[RESOLVED] A question of efficiency

nrg_alpha

As a matter of code speed / efficiency, which method is faster on execution?
(the number has been reduced to 5 for demonstrative simplicity)

Method 1:

$chance = rand (0,5);
switch($chance){
	case 0:
		$chance = 'axe'; break;
	case 1:
		$chance = 'handle'; break;
	case 2:
		$chance= 'beak'; break;
    case 3:
		$chance= 'hammer'; break;
    case 4:
		$chance= 'snow'; break;
    case 5:
		$chance= 'bird'; break;
    default: echo 'Error...'; break;
}

Method 2:

$translate = array(0=>'axe', 1=>'handle', 2=>'beak', 3=>'hammer', 4=>'snow', 5=>'bird');
$chance = strtr(($chance = rand (0,5)), $translate);

NogDog

Unless I'm missing something, the strtr() seems unnecessary in the second method. Wouldn't it be simpler to just do:

$translate = array('axe', 'handle', 'beak', 'hammer', 'snow', 'bird');
$chance = array_rand($translate);

nrg_alpha

Ah, I was never aware of array_rand().. I can see where this new alternative is even better (I assume) than the examples I initially gave out.

One thing with your sample however is it outputs the key (as opposed to its value).. [when I echo out $chance]. How would I output the value instead? Maybe I'm simply tired and near brain dead on this one...

I do like the direction on this one though.

NogDog

Ah, I always forget that array_rand() does the key instead of the value. You just change it to:

$chance = $translate[array_rand($translate)];

If you already know what the size is of the array, you could just call rand() instead, it might be just a tad faster:

$chance = $translate[rand(0,4)];

But the array_rand will work with any type/size of array without having to worry about how many elements are in it and whether they are sequentially numbered.

nrg_alpha

NogDog;10885197 wrote:
$chance = $translate[array_rand($translate)];

This part did the job perfectly. Thanks 🙂

So I suppose:

$translate = array('axe', 'handle', 'beak', 'hammer', 'snow', 'bird'); 
$chance = $translate[array_rand($translate)];
echo $chance;

is ultimately faster/ more efficient than any of the original examples I showed?
(it would seem so, as there is no involvement of strtr() nor any switch / case checking.

laserlight

I am not sure about efficiency, but the array method would be a little better for maintenance: a switch requires you to change the numbers in two places, while with the array you only change the array.

NogDog

I'm not going to guarantee it's faster, though I'd be very surprised if it were slower in any amount that mattered. Without knowing all the underlying C code that gets executed, how well the parser optimizes different implementations, etc., I won't claim to be able to answer which is faster, but for the need shown here I would use the array_rand() method and not lose any sleep over its efficiency. 🙂 But if it's really important to save every millisecond (maybe you have an array of a thousand items?), then some empirical testing may be the only way to be sure (and it may vary between platforms and versions).

nrg_alpha

Thanks for the response guys..

Laserlight brings up a good point on maintenance.
As for the speed issue, no need to do any empirical testing lol.. It seems like an overall streamlined solution to me. It works, and I'm again going to assume without strtr and switch/case, it will work just as well, if not better (bonus: less code bloat).

So there we have it folks.. I start with two solutions, and walk away with a third 🙂
I have much to learn indeed.