I want to sort this thing after string1

It's not very clear exactly what you want to do. This will sort the hash by the values associated with 'key1' in each sub-hash.

foreach my $key (sort { $hash->{$a}{key1} cmp $hash->{$b}{key1} } keys
+ %$hash) {
  ...
}
[download]

Fine, thanks, thats doing exactly what I want :)

Is there a possibility to force the sort function to do so? :)

The keys of your $hash are 1 and 2, so that's what $a and $b refer to in the sort block.

The final piece of the puzzle is going from there to the right value. It looks to me you want the value of "key1". That gives us:

sort { $hash->{$a}{key1} cmp $hash->{$b}{key1} } keys %$hash
[download]

Thanks to your explanation I finally got it. Now I can sort everything ;)

    $hash->{'string1'}{$a}
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That will not work. You can't lookup a hash key by it's value. You mean

    $hash->{$a}{'key1'}
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--shmem

update: missed {$a}, corrected

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

Yes, thats my mistake, sorry. In the original code it is right (I abstracted this one). I'm going to update this in my example. But nevertheless this solution doesn't work. But the both above mentioned do so :)

Um, yes. I forgot about the $a,$b gotcha. <nit> Apart from that mistake, your example hash

$hash = {
  1 => {
    key1 => string1,
    key2 => string2
  }
  2 => {
    key1 => string1,
    key2 => string2
  }
}
[download]

is very badly chosen, since the values for each key of the sub-hashes are identical. What do you expect sort to do for you? ,-) </nit>

--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}