FAQ 4.63 How do I reset an each() operation part-way through?

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4.63: How do I reset an each() operation part-way through?

(contributed by brian d foy)

You can use the "keys" or "values" functions to reset "each". To simply
reset the iterator used by "each" without doing anything else, use one
of them in void context:

keys %hash; # resets iterator, nothing else.
values %hash; # resets iterator, nothing else.

See the documentation for "each" in perlfunc.

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[Bill H]

I hope this doesnt't sound like a d'oh moment, but am I being lead to
believe that all these years I have been using the following:

foreach $temp (keys(%in))
{
print $in{$temp};
}

I could have been using this instead:

foreach $temp (values(%in))
{
print $temp;
}

Bill H

[Michael Carman]

Bill H wrote:
>
> I hope this doesnt't sound like a d'oh moment, but am I being lead to
> believe that all these years I have been using the following:
>
> foreach $temp (keys(%in))
> {
> print $in{$temp};
> }
>
> I could have been using this instead:
>
> foreach $temp (values(%in))
> {
> print $temp;
> }

In this case, yes. The two loops do the same thing. I've found that in
practice I usually need the key for some reason and end up using the
first form. It's a guilty pleasure when I can iterate over values()
instead. ;)

There is also a third option that's occasionally useful:

while (my ($k, $v) = each %hash) {
print "$k => $v\n";
}

-mjc