string selection from a character class

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

Replies are listed 'Best First'.
Re: string selection from a character class by Limbic~Region (Chancellor) on Jul 12, 2007 at 15:04 UTC
karden, I believe you misunderstand how character classes work. A character class represents a single character and to capture, you put the parens around the class: `/foo="([^"]+)"/` [download] That will capture all the non-quote characters in between two quote characters. I think what you are looking for is assertions. See perlre and the tutorial Using Look-ahead and Look-behind. Cheers - L~R	[reply] [d/l]
Re: string selection from a character class by FunkyMonk (Bishop) on Jul 12, 2007 at 15:09 UTC
How can I capture a string inside such a character class? Anything special with it? I don't know what you mean by this. Can you explain it further? Or, better still, give some sample data and your expected matches. The rules change inside a character class. Outside a character class, `\S+` matches one or more non-space characters. Inside, it matches a single non-space character OR a plus.	[reply] [d/l]
Re: string selection from a character class by karden (Novice) on Jul 12, 2007 at 15:37 UTC
Let me clarify. I expect either of the following as $word in the previous code: `0` or `1 t=something` And I want to capture the word "something". I guess I cannot capture due to Perl matching greedy?	[reply] [d/l] [select]
Re^2: string selection from a character class by toolic (Bishop) on Jul 12, 2007 at 15:51 UTC
`#!/usr/bin/env perl use warnings; use strict; while (<DATA>) { print $2 . "\n" if /(\d)\st=(\w+)/; } __DATA__ 0 1 t=something 2 t=3foo7bar` [download] Creates the following output: `something 3foo7bar` [download] Is this what you are trying to achieve? In any case, you should heed Limbic~Region's advice on understanding character classes (what goes into square brackets in a regex.)	[reply] [d/l] [select]
Re^3: string selection from a character class by karden (Novice) on Jul 12, 2007 at 16:16 UTC
Thx toolic Your solution is exactly the solution I also am using to overcome and it works enough for me. Before my very first posting I was doing (in a loop): `$word =~ /^(\d)\st=(\S+)/; next if ($1 == 0); print "$2\n";` [download] But in this way, for $word="0", pattern was not matched so previous loop's $1 and $2 was printed. And program functioned incorrectly. Anyway, now I am doing: `next if(!($word =~ /(\d)\st=(\S+)/)); print "$2\n";` [download] and it works ok for my task. I thank you for your replies.	[reply] [d/l] [select]
Re^2: string selection from a character class by moritz (Cardinal) on Jul 12, 2007 at 15:54 UTC
You don't need character classes for that: `m/ (\d+) \s t= (\S+) /xms` This allows one t=something string, if you want multiple, you could do something like this: `m/ (\d+) (?: \s t= (\S+) ) /xms` Perl 6 in German	[reply] [d/l] [select]