title: PCRE Regular Expression with NOT Operation
body: <p>Is it possible to use something equivalent to a NOT operation in a regular expression so as to match the string only if it does NOT contain a certain character in a given position?</p>
  
  <p>I see the meta characters say ^ can mean "negate a class" but I am having trouble finding examples of its use.  And that particular character is ambiguous with the start of a string so its a bit confusing as well.</p>