#!/usr/local/bin/perl -s

use strict;

my ($var) = "This is the line that should be changed.";
my (@old) = split(/ /,$var);

no strict;

   if ($z){
        @old = map { tr/aeiou/AEIOU/; $_;} @old;   #imagine many values here
   } else {
        @old = "\nBlah-Blah\n";
   }

use strict;

#imagine more code here

print "@old\n";