Matching pattern in regular expression with string position

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

I am trying to match the first occurance of a pattern match in a string with that pattern's position in the string.

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

my $variable = "123g 321 123 g 321";

if ($variable =~ /g/) {
    #need the position of the first g here
    #which, should be 3
}
[download]

Any ideas, without touching each character in the string?

Comment on Matching pattern in regular expression with string position Download Code

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Re: Matching pattern in regular expression with string position by BrowserUk (Patriarch) on Aug 09, 2003 at 12:46 UTC
Within the if statement, `my $pos = pos( $variable ) - 1;` [download] should do the trick. See perlfunc:pos for more information. You might also look at perlvar:$+ * pervar:$-, but these are only set when captiring brackets are used. Examine what is said, not who speaks. "Efficiency is intelligent laziness." -David Dunham "When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller If I understand your problem, I can solve it! Of course, the same can be said for you.	[reply] [d/l]
Re: Re: Matching pattern in regular expression with string position by diotalevi (Canon) on Aug 09, 2003 at 13:24 UTC
Either pos() or `$-[0]`. You could also write that as `my $pos = $-[0]`.	[reply] [d/l] [select]
Re: Re: Matching pattern in regular expression with string position by sauoq (Abbot) on Aug 09, 2003 at 19:18 UTC
In order for `pos()` to work, he'll need to add a `/g` modifer. It only works on "global" matches. Also, it's not the scalars `$+` and `$-` which would be of interest but the arrays `@+` and `@-` which would be. Finally, `$+[0]` and `$-[0]` are both useful even without any capturing because they hold offsets from the entire match. In his case, `$-[0]` is exactly what he needs. -sauoq "My two cents aren't worth a dime.";	[reply]
Re: Matching pattern in regular expression with string position by Not_a_Number (Prior) on Aug 09, 2003 at 13:43 UTC
You could also use the `index` function: `my $pos = index $variable, 'g';` dave	[reply] [d/l] [select]