The '%hash = undef' is incorrect: 
$ perl -wle '%hash = undef; print scalar %hash'
Odd number of elements in hash assignment at -e line 1.
Use of uninitialized value in list assignment at -e line 1.
1/8

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It'll create a one element hash, whose key is the empty string, with an undefined value.

The last three solutions modify the hash while iterating over the keys, which should be a no-no. However, I just read that in the documentation of 'each' that deleting the item most recently returned by 'each()' is safe; this feature seems to have been added (or documented) in 5.6.1.

Abigail

In reply to Re: OT: clearing a hash (was: TIMTOWTDI doesn't mean invent an outlandish approach (usually)) by Abigail-II
in thread TIMTOWTDI doesn't mean invent an outlandish approach (usually) by davido

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