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.
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.