Re: Stepping through a hash while modifiying its content

If you add or delete a hash's elements while iterating over it, entries may be skipped or duplicated--so don't do that

perlfaq4#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.

Comment on Re: Stepping through a hash while modifiying its content

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Re^2: Stepping through a hash while modifiying its content by Gorgarian (Initiate) on Dec 28, 2012 at 12:13 UTC
OK, thank you for confirming my suspicions, and pointing out the documentation that covers this. I can probably get away with only deleting the most recently returned entry, and not the second entry I reference,though with some considerable increase in runtime. Have a good new year.	[reply]