Sort hash by values - sorting

Question

This is not how I populated my hash. Just for easier reading, here are its contents, keys are on a fixed length string:
my %country_hash = (
"001 Sample Name New Zealand" => "NEW ZEALAND",
"002 Samp2 Nam2 Zimbabwe " => "ZIMBABWE",
"003 SSS NNN Australia " => "AUSTRALIA",
"004 John Sample Philippines" => "PHILIPPINES,
);
I want to get the sorted keys based on values. So my expectation:
"003 SSS NNN Australia "
"001 Sample Name New Zealand"
"004 John Sample Philippines"
"002 Samp2 Nam2 Zimbabwe "
What I did:
foreach my $line( sort {$country_hash{$a} <=> $country_hash{$b} or $a cmp $b} keys %country_hash ){
print "$line\n";
}
also;
(I doubted this will sort but anyway)
my #sorted = sort { $country_hash{$a} <=> $country_hash{$b} } keys %country_hash;
foreach my $line(#sorted){
print "$line\n";
}
Neither of them sorted correctly. I hope someone could help.

Answer 1

If you had used warnings, you would have been told that <=> is the wrong operator; it is used for numeric comparison. Use cmp for string comparison instead. Refer to sort.
use warnings;
use strict;
my %country_hash = (
"001 Sample Name New Zealand" => "NEW ZEALAND",
"002 Samp2 Nam2 Zimbabwe " => "ZIMBABWE",
"003 SSS NNN Australia " => "AUSTRALIA",
"004 John Sample Philippines" => "PHILIPPINES",
);
my #sorted = sort { $country_hash{$a} cmp $country_hash{$b} } keys %country_hash;
foreach my $line(#sorted){
print "$line\n";
}
This prints:
003 SSS NNN Australia
001 Sample Name New Zealand
004 John Sample Philippines
002 Samp2 Nam2 Zimbabwe
This also works (without the extra array):
foreach my $line (sort {$country_hash{$a} cmp $country_hash{$b}} keys %country_hash) {
print "$line\n";
}