How to use foreach with a hash reference?

Question

I have this code

foreach my $key (keys %ad_grp) {

    # Do something
}

which works.

How would the same look like, if I don\'t have

Answer 1

So, with Perl 5.20, the new answer is:

foreach my $key (keys $ad_grp_ref->%*) {

(which has the advantage of transparently working with more complicated expressions:

foreach my $key (keys $ad_grp_obj[3]->get_ref()->%*) {

etc.)

See perlref for the full documentation.

Note: in Perl version 5.20 and 5.22, this syntax is considered experimental, so you need

use feature 'postderef';
no warnings 'experimental::postderef';

at the top of any file that uses it. Perl 5.24 and later don't require any pragmas for this feature.