Regular Expressions

Negation and Predefined Character Classes

• You can specify a negated collection of values by making the first character after the "[" character a "^" character.
• Example:
  

  $theVar = "This is a test";
  if ($theVar =~ /is [^a] tes/) {
      (print "Match One\n");  # Would Not Match
  }
  if ($theVar =~ /is [^A] tes/) {
      (print "Match Two\n");  # Would Match
  }
  

• For simplicity, a collection of predefined patterns exist with the following shorthand:

Character Class Matching Shorthand

Construct Symbol	Meaning	Same As
\d	Digit Character	[0-9]
\w	Word Character	[a-zA-Z0-9_]
\s	Space Character	[ \r\t\n\f]
\D	Not Digit Character	[^0-9]
\W	Not Word Character	[^a-zA-Z0-9_]
\S	Not Space Character	[^ \r\t\n\f]