Re: There's no LIMIT to my SPLITting headache.

Mark Seger wrote:

> The most enlightening experience I've had with perl was discovering that:
>
> statement if $a=~/aaa|bbb|ccc/
>
> is a LOT slower than
>
> statement if $a=~/aaa/ || $a=~/bbb/ || $a=~/ccc/
>
> by a factor of about 7, at least when I checked it out on both a 3.5GHz
> Xeon and a 1.5GHz Intanium 2. The moral to the story is nothing beats a
> few simple tests.

Not by a long shot on my machine, running Perl 5.8.7.

=code

use Benchmark qw(:hireswallclock cmpthese);

my $pat = 'A Perl Paaattern';
my $match = 0;

cmpthese(0, {
'Code1' => '$match = 1 if $pat =~/aaa/ || $pat=~/bbb/ || $pat=~/ccc/',
'Code2' => '$match = 1 if $pat =~/aaa|bbb|ccc/',
});

=cut

Time::HiRes is compiled on my machine.

Granted, that's a *very* simple pattern, but the shorter code came out
ahead 5/5 times by a wide margin.

___________________________
Rate Code1 Code2
___________________________
Code1 2775928/s -- -62%
Code2 7368521/s 165% --
___________________________
Code1 2888905/s -- -63%
Code2 7777375/s 169% --
___________________________
Code2 2647141/s -- -64%
Code1 7289831/s 175% --
___________________________
Code1 2742926/s -- -62%
Code2 7313196/s 167% --
___________________________
Code1 2803761/s -- -61%
Code2 7211258/s 157% --
---------------------------

Or if I set $pat to a string of the output from 'perldoc Time::HiRes'

Code1 2657898/s -- -70%
Code2 8771367/s 230% --


Dave


.

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