title: Regex to match a string with 2 capital letters only
body: <p>I want to write a regex which will match a string only if the string consists of two capital letters.</p>
  
  <p>I tried - <code>[A-Z]{2}, [A-Z]{2, 2} and [A-Z][A-Z]</code> but these only match the string 'CAS' while I am looking to match only if the string is two capital letters like 'CA'.</p>