CODEWITHSUNDEEP
phparrays
Jürgen Paul
Jürgen Paul

Reputation: 15017

strpos for arrays

Let's say I have 90 'indexes' in my array and I have a function which checks if that value exists in that array, would it be faster if i used strpos with a String instead?

Instead of using in_array() to 

$data = array('John','Mary','Steven');

It will be

$data = 'John.Mary.Steven';

then I'll just strpos() on that String?

Upvotes: 2

Views: 1820

Answers (3)

Konrad Dzwinel
Konrad Dzwinel

Reputation: 37913

I was quite sure that use of strpos will be slower but I made a test below, and it looks like (at least in this particular case - searching for the last element) strpos is faster than in_array.

$array = array();

for($i=0;$i<10000;$i++) {
    $array[] = md5($i . date('now'));
}

$string = implode('.', $array);

$lastElement = $array[9999];

$start = microtime(TRUE);
$isit = in_array($lastElement, $array);
$end = microtime(TRUE);

echo ($end - $start) . PHP_EOL;

$start = microtime(TRUE);
$pos = strpos($string, $lastElement);
$end = microtime(TRUE);

echo ($end - $start) . PHP_EOL;

Results I'm getting:

0.0012338161468506
0.00036406517028809

Upvotes: 2

Jeremy Harris
Jeremy Harris

Reputation: 24549

According to this test, looping your array and checking with strpos() would be slower than just using in_array(). They claim that in_array() is actually 2.4 times faster than doing a foreach loop with strpos().

On the other hand, a question here on SO seems to indicate otherwise.

Efficiency of Searching an Array Vs Searching in Text.... Which is Better?

If I were you, I would run my own performance tests to see what works best with my specific set of data.

Upvotes: 0

Mark Baker
Mark Baker

Reputation: 212412

Without bothering to profile it, I'd say that imploding to a string followed by strpos would be slower than PHP's built-in in_array() function.... because you're adding all the overhead of converting the entire array (all 90 elements) to a string before you can even use strpos(). Premature Micro-optimisation isn't a good idea, unless you really need it, and then you should test your ideas.

EDIT

If you're using your own function instead of in_array(), it probably is slower, but raises the question "why"?

Upvotes: 3

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