Question

I try to get the array key of matching values.
It looks like that:

$someId = 2

$array[0][id]   = "1";
$array[0][firstname]  = "dude1";

$array[1][id]   = "2";
$array[1][firstname]  = "dude2";

$array[2][id]   = "3";
$array[2][firstname]  = "dude3";

How I get the array key e.g. “1” ($array[1]), by matching the var “$someId = 2” with the unique IDs ( $array[1][id]) in the array?

Basically: $someId === $array[x][id] > returns the array $array[x] where it matches.

Answer 1

A simple foreach will do it:

$someId = 2;

foreach($array as $person)
{
    if($person['id'] == $someId)
    {
        // found a match, do something with $person
        // ...
        break; // remove the break if you want to continue searching after a match
    }
}

If you want the key then change to

foreach($array as $key => $person)