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

use Benchmark;

use vars qw/$str/;

$str = "123456789asgdjlaskjglkajblnlbnlaqjteoijqotijwojgl;akjglkj";

timethese(shift || 10000, {
    'unpack' => sub { my $char = getn_unpack($str, 30) },
    'substr' => sub { my $char = getn_substr($str, 30) },
    'split'  => sub { my $char = getn_split($str, 30) }
});

sub getn_unpack {
    return unpack "x" . ($_[1]-1) . "a", $_[0];
}

sub getn_substr {
    return substr $_[0], $_[1]-1, 1;
}

sub getn_split {
    return +(split //, $_[0])[$_[1]-1];
}

##</code><code>##

Benchmark: timing 100000 iterations of split, substr, unpack...
     split: 20 secs (19.39 usr  0.00 sys = 19.39 cpu)
    substr:  0 secs ( 1.78 usr  0.00 sys =  1.78 cpu)
    unpack:  2 secs ( 2.89 usr  0.00 sys =  2.89 cpu)