title: PHP Regular Expression. Check if String contains ONLY letters
body: <p>In PHP, how do I check if a String contains only letters?  I want to write an if statement that will return false if there is (white space, number, symbol) or anything else other than <code>a-z</code> and <code>A-Z</code>. </p>
  
  <p>My string must contain ONLY letters.</p>
  
  <p>I thought I could do it this way, but I'm doing it wrong:</p>
  
  <pre><code>if( ereg("[a-zA-Z]+", $myString))
     return true;
  else
     return false;
  </code></pre>
  
  <p>How do I find out if <code>myString</code> contains only letters?</p>