Because I'm in such a great mood today, I'll share with you a code sample from my wonderful "CGI Programming With Perl, 2nd edition" book from O'reilly - this book is great if you intend to do a lot of CGI stuff, it really helped me get started and helps me on a regular basis. :)
sub validate_email_address {
  my $addr_to_check = shift;
  $addr_to_check =~ s/("(?:[^"\\]|\\.)*"|[^\t "]*)[ \t](/$1/g;

  my $esc         = '\\\\';
  my $space       = '\040';
  my $ctrl        = '\000-\037';
  my $dot         = '\.';
  my $nonASCII    = '\x80-\xff';
  my $CRlist      = '\012\015';
  my $letter      = 'a-zA-Z';
  my $digit       = '\d';
  my $atom_char   = qq{ [^$space<>\@,;:".\\[\\]$esc$ctrl$nonASCII]};
  my $atom        = qq{ $atom_char+ };
  my $byte        = qq{ (?: 1?$digit?$digit |
                            2[0-4]$digit    |
                            25[0-5]         ) };
  my $qtext       = qq{ [^$esc$nonASCII$CRlist"] };
  my $quoted_pair = qq{ $esc [^$nonASCII] };
  my $quoted_str  = qq{ " (?: $qtext | $quoted_pair )* " };
  my $word        = qq{ (?: $atom | $quoted_str ) };
  my $ip_address  = qq{ \\[ $byte (?: $dot $byte ){3} \\] };
  my $sub_domain  = qq{ [$letter$digit]
                        [$letter$digit-]{0,61} [$letter$digit]};
  my $top_level   = qq{ (?: $atom_char ){2,4} };
  my $domain_name = qq{ (?: $sub_domain $dot )+ $top_level };
  my $domain      = qq{ (?: $domain_name | $ip_address ) };
  my $local_part  = qq{ $word (?: $dot $word )* };
  my $address     = qq{ $local_part \@ $domain };

  return $addr_to_check =~ /^$address$/ox ? $addr_to_check : "";
}

[download]
I know it's not the easiest of things to read when you're new, but hey - it'll validate just about any legal mail you can throw at it, and it even supports someone@somewhere.info where the end is more than the normal 2 or 3 chars like .uk or .com etc. It currently supports from 2-4 characters, but can easily be expanded by adjusting the {2,4} range in $top_level.

HTH,
~Brian

In reply to Re: Regex Tuning by brianarn
in thread Regex Tuning by webadept

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.