Regex 'If Not Match'

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PugSA has asked for the wisdom of the Perl Monks concerning the following question:

Hi All
This is probably a very bad question but I still need to get my code correct

Could someone tell me how to fix this bad code
I'm not to sure how to 'NOT MATCH'

if($reference =~ m/38[0-9]{8}[A-Z]{3}/)<br>
{
}
else
{
$reference = "";
}
[download]

Comment on Regex 'If Not Match' Download Code

Replies are listed 'Best First'.
Re: Regex 'If Not Match' by Zaxo (Archbishop) on Sep 30, 2005 at 02:46 UTC
The `!~` binding returns true for non-matches, `$reference = '' if $reference !~ m/38[0-9]{8}[A-Z]{3}/;` [download] or to keep the important part first and the match positive, `$reference =~ m/38[0-9]{8}[A-Z]{3}/ or $reference = '';` [download] After Compline, Zaxo	[reply] [d/l] [select]
Re: Regex 'If Not Match' by sh1tn (Priest) on Sep 30, 2005 at 02:46 UTC
`if($reference !~ m/38[0-9]{8}[A-Z]{3}/){ ... }` [download] You may want to read perlre.	[reply] [d/l]
Re: Regex 'If Not Match' by strat (Canon) on Sep 30, 2005 at 03:10 UTC
an alternative is unless which is the contrary to if `unless ($reference =~ m/38[0-9]{8}[A-Z]{3}/) { $reference = ""; }` [download] If possible, I prefer unless way over !~ because I think it is better readable since I sometimes miss !~ at the first fast view to get the structure of a program Best regards, perl -e "s>>F>e=>y)\martinF)stronat)=>print,print v8.8.8.32.11.32"	[reply] [d/l]
Re: Regex 'If Not Match' by Skeeve (Parson) on Sep 30, 2005 at 03:13 UTC
The previouse answers are all correct. But have you really missed the obious way??? `if( not ( $reference =~ m/38[0-9]{8}[A-Z]{3}/ )) { $reference = ""; }` [download] And then there is also another way `unless` you don't like it, you may use: `$reference = "" unless $reference =~ m/38[0-9]{8}[A-Z]{3}/;` [download] `$\=~s;s.;q^\|D9JYJ^^qq^\//\\\///^;ex;print`	[reply] [d/l] [select]
Re^2: Regex 'If Not Match' by kwaping (Priest) on Sep 30, 2005 at 11:00 UTC
Personally, I thought !~ was the obvious way. :)	[reply]
Re: Regex 'If Not Match' by halley (Prior) on Sep 30, 2005 at 19:40 UTC
Last, but not least, let's say that you store your regular expressions in a config file or something. In many such situations, you can't change the application's logic to say "don't match this pattern." Yet, there's still a way, with negative lookahead assertions. `my $re = qr/(?!\A.38[0-9]{8}[A-Z]{3}.\z)/; if ($reference =~ m/$re/) { # 38nnnnnnnnXXX pattern was not found $reference = ""; }` [download] -- `[ e d @ h a l l e y . c c ]`	[reply] [d/l]

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