Why casting to object when comparing to null?

Question

While browsing the MSDN documentations on Equals overrides, one point grabbed my attention.

On the examples of this specific page, some null checks are made, and the objects are casted to the System.Object type when doing the comparison :

public override bool Equals(System.Object obj)
{
    // If parameter is null return false.
    if (obj == null)
    {
        return false;
    }

    // If parameter cannot be cast to Point return false.
    TwoDPoint p = obj as TwoDPoint;
    if ((System.Object)p == null)
    {
        return false;
    }

    // Return true if the fields match:
    return (x == p.x) && (y == p.y);
}

Is there a specific reason to use this cast, or is it just some "useless" code forgotten in this example ?

Answer 1

It is possible for a type to overload the == operator. The cast to object ensures that the original definition is used.

Answer 2

As others said, the type might override the == operator. Therefore, casting to Objectis equivalent to if (Object.ReferenceEquals(p, null)) { ... }.