Octavian Rasnita wrote:
> Hi,
Hello,
> Can anyone explain why:
>
> $i++;
>
> is faster than:
>
> $i = 1;
>
> and even more faster than:
>
> $i += 1;
You have to understand how the CPU and Assembly Language works to truely
understand why one instruction is faster than another. For example, assume a
CPU with the registers A and B:
; $i++
LOAD A from $i
INCR A
STORE A to $i
; $i += 1
LOAD A from $i
LOAD B from #memory_location_of_constant_1
ADD B to A
STORE A to $i
The CPU has to do more work to add two values then to just increment one.
And as to why ++$i is faster than $i++ ... well that it a bit beyond a Perl
beginners list. :-) (And besides, Perl optimizes $i++ to ++$i if the side
effects would not change the result.)
John
--
use Perl;
program
fulfillment
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