For all upper case or all lower case, just use Text::Autoformat. 
/usr/bin/perl

use strict;
use warnings;
use Text::Autoformat;

my $formatted = autoformat 'WHAT DO YOU WANT RETURNED', 
{ case => 'lower' };
print $formatted;

my $formatted1 = autoformat 'what do you want returned', 
{ case => 'upper' };
print $formatted1;

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In reply to Re: Reversing string case by Khen1950fx
in thread Reversing string case by perlpal

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