O Wise Ones,

In my quest to compare equivalent regular expressions, I have attempted to reduce duplicate code by moving the "testing" to a subroutine. The odd thing is that when moved into a subroutine, alternation takes about the same time as when using character classes.

-------------
Without the sub:
(Output =
Alternation takes 1.395 seconds.
Character class 0.043 seconds.
)
-------------
use strict;
use Time::HiRes 'time';

sub main {
    my $TimesToDo = 1000;
    my $TestString ="abababdedfg" x 1000;
    
    my $Count = $TimesToDo;
    my $StartTime = time();
    while ($Count-- > 0) {
        $TestString =~m/^(a|b|c|d|e|f|g)+$/;
    }
    my $EndTime = time();
    printf("Alternation takes %.3f seconds.\n", $EndTime - $StartTime)
+;
    
    $Count = $TimesToDo;
    $StartTime = time();
    while ($Count-- > 0) {
        $TestString =~m/^[a-g]+$/;
    }
    $EndTime = time();
    printf("Character class %.3f seconds.\n", $EndTime - $StartTime);

}
unless (caller) {main ()}

[download]

----------
With the sub:
(Output =
Alternation takes 0.000 seconds.
Character class 0.001 seconds.
)
----------
use strict;
use Time::HiRes 'time';

#TimesToDo, TestString, Regex
sub test
{
    my $TimesToDo = shift;
    my $TestString = shift() x 1000;
    
    my $Count = $TimesToDo;
    my $StartTime = time();
    while ($Count-- > 0) {
        $TestString =~m/^$_[2]+$/;
    }
    my $EndTime = time();
    
    return $EndTime - $StartTime;
}
sub main {
    my $result = test(1000,"abababdedfg","(a|b|c|d|e|f|g)");
    printf("Alternation takes %.3f seconds.\n", $result);
    
    $result = test(1000,"abababdedfg","[a-g]");
    printf("Character class %.3f seconds.\n", $result);

}
unless (caller) {main ()}

[download]

Very greatful for any responses!

In reply to Benchmarking regexes by Anonymous Monk

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