Other people have answered your main question. Here are answers to your peripheral questions.

To understand the answers, you need to know how a hash works internally. Internally a hash has a set of buckets. There is a function (aka a hash function) that decides what bucket each key should go into. Ideally the assignment of keys to buckets will look random, so if you have enough buckets for your keys, then no bucket has very many keys. But in fact it is deterministic. That means that inserting/retrieving/deleting are always fast, because you only have to work with the handful of keys in a bucket. (Technical note, Perl changes the number of buckets if the hash gets too many keys, thereby keeping the number of keys/bucket down. This operation is known as a "hash split" and is expensive. But it is also rare, and the cost of this operation averages out to a constant per insert. Perl does not try to reclaim memory if a hash shrinks after having grown.)

  1. i thought the ordering of keys/values are or will be random No. Perl walks the buckets in order, and for each bucket walks the contents in order. Since Perl does this the same way for both keys and values, the order will match between them.
  2. my understanding is that the order of keys and values being returned is affected by insertion order. Yes. The assignment of keys to buckets is not affected by insertion order, but the order of keys in buckets can be. (OK, I lied there. It is possible in at least some versions of Perl for the order that keys are added to cause a split to have happened/not happened.)
  3. i also thought that soon if not already the order returned is further randomized for some sort of security thing. Yes. In recent versions of Perl, the hashing function that is used changes every time you run Perl. This is to prevent people from sending you carefully constructed data that causes your keys to all go into one bucket. Since they can't know what hashing function you're using, they have no way to construct a malicious dataset except by accident (and the odds against it are high).
  4. ...will the following really work? Yes. That is because Perl actually runs values first to generate a list, then keys to generate the list of variables, then proceeds to assign the one to the other.

In reply to Re: using values and keys functions by tilly
in thread using values and keys functions by jim_neophyte

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