Description:
------------
---
From manual page: https://php.net/function.array-search
---
If in array integer 0 exists before the searched value exists, 
the search stopped by integer 0 and give as the result the key of integer 0.

Test script:
---------------
$arr[1] = "a";
$arr[2] = 0;
$arr[3] = "c";
$arr[4] = "d";
$key	= array_search("c", $arr);
//Result is 2	- !!! Wrong !!!
$arr[1] = "a";
$arr[2] = "";
$arr[3] = "c";
$arr[4] = "d";
$key	= array_search("c", $arr);
//Result is 3	- OK
$arr[1] = "a";
$arr[2] = "";
$arr[3] = "c";
$arr[4] = 0;
$key	= array_search("c", $arr);
//Result is 3 - OK