Regexp pattern match problem

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

Hi Monks,

I was trying to write a script to know if the pattern in file "input.data" match __DATA__. The script as bellow.

#!/usr/bin/perl
use strict;
use warnings;
open FIN, "<input.data" or die $!;
my @line = <FIN>;
close FIN;

while(<DATA>){
    chomp;
    my $data = $_;

    for my $line (@line){
        chomp($line);
        if($data =~ m/$line/){
            print "$line +++++++++ $data\n"
        }else{
            print "$line --------- $data\n"
        }
    }
}


__DATA__
some path/to/foo/bar\[1\]\[2\]
thing apple/flower\[7\]
gogo dog/cat\[9\]\[8\]
[download]

Content of file "input.data"

foo/bar\[1\]
dog/cat\[9\]\[8\]
[download]

The expected result is:

foo/bar\[1\] +++++++++ some path/to/foo/bar\[1\]\[2\]
dog/cat\[9\]\[8\] --------- some path/to/foo/bar\[1\]\[2\]
foo/bar\[1\] --------- thing apple/flower\[7\]
dog/cat\[9\]\[8\] --------- thing apple/flower\[7\]
foo/bar\[1\] --------- gogo dog/cat\[9\]\[8\]
dog/cat\[9\]\[8\] +++++++++ gogo dog/cat\[9\]\[8\]
[download]

The actual result is:

foo/bar\[1\] --------- some path/to/foo/bar\[1\]\[2\]
dog/cat\[9\]\[8\] --------- some path/to/foo/bar\[1\]\[2\]
foo/bar\[1\] --------- thing apple/flower\[7\]
dog/cat\[9\]\[8\] --------- thing apple/flower\[7\]
foo/bar\[1\] --------- gogo dog/cat\[9\]\[8\]
dog/cat\[9\]\[8\] --------- gogo dog/cat\[9\]\[8\]
[download]

I was guessing maybe I should add "\" to deal with "\" in the file "input.data". So I did bellow test.

my $t = 'some path/to/foo/bar\[1\]\[2\]';
my $a = 'bar\\[1';

print "match!\n" if($t =~ m/$a/);
[download]

But it still doesn't match!
I'm confused. I should mess up some basic concept.
Could anyone give me a hand? Thanks in advance!
York

Comment on Regexp pattern match problem Select or Download Code

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Re: Regexp pattern match problem
by Samy_rio (Vicar) on Aug 20, 2007 at 07:09 UTC

Hi, Use \Q..\E quotemeta while checking the pattern

#!/usr/bin/perl
use strict;
use warnings;
open FIN, "<C:\\input.data" or die $!;
my @line = <FIN>;
close FIN;

while(<DATA>){
    chomp;
    my $data = $_;

    for my $line (@line){
        chomp($line);
        if($data =~ m/\Q$line\E/){
            print "$line +++++++++ $data\n"
        }else{
            print "$line --------- $data\n"
        }
    }
}

__DATA__
some path/to/foo/bar[1][2]
thing apple/flower[7]
gogo dog/cat[9][8]

input.data
----------
foo/bar[1]
dog/cat[9][8]

Output
------
foo/bar[1] +++++++++ some path/to/foo/bar[1][2]
dog/cat[9][8] --------- some path/to/foo/bar[1][2]
foo/bar[1] --------- thing apple/flower[7]
dog/cat[9][8] --------- thing apple/flower[7]
foo/bar[1] --------- gogo dog/cat[9][8]
dog/cat[9][8] +++++++++ gogo dog/cat[9][8]
[download]

Not necessary to escape the special character in input file.

Regards,
Velusamy R.

eval"print uc\"\\c$_\""for split'','j)@,/6%@0%2,`e@3!-9v2)/@|6%,53!-9@2~j';

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