Function to search associative array keys

Question

I am writing a shopping cart session handler class and I find myself repeating this certain chunk of code which searches a multidimensional associative array for a value match.

foreach($_SESSION['cart'] as $k => $v){

    if($v['productID'] == $productID){
        $key = $k;
        $this->found = true;
    }
}

I am repeating this when trying to match different values in the array. Would there be an easy to to create a method whereby I pass the key to search and the value. (Sounds simple now I read that back but for some reason have had no luck)

instead of hardcoding strings just pass variables for whichever key you're looking for. — Colleen
– Colleen, Commented Jan 14, 2013 at 22:29
Literally just findKey($key['SOME_KEY'], $SOME_VALUE) ? No idea why I can't get my head around this simple concept :-S — Insyte
– Insyte, Commented Jan 14, 2013 at 22:31
should be, except instead of 'some_key', do $some_key (I think $, haven't done php in a while, though) so you're using a var instead of the string "some_key" — Colleen
– Colleen, Commented Jan 14, 2013 at 22:32

Jarom · Accepted Answer · 2016-10-12 20:30:14Z

1

Sounds like you want something like this:

function findKey(array $array, $wantedKey, $match) {
    foreach ($array as $key => $value){
        if ($value[$wantedKey] == $match) {
            return $key;
        }
    }
}

Now you can do:

$key = findKey($_SESSION['cart'], 'productID', $productID);

if ($key === null) {
    // no match in the cart
} else {
    // there was a match
}

edited Oct 12, 2016 at 20:30

Jarom

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answered Jan 14, 2013 at 22:38

cmbuckley

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