FAQ 4.57 What happens if I add or remove keys from a hash while iterating over it?
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From: PerlFAQ Server on 23 Feb 2010 00:00 This is an excerpt from the latest version perlfaq4.pod, which comes with the standard Perl distribution. These postings aim to reduce the number of repeated questions as well as allow the community to review and update the answers. The latest version of the complete perlfaq is at http://faq.perl.org . -------------------------------------------------------------------- 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. -------------------------------------------------------------------- The perlfaq-workers, a group of volunteers, maintain the perlfaq. They are not necessarily experts in every domain where Perl might show up, so please include as much information as possible and relevant in any corrections. The perlfaq-workers also don't have access to every operating system or platform, so please include relevant details for corrections to examples that do not work on particular platforms. Working code is greatly appreciated. If you'd like to help maintain the perlfaq, see the details in perlfaq.pod. |