FAQ 4.57 What happens if I add or remove keys from a hash while iterating over it?

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4.57: What happens if I add or remove keys from a hash while iterating over it?

(contributed by brian d foy)

The easy answer is "Don't do that!"

If you iterate through the hash with each(), you can delete the key most
recently returned without worrying about it. If you delete or add other
keys, the iterator may skip or double up on them since perl may
rearrange the hash table. See the entry for "each()" in perlfunc.



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