. Meaning that I won't allow substrings. How can I do this?</p>
  
  <p>Update:
  I tried this out after reading your answers:</p>
  
  <pre><code>$testregxp = "\b(copenhagen|kobenhavn)\b";
  $test = "Copenhagen, Denmark";
  print preg_match($testregxp, strtolower($test));
  </code></pre>
  
  <p>But I can't seem to get it working..</p>