Retrieving specific word from a line of text.

gnu@perl has asked for the wisdom of the Perl Monks concerning the following question:

I am reading in text from various files and need to pull out specific regex-s. I can easily perform the action to find the specific pattern I am looking for, but once I have it it is in a line of text delimited by varying characters and at a different offset from the beginning of the line each time.

Can someone tell me how I can get just this phrase from the line of text? What I need to do is find m/.*PNAME:.*/ in the string, once it is found I need to add just "PNAME:\w" to a hash. The part after the ":" will vary and I need to know how many occurances of each variation I have.

What I have so far is the right logic, but I end up with the whole line in $_ placed into the hash. I only want the PNAME:\w part.

I know I'm going to feel stupid when someone points this out, but HELP!.

TIA, Chad.

#!/usr/bin/perl -w

use strict;

my @filelist = < S2002* >;
my %PNODES;


for (@filelist)
{
    open(FILE,$_);
    while (<FILE>)
    {
        if ($_ =~ m/.*PNODE:.*/)
        {
            $PNODES{$_} = 1;
        }
    }
}
[download]

Comment on Retrieving specific word from a line of text. Download Code

Replies are listed 'Best First'.
Re: Retrieving specific word from a line of text. by impossiblerobot (Deacon) on Dec 11, 2002 at 16:48 UTC
To answer your question, you need to use capturing parentheses. Additionally, the leading and trailing `.`s are unnecessary. `m/PNODE:(\w+)/` [download] The part of the regex matched within the parentheses will end up in `$1`. See perlre for more details. Updated:* Added link to perldocs, and decided to assume that he wanted an entire word, rather than a single word character. Impossible Robot	[reply] [d/l] [select]
Re: Retrieving specific word from a line of text. by djantzen (Priest) on Dec 11, 2002 at 16:49 UTC
You just need to capture that section and assign it to the hash. A capture is indicated by parentheses, and the results are stored in `$1` - `$9`. So, try: `if ($_ =~ m/.(PNODE:\w)/) # \w* assuming you want alphanumeric chars +. { $PNODES{$1} = 1; }` [download]	[reply] [d/l] [select]
Re: Re: Retrieving specific word from a line of text. by CountZero (Bishop) on Dec 11, 2002 at 22:46 UTC
As a matter of fact you are not limited to 9 capture variables $1 - $9. Perl will make as many $x-variables as needed. CountZero "If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law	[reply]