Some might consider using
split and an index. The
problem with this solution is that it's really slow,
particularly as the string gets longer.
Here's some benchmarking code that'll show you:
#!/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];
}
And here are the benchmark results:
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)
The
substr method is, obviously, the fastest,
because that's what it's designed to do, basically.
unpack is also quite fast.
split has to split the entire string, construct an
array of length($str) elements, then take an index.
So, the best way is to use substr.