Can you have a class in a struct?

Question

Is it possible in C# to have a Struct with a member variable which is a Class type? If so, where does the information get stored, on the Stack, the Heap, or both?

Answer 1

Yes, you can. The pointer to the class member variable is stored on the stack with the rest of the struct's values, and the class instance's data is stored on the heap.

Structs can also contain class definitions as members (inner classes).

Here's some really useless code that at least compiles and runs to show that it's possible:

using System;  namespace ConsoleApplication1 {     class Program     {         static void Main(string[] args)         {             MyStr m = new MyStr();             m.Foo();              MyStr.MyStrInner mi = new MyStr.MyStrInner();             mi.Bar();              Console.ReadLine();         }     }      public class Myclass     {         public int a;     }      struct MyStr     {         Myclass mc;          public void Foo()         {             mc = new Myclass();             mc.a = 1;         }          public class MyStrInner         {             string x = "abc";              public string Bar()             {                 return x;             }         }     } } 

Answer 2

The class content gets stored on the heap.

A reference to the class (which is almost the same as a pointer) gets stored with the struct content. Where the struct content is stored depends on whether it's a local variable, method parameter, or member of a class, and whether it's been boxed or captured by a closure.