perl 中如何确定量个HASH表是完全相同的

写了三个HASH进行比对，以便参考
#!/usr/bin/perl -w

my %hash1 = (
'a','B',
'2','D',
'c','X',
);

my %hash2 = (
'a','B',
'2','D',
'c','X',
);

my %hash3 = (
'a','A',
'2','D',
'c','X',
);
# 判断 hash1 和 hash2 是不是完全一样
my $c = 1;
foreach (keys %hash1){
$c = 0 unless exists $hash2{$_};
}
if ($c){
print "\%hash1 == \%hash2\n";
}
else {
print "\%hash1 != \%hash2\n";
}

# 判断 hash1 和 hash3 是不是完全一样
my $d = 0;
foreach (keys %hash1){
$d = 0 unless exists $hash3{$_};
}
if ($d){
print "\%hash1 == \%hash3\n";
}
else {
print "\%hash1 != \%hash3\n&qu