#!/usr/bin/perl -w

use strict;
use Benchmark;

my $string  = "a man, a plan, a canal, panama!";

sub using_regexp {
   $string =~ /^(.)/o;

   return $1;
}

sub using_split {
   return (split('', $string, 2))[0];
}

sub using_substring {
   return substr($string, 0, 1);
}

sub using_unpack {
   return unpack('A1', $string);
}

sub using_reverse_chop {
   return chop reverse $string;
}

timethese(-5, {'Using Regexp'          => \&using_regexp,
               'Using Split'           => \&using_split,
               'Using Substring'       => \&using_substring,
               'Using Unpack'          => \&using_unpack,
               'Using Reverse & Chop'  => \&using_reverse_chop,
               });

##</code><code>##

[earino@localhost earino]$ ./first_char.pl
Can't modify reverse in chop at ./first_char.pl line 27, near "$string;"
Execution of ./first_char.pl aborted due to compilation errors.
[earino@localhost earino]$

##</code><code>##

return chop reverse scalar $str;

##</code><code>##

#!/usr/bin/perl -w

use strict;
use Benchmark;

my $string  = "a man, a plan, a canal, panama!";

sub using_regexp {
   $string =~ /^(.)/o;

   return $1;
}

sub using_split {
   return (split('', $string, 2))[0];
}

sub using_substring {
   return substr($string, 0, 1);
}

sub using_unpack {
   return unpack('A1', $string);
}

sub using_reverse_chop {
   my $str = reverse $string;
   return chop $str;
}

timethese(-5, {'Using Regexp'          => \&using_regexp,
               'Using Split'           => \&using_split,
               'Using Substring'       => \&using_substring,
               'Using Unpack'          => \&using_unpack,
               'Using Reverse & Chop'  => \&using_reverse_chop,
               });

##</code><code>##

Benchmark: running Using Regexp, Using Reverse & Chop, Using Split, Using Substring, Using Unpack, each for at least 5 CPU seconds...
Using Regexp:  5 wallclock secs ( 5.39 usr + -0.01 sys =  5.38 CPU) @ 207251.30/s (n=1115012)
Using Reverse & Chop:  4 wallclock secs ( 5.23 usr +  0.00 sys =  5.23 CPU) @ 255457.74/s (n=1336044)
Using Split:  5 wallclock secs ( 5.25 usr +  0.01 sys =  5.26 CPU) @ 97116.92/s (n=510835)
Using Substring:  5 wallclock secs ( 5.25 usr + -0.02 sys =  5.23 CPU) @ 1009882.22/s (n=5281684)
Using Unpack:  5 wallclock secs ( 5.27 usr +  0.01 sys =  5.28 CPU) @ 260676.33/s (n=1376371)