#!/usr/bin/perl -w
use strict;

my $string = '1,2,3';
my @names;

### This prints one line (what you're getting)
@names = ($string);
print +(join '--' => @names), "\n";

### This prints multiple lines (what you want)
@names = split ',' => $string;
print +(join '--' => @names), "\n";
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P.S. Next time use a descriptive title. We know you need help if you're here.