my %hash = ( 'a' => 1, 'b' => 2, 'c' => 3);

foreach (keys %hash) {
  print "$_ => $hash{$_}\n";
}
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To print the values in a hash, use the keys keyword.
 
my %hash = ( 'a' => 1, 'b' => 2, 'c' => 3);

foreach (keys %hash) {
  print "$_ => $hash{$_}\n";
}

  Cheers. :-)

In general, I wouldn't say that. "keys" is a standard Perl function (not a keyword), of which you can omit the () because there is a prototype known for it. Furthermore:
• If you want the values of a hash in no particular order as a list, use the values function.

  my @value = values %hash;
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• If you want the keys of a hash in no particular order as a list, use the keys function.

  my @key = keys %hash;
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• If you want either the values or keys in a particular order, use sort() as well.

  my @value = sort values %hash;
  my @key = sort keys %hash;
  foreach (sort keys %hash) {
      print "$_ => $hash{$_}\n";
  }
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• If you want to show the keys and possibly the associated values in no particular order, use each.

  while (my $key = each %hash) {
      print "$key\n";
  }
  while (my ($key,$value) = each %hash) {
      print "$key => $value\n";
  }
  [download]

The reason for using each() over keys(), is that keys() (and values()) build a list of the values. For large hashes, this list can get very big and cosume a lot of memory. You don't have that when you're using each(), as it will only fetch one key or one key/value pair from the hash at a time.

Liz