in reply to Re^4: Detecting if a scalar has a number or string
in thread Detecting if a scalar has a number or string

For the record, you're absolutely right. Scalar::Util's looks_like_number() is 655% faster than my eval trap fatal warning approach. But for some reason I do get a sort of a kick out of the idea of letting perl (the interpreter) tell me if a scalar is a number, rather than Perl (the script). Consider my solution purely an academic enveavor, and use the module for production code.

The benchmark script: 

use strict;
use warnings;

use Scalar::Util qw/looks_like_number/;

use Benchmark qw/cmpthese/;

sub seems_like_number {
    use warnings qw/FATAL all/;
    eval { $_[0] += 0; };
    return $@ ? 0 : 1;
}


our @strings = map {
    my $element = '';
    if( rand(1) > .5 ) {
        foreach my $n ( 0 .. int(rand(12)) ) {
            $element .= chr( int( rand( 57 ) ) + 65 );
        }
    } else { 
        $element = int( rand( 100_000 ) );
    }
    $element;
} 0 .. 499;

my $count = -5;

cmpthese( $count, {
    'Seems' => 
        'my $res = seems_like_number( $_ ) foreach @strings;',
    'Looks' => 
        'my $res = looks_like_number( $_ ) foreach @strings;',
} );

[download]

The results:

        Rate Seems Looks
Seems 38.8/s    --  -87%
Looks  297/s  665%    --

[download]

Dave

In Section Seekers of Perl Wisdom