Regular Expressions

Examples

• Example:
  

  #!/usr/bin/perl -w
  use strict;
  
  my(@theQuote,$theLine);
  
  @theQuote = ( "Having an open mind is nothing;",
  	      "the object of opening the mind,",
  	      "as in opening the mouth,",
  	      "is to eventually close it again",
  	      "upon something solid. (G.K. Chesterton)" );
  
  foreach $theLine (@theQuote) {
      print "theLine : $theLine\n";
      print "="x40 . "\n";
  
      # Literal matches
  
      if ( $theLine =~ /H/ ) {
  	print "/H/ : $theLine\n";
      }
      if ( $theLine =~ /open/ ) {
  	print "/open/ : $theLine\n";
      }
  
      # Character Classes
      if ( $theLine =~ /[Hh]/ ) {
  	print "/[Hh]/ : $theLine\n";
      }
      if ( $theLine =~ / [Ii][ts] / ) {
  	print "/ [Ii][ts] / : $theLine\n";
      }
  
      # Negation of character classes
      if ( $theLine =~ /[^a]s/ ) {
  	print "/[^a]s/ : $theLine\n";
      }
      if ( $theLine =~ /[^a-z ,;]/ ) {
  	print "/[^a-z ,;]/ : $theLine\n";
      }
  
      # Predefined character classes
      if ( $theLine =~ /\wis\w/ ) {
  	print "/\wis\w/ : $theLine\n";
      }
      if ( $theLine =~ /\sis\s/ ) {
  	print "/\sis\s/ : $theLine\n";
      }
  }
  
  
  [killbill@reepicheep perlclass]$ ./test14.perl
  theLine : Having an open mind is nothing;
  ========================================
  /H/ : Having an open mind is nothing;
  /open/ : Having an open mind is nothing;
  /[Hh]/ : Having an open mind is nothing;
  / [Ii][ts] / : Having an open mind is nothing;
  /[^a]s/ : Having an open mind is nothing;
  /[^a-z ,;]/ : Having an open mind is nothing;
  /siss/ : Having an open mind is nothing;
  theLine : the object of opening the mind,
  ========================================
  /open/ : the object of opening the mind,
  /[Hh]/ : the object of opening the mind,
  theLine : as in opening the mouth,
  ========================================
  /open/ : as in opening the mouth,
  /[Hh]/ : as in opening the mouth,
  theLine : is to eventually close it again
  ========================================
  / [Ii][ts] / : is to eventually close it again
  /[^a]s/ : is to eventually close it again
  theLine : upon something solid. (G.K. Chesterton)
  ========================================
  /[Hh]/ : upon something solid. (G.K. Chesterton)
  /[^a]s/ : upon something solid. (G.K. Chesterton)
  /[^a-z ,;]/ : upon something solid. (G.K. Chesterton)
  [killbill@reepicheep perlclass]$ ./test14.perl