Question

Doing a var_dump on an object from either of the two classes gives the same result

Class Node{
    public $parent = null;
    public $right = null;
    public $left = null;        
    function __construct($data){
        $this->data = $data;                    
    }
}

Class Node{
    public $parent;
    public $right;
    public $left;        
    function __construct($data){
        $this->data = $data;                    
    }
}

For example

$a = new Node(2);
var_dump($a);

returns the following for either of the above classes

object(Node)#1 (4) {
  ["parent"]=>
  NULL
  ["right"]=>
  NULL
  ["left"]=>
  NULL
  ["data"]=>
  int(2)
}

This doesn’t seem to be the case for variables.

$b;
var_dump($b);

If you intend for the property to have a value of null is there a need to explicitly write that since php seems to do it automatically for you?

Also – According to this answer https://stackoverflow.com/a/6033090/784637, C++ gives undefined behavior if you try to get the value of an uninitialized variable. Does C++ automatically set the value of a property in a class to null the way php does, if that property is uninitialized to a value?

Answer 1

No, there is no need to initialize them to null — PHP does this automatically and doing it yourself does not produce any observable difference.

C++ does not set values of class fields to null (there is actually no “real” null value in C++ unless you count nullptr in C++ 11); it zero-initializes or value-initializes them, which is not the same. You can read about zero- and value-initialization here.