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

You could have two arrays:

Array 1 contains the keys:   |  Array 2 contains the values
+--------+-------------+     |  +--------+------------+
| index: | value:      |     |  | index: | value:     |
| 0      | Object(key) |     |  | 0      | sth(value) |
| 1      | Object(key) |     |  | 1      | sth(value) |
+--------+-------------+     |  +--------+------------+

You search for the Object in array 1,
then you pick the index of that Object
use it as index for array 2 and
=> get the value

in php code

public function getValue($ObjectIndexOfYourArray){
  foreach(array1 as $key => $value) {
    if($value == ObjectIndexOfYourArray){
      return array2[$key];
    }
  }
}

I hope it helps