use strict;
use warnings;

my @array;
push @array, (int rand 50) + 1 for 1 .. 20;

print qq{@array\n};

my @keep = ();
for my $index (0 .. $#array)
{
    push @keep, $index if $array[$index] % 2;
}

@array = @array[@keep];

print qq{@array\n};