Changing keys in a “for ( keys %hash ) {}”-loop

Question

I remember something about not changing the keys in a

for my $key ( keys %hash ) { ...

for example

for my $key ( keys %hash         


        

Answer 1

you cannot rename any key value instead you can delete and create a new one which is not lesser than renaming a key! :-)

for my $key ( keys %hash ) {
    delete $hash{$key}; 
    $hash{$key} = "$key_x";
}