title: Get first 100 characters from string, respecting full words
body: <p>I have asked a similar question here before, but I need to know if this little tweak is possible.  I want to shorten a string to 100 characters and use <code>$small = substr($big, 0, 100);</code> to do so.  However, this just takes the first 100 characters and doesn't care whether it breaks up a word or not.</p>
  
  <p>Is there any way to take up to the first 100 characters of a string but make sure you don't break a word?</p>
  
  <p>Example:</p>
  
  <pre><code>$big = "This is a sentence that has more than 100 characters in it, and I want to return a string of only full words that is no more than 100 characters!"
  
  $small = some_function($big);
  
  echo $small;
  
  // OUTPUT: "This is a sentence that has more than 100 characters in it, and I want to return a string of only"
  </code></pre>
  
  <p>Is there a way to do this using PHP?</p>