[Resolved] php maths - turning positive to negative

Lcousins

Hi! I have a variable $bob which is a whole number between 1 and 6. I want the variable $bobette to be the negative version of $bob, eg a whole number between -1 and -6 based on the value of $bob

what is the quickest way to achieve this??

thanks

ZibingsCoder

shrug

function notAbs ( $num )
{
   return($num - $num - $num);
}

xblue

or (not too php specific either, seems a lot like simple math to me 🙂)

$bobette = -1*$bob;

ZibingsCoder

now I'm curious...

subtraction processed in 0.0000560 seconds
multiplication processed in 0.0000291 seconds

Well...I guess I technically lose then. But I'll be back! I PROMISE!

xblue

Hi, didn't mean to beat you or something. Just proposing an alternative (which I felt was the most common way to do it) - but what about looking for the least common way (no extraordinairy nice idea yet, but I'll think about it), seems more fun anyway?

ZibingsCoder

what about...


$bobette = "-{$bob}";

Lcousins

lol, thanks both, multiple totally valid answers! 😃

laserlight

Well...I guess I technically lose then. But I'll be back! I PROMISE!

Actually, you would have won if you simplified your expression.
$bobette = 0 - $bob;

Subtraction is faster than multiplication.
But you used two subtractions where one was enough.

ZibingsCoder's suggestion is the slowest since there is variable interpolation.
Still, even if concatenation was used, the need to cast to string wastes time, and concatenation is (probably) slower than multiplication.

Installer

Sorry about posting to a resolved thread, but here's another:

$bobette = -$bob;

ZibingsCoder

I started creating an entire class for this today in PHP5 while I was at work, but it appears my client had decided to check in on me today...so that work is gone. teehee