Question

I need to walk over an array, and conditionally delete elements, in Perl. I know about slice, but am not sure how to use it in a foreach context.

In Ruby, there is reject!:

foo = [2, 3, 6, 7]
foo.reject! { |x| x > 3 }
p foo   # outputs "[2, 3]"

Is there a Perl equivalent?

Answer 1

You can use Perl’s grep which acts like an inverted reject: it will keep all items which satisfy the condition. So reject x > 3 must become grep x <= 3:

@foo = (2, 3, 6, 7);
@foo = grep { $_ <= 3 } @foo;
print @foo; # 23

The condition does not have to be a numeric comparison but can be anything that works in boolean context, e.g. matching against a regular expression.