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

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

    Don't do that. :-)

    [lwall] In Perl 4, you were not allowed to modify a hash at all while
    iterating over it. In Perl 5 you can delete from it, but you still can't
    add to it, because that might cause a doubling of the hash table, in
    which half the entries get copied up to the new top half of the table,
    at which point you've totally bamboozled the iterator code. Even if the
    table doesn't double, there's no telling whether your new entry will be
    inserted before or after the current iterator position.

    Either treasure up your changes and make them after the iterator
    finishes or use keys to fetch all the old keys at once, and iterate over
    the list of keys.

-

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Thu, 12 Aug 2004 08:17:00 GMT  
 
 [ 1 post ] 

 Relevant Pages 

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

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

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

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

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

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

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

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

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

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

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

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

 

 
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