PERL: Comparing two arrays with Regex and a nested foreach not working

Question

I am having trouble with a PERL Script I'm writing to take 1 smaller file and compare each line with the contents of a larger file. I am using a positive look-behind regex statement to find the match and give me just the rest of the line.

When I run the code I see all of the elements of @elements print, with no matches printed until the last line. Without displaying sensitive data this is what I see.

$element[0]

.

$element[30]

[match]

.

The matches for element[30] list perfectly, but I am expecting this to happen for each element, not just last element in the array. Here is my code:

    use strict;
    use warnings;
    open(my $in, "<", "call_types.txt");
    my @elements = <$in>;
    close $in;
    open(my $in, "<", "DNIS.cfg");
    my @dnis = <$in>;
    close $in;

    foreach my $call(@elements){
        print "$call\n";
        foreach my $dn(@dnis){
            if($dn =~ /(?<=$call ).*/){ 
                 print "$&\n";
            }
        }
        print "\n";
    }

Borodin · Accepted Answer · 2014-01-25 03:18:09Z

1

You need to

chomp @elements

before you use the contents, otherwise the contents will match only if the text appears at the end of lines in @dnis.

There is also no point in using a look-behind, and you need to be careful of any regex metacharacters the data may contain. You probably need

print "$1\n" if $dn =~ /(\Q$call\E.*)/;

answered Jan 25, 2014 at 3:18

Borodin

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1 Comment

user3234124 Over a year ago

thank you very much! Chomping the array worked, and thanks for the tip on escaping the variable. I didn't even consider the fact that the variable could contain inadvertent regex commands.

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