How do I remove duplicate items from an array in Perl?

Question

I have an array in Perl:

my @my_array = ("one","two","three","two","three");

How do I remove the duplicates from the array?

Answer 1

You can do something like this as demonstrated in perlfaq4:

sub uniq {
    my %seen;
    grep !$seen{$_}++, @_;
}

my @array = qw(one two three two three);
my @filtered = uniq(@array);

print "@filtered\n";

Outputs:

one two three

If you are aiming for universality, you should take a look at the uniq function. It is included in the core module List::Util as of Perl v5.26.0 (for older versions, use List::MoreUtils). This function differs from the above sketch in that it treats undef as a separate value, different from '', and does not issue a warning.