Hi all,
In a recent node there was some discussion about the different ways to get the count of the number of elements in an array. In that thread I expressed my personal preference for scalar(@array) over $#array + 1 or $size = @array. I didn't have any performance timings, so I figured I should see if there really is a difference. This is my timing code:

use strict;
use Benchmark;

my @array = (1..10000000);

timethese(100000000, {
        'scalar'    => \&size_scalar,
        'index'        => \&size_index,
        'context'    => \&size_context
        }
    );

sub size_context { my $val1 = @array; }
sub size_index   { my $val2 = $#array + 1; }
sub size_scalar  { my $val3 = scalar(@array); }

[download]

The results (formatted to look a bit nicer): 
context: 30.52 usr +  0.00 sys = 30.52 CPU @ 3277076.85/s<br>
index:   42.11 usr +  0.00 sys = 42.11 CPU @ 2374732.84/s<br>
scalar:  53.44 usr +  0.00 sys = 53.44 CPU @ 1871327.52/s

[download]

So, two questions here. First, is my test doing a reasonable job of timing? I don't do benchmarks like this often, so I'm worried I've hashed it up. Second, is there any obvious reason why the difference? Is scalar(@array) is slower because it requires a function call?

-Tats

In reply to Timing of Array-Size Determination Methods by Itatsumaki

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