Use array_search
to get the key to a value:
$key = array_search(45, $arr);
And if you want to get its position in the array, you can search for the index of the key in the array of keys:
$offset = array_search($key, array_keys($arr));
So with an array like the following you will still get 1
as result:
$arr = array('foo' => 10, 'bar' => 45, 'baz' => 23);
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