title: Check if the string does not contain any alphabetic characters in PHP?
body: <p>Is there a way to find out whether the string does not contain any alphabetic characters?</p>
  
  <p>I am thinking of doing a regular expression match. But struggling to do it.</p>
  
  <p>Basically I want to replace "string which does not contain any alphabetic character" to null.</p>
  
  <p>Hope I am clear with my question. Any help would be appreciated.</p>