Perl: What is the easiest way to flatten a multidimensional array?

Question

What\'s the easiest way to flatten a multidimensional array ?

Answer 1

Using List::Flatten seems like the easiest:

use List::Flatten;

my @foo = (1, 2, [3, 4, 5], 6, [7, 8], 9);        
my @bar = flat @foo;  # @bar contains 9 elements, same as (1 .. 9)

Actually, that module exports a single simple function flat, so you might as well copy the source code:

sub flat(@) {
    return map { ref eq 'ARRAY' ? @$_ : $_ } @_;
}

You could also make it recursive to support more than one level of flattening:

sub flat {  # no prototype for this one to avoid warnings
    return map { ref eq 'ARRAY' ? flat(@$_) : $_ } @_;
}