Cast to object before null check in overriding Equals [duplicate]

Answer 1

Note that this is the VS 2005 documentation. I guess the folks who write the documentation also had the same question and couldn't come up with a good answer; the example was changed for VS 2008. Here is the current version:

public bool Equals(TwoDPoint p)
{
    // If parameter is null, return false.
    if (Object.ReferenceEquals(p, null))
    {
        return false;
    }

    // Optimization for a common success case.
    if (Object.ReferenceEquals(this, p))
    {
        return true;
    }

    // If run-time types are not exactly the same, return false.
    if (this.GetType() != p.GetType())
        return false;

    // Return true if the fields match.
    // Note that the base class is not invoked because it is
    // System.Object, which defines Equals as reference equality.
    return (X == p.X) && (Y == p.Y);
}