benchmark.pl

#!/usr/bin/env perl

use strict;
use warnings;

use Benchmark qw(:all) ;

my $line = "ACGT" x 1_000_000;

my @order = qw(A C G T);

sub counting_with_regexp {
  my %nucleotides = (
    A => 0,
    C => 0,
    G => 0,
    T => 0,
  );

  for my $letter ( keys( %nucleotides ) ) {
    $nucleotides{$letter} += ( () = $line =~ /$letter/g );
  }
}

sub counting_with_substr {
  my %nucleotides;
  for my $i (0..length($line)) {
    my $char = substr($line,$i,1);
    $nucleotides{$char}++;
  }
}

timethese(10, {
  "counting with regexp" => \&counting_with_regexp,
  "counting with substr" => \&counting_with_substr,
});