The sub is always returning a scalar or a list. Never an array.

The context of the caller is provided to the last expression evaluated in the subroutine. That expression then evaluates to a scalar or list, and that scalar or list is returned.

In your ret_array, a scalar context evaluation of @_ is clearly the number of elements of the _ array, while a list context evaluation is the current contents of the _ array. But it's not "returning" the array. It's returning a copy of the contents (as a list), or the count (as a scalar).

Similarly, for the ret_list subroutine, a scalar context is passed down to the subroutine to cause the last element of that slice to be returned (as a scalar), or in a list context, the entire contents of the _ array are returned (as a list).

Again, at no time is the "array" returned. You're either returning the last expression evaluated in a list context as a list, or the last expression evaluated in a scalar context as a scalar.

-- Randal L. Schwartz, Perl hacker