Value Types

• ValueTypes are extended from Object.
• ValueTypes declare their memory on the stack instead of the heap. This means that a ValueType will be deallocated on exiting its scope in which it was defined. In contrast to the managed heap where it would have to wait to be garbage collected.
• Primitive types, enums, and structs are implemented using ValueTypes.
• ValueTypes are copied member-by-member when assigned to a variable or passed as an argument. If a member is a ReferenceType (what classes use) then only its reference will be copied unless IClonable is implemented by the ReferenceType.

Structs

Structs cannot extend classes, or override the default constructor.

Quirk: If you have private fields and properties in a struct with a custom constructor, then you need to call the default constructor in all custom constructors to initialize the fields with default values.

struct Point
{
  private int X { get; set; }
  private int Y { get; set; }
  private string label;

  public Point(string label) : this()
  {
    this.label = label;
  }
}

Nullable

ValueTypes cannot be assigned null. They must be wrapped in Nullable.

System.Nullable<int> i = null;

There is a convenient shorthand for this (?).

int? i = null;
bool? b = null;
float? t = 0.1f;