use strict;
use warnings;

my @array = qw (zero one two);
my $str = "blah ##REP0## blah ##REP1##\nblah ##REP2##\n";

$str =~ s/##REP(\d+?)##/$array[$1]/g;

print $str;
[download]

Update: Another idea is to replace the ##*##'s with %s and do:

$str = sprintf ($str, @array);

Just a thought ...

Zenon Zabinski | zdog | zdog@perlmonk.org