TIMTOWTDI, both are fine.

IIRC old versions of Perl had limitations with map in void context, but that's history.

Some might argue that this is more readable 

for my $key ( keys %hosts ) {
    if ( $hosts{$key} != $table_count ) {
        delete $hosts{$key};
    }
}

[download]

Cheers Rolf

( addicted to the Perl Programming Language)

update

inverted unless to if

update
this works 
while ( my ($key,$value) = each %hosts) {
    delete $hosts{$key}
      if $value != $table_count;
}

[download]

but I'm not sure about side effects!

edit

aha -> each

If you add or delete elements of a hash while you’re iterating over it, you may get entries skipped or duplicated, so don’t. Exception: It is always safe to delete the item most recently returned by "each()", which means that the following code will work: 

while (($key, $value) = each %hash) {
    print $key, "\n";
    delete $hash{$key};   # This is safe
}

[download]

In reply to Re: map {} list or do {} for list? by LanX
in thread map {} list or do {} for list? by Random_Walk

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