Welcome to the Monastery, reebee3!

First, your title is a bit misleading, because you're not really trying to find changes in an array, you're trying to find the position of changes between two strings.

With that said, in the example below, I transform the strings into lists (similar to arrays, but not the same) using split, and compare one letter at a time in the loop. $_ contains the number for each iteration in the for loop (which starts at zero) and add one to it to create $pos.

use strict;
use warnings;
use autodie;

my $number_seqs = scalar @ARGV;

if($number_seqs != 2){
  print "Please provide two sequences \n";
}

if (length $ARGV[0] != length $ARGV[1]){
        print "Please ensure the sequences are the same length \n";
        exit;
}

for (0..(length $ARGV[0]) - 1){
    my $first = (split //, $ARGV[0])[$_];
    my $second = (split //, $ARGV[1])[$_];

    if ($first ne $second){
        my $pos = $_++;
        print "pos $pos: $first => $second\n";
    }
}

[download]

I'm pretty sure there are much more efficient ways to do this, but I'm drawing a blank right now.

In reply to Re: Help tracking changes in array by stevieb
in thread Help tracking changes in array by reebee3

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