Abigail,

That was an off the cuff remark about using for(;;) instead of for ($lower..$upper). Of course there are uses of for(;;) that do not map on to for ($i..$j). However this wasnt one of them. And for this type of case I stand by my remarks.

Furthermore comparing 

for (my $i = 0; $i < 1000000; $i += 2) {$sum += $i}

[download]
to 
for my $i (map {$_ * 2} 0 .. 1000000 / 2) {$sum += $i}

[download]
is a bit strange, when internally it is closer to 
{
 my $i=0;
 while ($i < 1000000) {
    $sum+=$i;
 } continue {
    $i+=2;
 }
}

[download]
As for all the other languages you listed, none (that I know of) but the C derivatives have this weird form of while loop pretending to be a for loop. For a programmer whose experience is limited to one of the ones without the equivelence the construct is particularly confusing. So from that POV I stand by calling the three arg for loop construct a dirty C trick.

And I stand by the efficiency claims for the case to which I was primarily referring: 

use strict;
use Benchmark qw(cmpthese);
our $sum;

cmpthese -10,{ 'foreach' => <<'CODE', 'for(;;)' => <<'MORECODE' };
$::sum=0;
for my $i (0..10_000) { $::sum+=$i; }
CODE
$::sum=0;
for (my $i=0;$i<10_000;$i++) { $::sum+=$i; }
MORECODE

__END__
Benchmark: running for(;;), foreach, each for at least 10 CPU seconds.
+..
   for(;;): 11 wallclock secs (10.61 usr +  0.00 sys = 10.61 CPU) @ 85
+.30/s (n=905)
   foreach: 11 wallclock secs (10.63 usr +  0.00 sys = 10.63 CPU) @ 14
+3.15/s (n=1521)
          Rate for(;;) foreach
for(;;) 85.3/s      --    -40%
foreach  143/s     68%      --

[download]
Id say thats more efficient wouldnt you?

--- demerphq
my friends call me, usually because I'm late....

In reply to Re: Re: extracting corresponding values from another array by demerphq
in thread extracting corresponding values from another array by Anonymous Monk

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