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

die "cant find key\n"
        unless ($text->as_string() =~ /KEY=([^&]+)\&/);
    my $key = $1;

[download]
what is this code doing. i dont understand what the regex part should match with
thanks.

Replies are listed 'Best First'.
(jeffa) Re: A regex I cant get my head around
by jeffa (Bishop) on Aug 03, 2002 at 20:56 UTC
    Looks like it is trying to parse key value pairs that are delimited by ampersands ... maybe GET parameters? [^&]+ matches anything that is not an ampersand and the parens around it capture the match into $1. \& matches a mandatory ampersand. Here is some test code to see what is matched and what is not: 
    use strict;

for (qw(foo foo& &foo foo&bar)) {
    /([^&]+)\&/;
    print "$_ - $1\n";
}

    [download]
    Seems to me that the variable $key in your code should be renamed $value, because that is what it is really trying to capture. Also, depending upon what the goal really is for this code, i might suggest using a CPAN module such as URI to pull out the key/value pairs: 
    use strict;
use URI;

my $uri = URI->new();
$uri->query('THING=super%20hero&KEY=foobar');

my %hash = $uri->query_form();

print $hash{KEY}, "\n";

    [download]
    Notice that KEY is last, and it's value is not succeeded by an ampersand.

    jeffa

    L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
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[d/l]
[select]
      Thanks cLive and jeffa, but it has nothing to do with GET params. If 
      $text->as_string() = "startKEY=jdjhjfg8y4uh449845&finish"

      [download]
      what value ids assigned to $key?
[reply]
[d/l]
        Why not find out for yourself? All you need to do is change your code to something like: 
        my $as_string = 'startKEY=jdjhjfg8y4uh449845&finish';
$as_string =~ /KEY=([^&]+)\&/;
print $1, "\n";

        [download]
        Regardless of whether or not this has to do with GET params, you can still use URI to parse any key=value pairs that are delimited by ampersands: 
        use strict;
use URI;

my $uri = URI->new();
$uri->query('startKEY=jdjhjfg8y4uh449845&finish');

my %pair = $uri->query_form();
print $pair{startKEY}, "\n";

        [download]

        jeffa

        L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
[reply]
[d/l]
[select]
Re: A regex I cant get my head around
by cLive ;-) (Prior) on Aug 03, 2002 at 20:47 UTC
    "KEY=", followed by one or more (greedy) not &s, followed by an &

    cLive ;-)

    --
    seek(JOB,$$LA,0);

[reply]
      so if 
      $text->as_string() = "startKEY=jdjhjfg8y4uh449845&finish"

      [download]
      what value ids assigned to $key?
[reply]
[d/l]
        $text->as_string() = "startKEY=jdjhjfg8y4uh449845&finish"

        what value ids assigned to $key?
        jdjhjfg8y4uh449845

        [download]
        -sauoq
"My two cents aren't worth a dime.";
[reply]
[d/l]
[select]
        jdjhjfg8y4uh449845
[reply]

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