The Weekly Challenge - 310

TASK #1: Upper Lower
You are given a string consists of english letters only.

Write a script to convert lower case to upper and upper case to lower in the given string. 

#!/usr/bin/perl
use strict;
use warnings;

sub swap_case {
    my ($str) = @_;

    die "Undefined or empty string\n" unless defined($str) && length($str);

     # perfect for ASCII: 
    $str =~ tr/A-Za-z/a-zA-Z/;

    return $str;
}

# Tests

my $str;
$str = "pERl";
printf "%s\n", swap_case($str); # Output: "PerL" 

$str = "rakU";
printf "%s\n", swap_case($str); # Output: "RAKu" 

$str = "PyThOn";
printf "%s\n", swap_case($str); # Output: "pYtHoN"