remove duplicates characters from string in perl using substitution

Question

How to remove duplicates characters from string in perl? i tried it using /d but result not match as required.

I already tried:

$string="vvvviiiiiipppppppiiiiinnnnn";
$string=~tr/a-z/a-z/s;
print $string;  

output: vipin, but I want: vipn

Answer 1

my %uniq;
$string = join '', grep !$uniq{$_}++, split //, $string;

or

use List::Util ();
$string = join '', List::Util::uniqstr( split //, $string );