If there are some duplicate entries in an array and you want to remove them. How would you do that?

If duplicates need to be removed, the best way is to use a hash.
Eg:

sub uniqueentr {
return keys %{{ map { $_ => 1 } @_ }};
}
@array1 = ("tea","coffee","tea","cola”,"coffee");
print join(" ", @array1), "\n";
print join(" ", uniqueentr(@array1)), "\n";