Can I use an instantiated Object as an Array Key?

Question

For example:

$product = new Product(\"cat\");

if(isset($sales[$product])){
     $sales[$product]++;
}
else{
     $sales[$product] = 1;
}

Answer 1

There is a spl_object_hash function for getting unique object id as string, which can be used as array key. http://php.net/manual/en/function.spl-object-hash.php