----- Original Message -----
From: "Glenn Linderman"
.
.
>
> Get a load of this variation:
>
> perl
> use warnings;
> no warnings "once";
> use Benchmark;
>
> @x = (1 .. 1000000);
> @y = (1 .. 1000000);
> @z = (1 .. 1000000);
> @w = (1 .. 1000000);
>
> $z1 = 0;
> $z2 = 0;
> $z3 = 0;
> $z4 = 0;
>
> timethese(10, {
> 'forgrep' => 'for(grep($_ != 3, @w)){ $z4++ }',
> 'next' => 'for(@z) {next if $_ == 3; $z3++}',
> 'brackets' => 'for(@y) {if($_ != 3){$z2++}}',
> 'modifier' => 'for(@x) {$z1++ if $_ != 3}',
> });
>
> print "\n", $z1, " ", $z2, " ", $z3, " ", $z4, "\n";
> __END__
>
> Benchmark: timing 10 iterations of brackets, forgrep, modifier, next...
> brackets: 4 wallclock secs ( 3.73 usr + 0.00 sys = 3.73 CPU) @
> 2.68/s (n=10)
> forgrep: 3 wallclock secs ( 3.19 usr + 0.00 sys = 3.19 CPU) @
> 3.14/s (n=10)
> modifier: 3 wallclock secs ( 2.61 usr + 0.00 sys = 2.61 CPU) @
> 3.83/s (n=10)
> next: 3 wallclock secs ( 2.64 usr + 0.00 sys = 2.64 CPU) @
> 3.79/s (n=10)
>
> 9999990 9999990 9999990 9999990
>
Yeah .... beats me how 'forgrep' could be faster than 'brackets'.
I had also done some timings on use of 'next' and found it to be
inexplicably fast. IIRC, there is very little difference (timewise) between
"next if $_ == 3;" and "if($_ == 3) {next}". At one stage I got the
impression that $_==3 could be evaluated more quickly than $_!=3, but I
don't know if that's so.
Anyway ..... I probably wouldn't understand it even if it was explained to
me :-)
Cheers,
Rob
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