Regex : Using a regular expression (perl specific).

There are 3 ways to call a regex:

1. Use: $x =~ //
2. Use: $x =~ m//
   or m## or m"" or m{} or anything else you care to choose
3. Use: qr()
   or qr## or qr"" or qr{}

Why so many ways. First, that's Perl. But it helps with escaping, see examples below. Just choose the delimiters that don't appear inside the rege.

The usual choices are // () ## and ""

$x =~ /andrew/;
$x =~ m/andrew/;
$x =~ m#andrew#;
$x =~ qr(andrew);

#matches speachmarks
$x =~ m/"andrew"/;

#matches HTML tags - there's no need to escape the / in </b>
$x =~ qr# <b>andrew</b> #;