Regex: Searching for a string with special characters

[Anonymous Monk]

Hi Monks,

I am having trouble with searching for a string with special characters.

When I have texts without 'brackets' in the SFile, I get the required result but it fails if I want to search for a string with 'brackets'. Could someone help me or point to some documentation? Thanks.

#! /path/to/perl
use strict;
open (MAINFILE, "./TestFile") or die "Can't find file";
open (SFILE, "./SFile") or die "Can't find file";
my $search;
while (<SFILE>) {
    $search = $_;
    print "search string is $search";
}
close ( SFILE );
print "Now opening the main file\n";
while (<MAINFILE>) {
    if ( ! /$search/ ) { print "No Match found\n"; next; }
    else { print "Found $search in main file"; }    
}


TestFile:
Bus
Bus(Mini)
Car
Van

SFile:
Bus(Mini)

[liverpole]

I assume by 'brackets' you mean parentheses? That is, '(' and ')'?

Try using \Q ... \E in your regular expression if you want to 'escape' the string being searched against:

    if ( ! /\Q$search\E/ ) { print "No Match found\n"; next; }

You can find more by reading perlre.

And another option is to use the qr/\Q$search\E/ syntax, which you can find in perlop.

Update:  Fixed wording (thanks for pointing that out, Hofmator++.)

Good luck!

[Hofmator]

And another option is to use the qr/$string/ syntax, which you can find in perlop.

Just a small annotation. This is only correct if it is supposed to be a general comment. The qr/$string/ construct has no influence on the escape issue whatsoever.

For the escaping see also quotemeta.

[Anonymous Monk]

Thanks a lot.

As mentioned by you, 'qr' didn't work for me but I was able to get the desired results using 'quotemeta'.

[GrandFather]

you may also want to remove line ends (chomp).

Update: note that your sample would be better given as follows to avoid external files:

use warnings;
use strict;

my $search = "Bus(Mini)\n";
while (<DATA>) {
    if ( ! /$search/ ) { print "No Match found\n"; next; }
    else { print "Found $search in main file\n"; }    
}

__DATA__
TestFile:
Bus
Bus(Mini)
Car
Van