firstkey

Tied-hash iterator: reset and return the first key.

Σύνοψη

my @keys = keys %Config;            # triggers FIRSTKEY + NEXTKEY
while (my ($k, $v) = each %Config) { ... }

Τι επιστρέφεται

The first key in the internal iteration order, or undef if the hash is empty.

Οριακές περιπτώσεις

• Iteration order is unspecified; never rely on it.

• Calling FIRSTKEY resets a NEXTKEY walk in progress.

Διαφορές από το upstream

Fully compatible with upstream.