$mac2 = $2;
[download]

I.e.:

if ($macs[1] =~ /(\S{17})\|(\S{17})/) {
                print "$macs[0] MAC1: $1\n";
                print "$macs[0] MAC2: $2\n";
                $mac1 = $1;
                $mac2 = $2;
                $mac1 =~ s/:/-/g;                
                $mac2 =~ s/:/-/g;  
                print "Converted Mac1: $mac1 Mac2: $mac2\n";
            }
[download]

$mac1 =~ s/:/-/g;
[download]

update: fixed two missing characters while copying and pasting the original code to change it. Thanks to AnomalousMonk for pointing out.

What do you expect the values of $1 and $2 to be after this line:

s/:/-/g
[download]

You will need to copy the values before doing another regular expression match.

If you look in the output I'm expecting all :'s to be replaced with -'s. This worked for $mac1 but not for $mac2. Not sure what you mean by I'll need to copy the value(especially when I didn't need to for the first variable?). Thanks for looking into this.

$2 is undefined when you assign it to $mac2 because you ran another regex in between, and that regex cleared $2. Assign $2 to $mac2 before the substitution, and it will work OK.

G'day samh785,

The special variables $1, $2, etc. are reinitialized on each match. This includes matches done as part of a substitution. After '$mac1 =~ s/:/-/g;', which contains no captures, both $1 and $2 are uninitialized.

Here's a example:

#!/usr/bin/env perl -l

use strict;
use warnings;

my $string = 'abc|def';

if ($string =~ /(\S{3})\|(\S{3})/) {
    print "After first match (in if condition): \$1=$1 \$2=$2";
    my $whatever = 'blah';
    $whatever =~ s/b/c/;
    print "After second match (in substitution): \$1=$1 \$2=$2";
}
[download]

Output:

After first match (in if condition): $1=abc $2=def
Use of uninitialized value $1 in concatenation (.) or string at ./pm_1
+143443_match_vars.pl line 12.
Use of uninitialized value $2 in concatenation (.) or string at ./pm_1
+143443_match_vars.pl line 12.
After second match (in substitution): $1= $2=
[download]

Assigning $2 to $mac2 before attempting the substitution should fix your problem.

Makes sense and that fixed my issue. Thanks! A little upset that I forgot substituting would reset my values... :'(

I find it's good practice to "capture" your capture variables immediately after a match even when you know for sure you will never be doing any further regex matching within that scope:

if ($macs[1] =~ /(\S{17})\|(\S{17})/) {
    my ($mac1, $mac2) = ($1, $2);
    ...
    $mac1 =~ s/.../etc/g;
    $mac2 =~ s/as/needed/g;
    ...
    do_something_with($mac1, $mac2);
    ...
    }
[download]

Just make this same, silly mistake as many times as I have and you'll never do otherwise!

---

Give a man a fish:  <%-{-{-{-<

Just a thought. Since you are only switching one character you could use y/// or tr/// instead of s/// and you would not overwrite your match/capture variables. Like: tr/:/-/.

Ron