The <=> operator only works in numeric context. You need the cmp operator instead, which works in string context:

    foreach $keyOut (sort {$a cmp $b} keys %hshOut) {
        ...
    }
[download]

Alternative: use Data::Dumper to dump your hash (assuming you're doing this for debugging purposes and not dumping it for user-viewable data).

----
I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

Note: All code is untested, unless otherwise stated

The keys look something like 465.274. The keys used to be numeric and then they became strings. Thanks for catching this for me.
-P0w3rK!d

It's quite impossible to change a hash-key, they are constant strings - strictly speaking they cannot even be numbers.

The string "465.274" is converted to a number when needed by perl, so that should not give you this warning, as the following code shows:

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

my @array = qw(465.274 21893.32 72.37); # qw creates quoted strings
print for (sort {$a <=> $b} @array);
[download]

output:

72.37
465.274
21893.32
[download]

No warnings at all.

Joost

-- 
#!/usr/bin/perl -np
BEGIN{@ARGV=$0}s(^([^=].*)|=)()s;
=Just another perl hacker\
[download]

Joost

-- 
#!/usr/bin/perl -np
BEGIN{@ARGV=$0}s(^([^=].*)|=)()s;
=Just another perl hacker\
[download]

Sounds like you've got an empty key in there. One fix might be to delete that slice, but you'd be better off figuring out how it got in there in the first place..

delete $hshOut{''};
foreach $keyOut (sort {$a <=> $b} keys %hshOut) {
    ...
}
[download]

cheers,

J