Adding values from an array to a hash

[PerlingTheUK]

Dear Monks, I have just found a bug where a code was:

%locations = map{ $_ => 1 } ( @locations );

but should have done

%locations = map{ $_ => 1 } ( @locations, keys %locations );

Now I think that this setup is really annoying, easpecially as I would like rewrite it so that every value is counted to represent how often a location has been added. Is there a way to add onto the old hash instead of completely rewriting it?

[davorg]

Do you mean this:

$locations{$_}++ for @locations;

[blazar]

Now I think that this setup is really annoying, easpecially as I would like rewrite it so that every value is counted to represent how often a location has been added. Is there a way to add onto the old hash instead of completely rewriting it?

I'm not really sure if I understand your question, but you probably either want

%locations=(%locations, map {$_ => 1} @locations);

or

$locations{$_}++ for @locations;

[reneeb]

You can do this:
@locations{@locations} = (1) x scalar @locations