Re: regex: only want [a-zA-Z] and comma chars in a string

This example...
-----

#!/usr/bin/perl -w
use strict;

my %commas = (
    'notalot'               => 1,
    'england,rugby'         => 1,
    'chicken,egg,duck,feet' => 1,

    ',southampton'          => 0,
    'bristol,'              => 0,
    'iran,,canada,france'   => 0,
);

foreach my $key (keys %commas)
{
    unless (($key =~ /^,|,,|,$/))
    {
        print "PASS";
    }
    else
    {
        print "FAIL";
    }
    print  ": $key\n";
}
[download]

----
... seems to work for me. This was it's output:

FAIL: bristol,
PASS: notalot
PASS: england,rugby
FAIL: iran,,canada,france
PASS: chicken,egg,duck,feet
FAIL: ,southampton
[download]

Comment on Re: regex: only want [a-zA-Z] and comma chars in a string Select or Download Code

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Re: Re: regex: only want [a-zA-Z] and comma chars in a string by dragonchild (Archbishop) on Oct 13, 2003 at 23:31 UTC
Ahhh ... the pitfalls of coding to the test cases instead of the specification. The OP specifically stated that he needed the characters to be in the class `[a-zA-Z]`, which your code doesn't check for. Try the following string "1", which should fail. ------ We are the carpenters and bricklayers of the Information Age. The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6 ... strings and arrays will suffice. As they are easily available as native data types in any sane language, ... - blokhead, speaking on evolutionary algorithms Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.	[reply] [d/l]
Re: Re: regex: only want [a-zA-Z] and comma chars in a string by nevyn (Monk) on Oct 14, 2003 at 19:39 UTC
`unless (($key =~ /^,\|,,\|,$/))` Cute, testing for the negative is much more readable here ... but probably something I wouldn't have tried. You need to check for the characters being in the valid class though (and I'd also put brackets around the anchors) so that would make it... `unless (($key =~ /(?:^,)\|,,\|[^a-zA-Z,]\|(?:,$)))` [download] Which isn't quite as nice anymore :(. So I'd probably still use the "obvious" non-negative... `if (($key =~ /^[a-zA-Z]+(?:,[a-zA-Z]+)$))` [download] Or if I was feeling really special, I might even do... `my $field = qr([a-zA-Z]+); if (($key =~ /^$field(?:,$field)$))` [download] ...which is slightly more readable IMO. update (broquaint): changed `<pre>` to `<code>` tags	[reply] [d/l] [select]