minte9
LearnRemember / REGEX



Non capturing

The preceding =~ links m/.../ with the string to be searched. 
 
#!/bin/perl -l
=begin

The surrounding ^$ ensures that the entire string contains only digits
You can use the special notation (?: ), which group but not capture
This ?: has no relation to the optional ? metacharacter

=cut

$s = '0728824242';
$p = '^[0-9]+$';

if ($s =~ m/$p/) {
    print 'only digits';
}

$s = '-98.6 F';
$p = '^([-+]?[0-9]+(\.[0-9]*)?) (?:[CF])$';

if( $s =~ m/$p/) {
    print $1; # -98.6
    print $2; # .6
    print $3; # null, not captured
}






Questions and answers




Group and non-capture regex in Perl?

  • a) ([0-9]+)?
  • b) (?:[0-9]+)

Perl syntax to match a regex

  • a) $str = /m ^[0-9]+$ /
  • b) $str =~ m/.. /


References