in reply to Re: Re: Add A Number of Days to Today's Date
in thread Add A Number of Days to Today's Date

It makes it obvious what is meant and makes no significant difference to speed whatsoever: 

use Benchmark;

$yours = '
$days = 10;
$then = localtime(time() + $days * 86400);';

$mine = '
$days = 10;
$then = localtime(time() + $days * 24*60*60 );';

timethese ( 100000, { 'yours' => $yours, 'mine' => $mine } );
__END__
Benchmark: timing 100000 iterations of mine, yours...
      mine: 30 wallclock secs (29.95 usr +  0.00 sys = 29.95 CPU) @ 33
+38.89/s (n=100000)
     yours: 30 wallclock secs (29.94 usr +  0.00 sys = 29.94 CPU) @ 33
+40.01/s (n=100000)

[download]

sleep 28800 :-) cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

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Re: Re: Re: Re: Add A Number of Days to Today's Date
by runrig (Abbot) on Sep 29, 2001 at 00:45 UTC
    It makes a bit more difference if you factor in compile time (more tokens to parse, and no optimization of multiplying constants, don't ask me which makes more of a difference):
    use strict;
use warnings;

use Benchmark;
my $x = 5;

timethese(-5, {
 EXPANDED=>sub { eval '$x * 24 * 60 * 60' },
 NOT_EXP =>sub { eval '$x * 86400' },
});

Benchmark: running EXPANDED, NOT_EXP, each for at least 5 CPU seconds.
+..
  EXPANDED:  6 wallclock secs ( 5.31 usr +  0.00 sys =  5.31 CPU) @ 56
+77.40/s (n
=30147)
   NOT_EXP:  6 wallclock secs ( 5.26 usr +  0.00 sys =  5.26 CPU) @ 67
+49.24/s (n
=35501)

    [download]
    But of course I'd leave in the explicit multiplications anyway for reasons already mentioned. If I really needed to eval that, I might put something like $seconds_per_day = 24 * 60 * 60; outside of the eval, then use the variable inside.
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