An unhandled exception of type 'System.NullReferenceException' for XNA Game

Question

I keep getting this message:

An unhandled exception of type 'System.NullReferenceException' on the code below:

        if (position.X >= p.position.X && position.X != p.position.X)
            position.X -= Yspeed;
        if (position.X >= p.position.X && position.X != p.position.X)
            position.X += Yspeed;
        position.Y = position.Y + Yspeed;

Specifically refers to the first line. What i'm trying to do is move the enemy towards the player.

Lucius · Accepted Answer · 2014-05-08 18:45:41Z

1

You are accessing a field or method of a null reference:

MyType instance = null;

// Throws a NullReferenceException because instance is 
// not an actual object but null.
instance.Name = "foo";

So I suppose position or, rather p is unset. If you are using an IDE like Visual Studio use a breakpoint and inspect your variables and check if they actually contain something.

answered May 8, 2014 at 18:45

Lucius

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2 Comments

deathismyfriend Over a year ago

It would have to be p if position is a Vector2. Structs are always initialized to a default value.

Lucius Over a year ago

Yes, yet we don't actually see the declaration of position nor the type definition. It could just as well be a class. But I'm fairly certain that you are right.

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