#!/usr/bin/perl -w
use strict;

sub1();

sub sub1 {
    my @arr1 = ("dog", "cow", "camel");

    print indexOf(\@arr1, "cow");
}

sub indexOf {
    my $aref = shift;
    my $element = shift;

    my $count=0;
    foreach (@$aref) {
        return $count if($_ eq $element);
        $count++;
    }

    #foreach (@arr1) { }   # WRONG, @arr1 is not in scope
}