use strict;
use warnings;

my %hash;

print "$^V\n";
print "Empty: !\%hash\n" if !%hash;
print "Empty: ! scalar\n" if ! scalar %hash;
print "Empty: 0 == scalar\n" if 0 == scalar %hash;
print "Empty: ! keys\n" if ! keys %hash;

++$hash{entry};
print "Not empty: \%hash\n" if %hash;
print "Not empty: scalar\n" if scalar %hash;
print "Not empty: 0 != scalar\n" if 0 != scalar %hash;
print "Not empty: keys\n" if keys %hash;