Lecture 11 Memory Richard Gesick

Memory There is a significant difference between value and reference types.  Value types live within the stack space and are accessible directly.  Reference types live in the heap and are allocated dynamically using the "new" command.  Primitive types like int, float, bool, etc. are value types.

Memory Consider the following code: int x, y; Random r = new Random(); Memory would look like this:

Memory Just as assignment works with value types, assignment makes a copy of the reference stored in one reference type and places that copy into the other reference type.  Imagine that there are two references to the same space in the heap as a result.

Memory The following code: Dog d1 = new Dog(); Dog d2; d2 = d1; Generates the following memory structure:

Garbage Collection When nothing is pointing to a space in the heap, then the Garbage Collector can come along and free up that memory for some other use.

Memory Model References can get as complicated as we'd like.  Consider the following: Player p = new Player(); p.Position = new Vector2(100,100); p.Weapons.Add(new Weapon("sword", new Vector(-1,-1))); p.Weapons.Add(new Weapon("wand", new Vector(-1,-1))); p.CurrentWeapon = p.Weapons[0]; // current weapon sword