c# - 如果 System.Enum 是一个类，它怎么可能也是一个 ValueType？

Question

System.ValueType 是一个类，从它派生的所有内容都是值类型，因此不能是类，因为类是引用类型。

那么怎么可能将 System.Enum(继承 System.ValueType)定义为一个类？

Answer 1

.NET 中的一切都派生自 System.Object:

Both reference and value types are derived from the ultimate base class Object. In cases where it is necessary for a value type to behave like an object, a wrapper that makes the value type look like a reference object is allocated on the heap, and the value type's value is copied into it. The wrapper is marked so the system knows that it contains a value type. This process is known as boxing, and the reverse process is known as unboxing. Boxing and unboxing allow any type to be treated as an object.

http://msdn.microsoft.com/en-us/library/system.valuetype(v=vs.110).aspx