You should just uppercase the string to start with as this is a very efficient operation in Perl.

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

my $info = "one:two:three:four";
$info = uc($info);
my @arr = split(/:/, $info);

print "@arr\n";
__END__
Prints:
ONE TWO THREE FOUR
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This is the SAME thing:

my $info = "one:two:three:four";
my @arr = split(/:/, uc($info) );
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In Perl uc($var), upper case works on the entire string of $var.