Size of Class in C#

Try see this link
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=1747296&SiteID=1

sorry, on my first post, i mean sizeof(type) not typeof(type)
eg. sizeof(int)

Thanks for reply.
I know sizeof(type) not work for class. And i tried it with Marshal.SizeOf but it not worked, too.
I want to know that becauce i want to know what is disavantage when i create a class which have a lot of method. Should i divide it to many class which inheritance?

I think he's just asking if the number of methods has an affect on the size of the object. Honestly I never even thought about it. It's a good question.

I see... as far as I know people use inheritance for good programming practice and maintainability/reusability...
As for the size and/or performance, I think it would depend on how you implement it.
eg. If you have different classes having same methods
vs if you make a new class containing the common methods, and have the classes inherit from it.
The latter would probably reduce the total size.

Oh... um... I'm not sure either if the number of methods affect the object size... coz I don't know a way to find the size =P

The number of methods shouldn't affect the size of the class object even if they're virtual (in which case the virtual table grows bigger, but not class instances).

that makes the two classes of same size.

This is a very good topic for discussion

As far as, in calculating the size of teh object of a class,
it needs to consider folloiwng points
1) No of parameters and their datatypes
2) Any virtual method
3) Any static variable in class

So the size of teh object totally depends upon the no of parameters and their data types
If you have any virtual method., virtual table is used to store pointers

2 pradipbele:

>> 1) No of parameters and their datatypes
Do you mean member variables? Yes, they are the primary source for object size calculation.

>> 2) Any virtual method
Pointers to these are stored in the vtable, so they don't really affect the size of the object because there's at most one vtable per class, not per object. In C++, no vtable is created for a class with no virtual functions, but in C# I assume it's created anyway to support reflection.

>> 3) Any static variable in class
These do not affect the size of class objects at all, because they're shared by objects of the same class.

Implementing Hardi's reference, types A, C, D, and E below are all of length 119.  Type B is longer, at 150, as one would expect.

using System;
using System.Runtime.Serialization.Formatters.Binary;

[Serializable] class A {
   public int i;
}

[Serializable] class B {
    public A anA = new A();
}

[Serializable] class C {
   public int i;
   public void f() { }
}

[Serializable] class D {
   public int i;
   public virtual void f() { }
}

[Serializable] class E : D {
   public new void f() { base.f(); }
}

class Demo {
   
   static void Main(string[] args) {
      Console.WriteLine("A size = {0}",ObjectSize(new A()));
      Console.WriteLine("B size = {0}",ObjectSize(new B()));
      Console.WriteLine("C size = {0}",ObjectSize(new C()));
      Console.WriteLine("D size = {0}",ObjectSize(new D()));
      Console.WriteLine("E size = {0}",ObjectSize(new E()));
   }

   static long ObjectSize(object o) {
      System.IO.MemoryStream stream = new System.IO.MemoryStream();
      BinaryFormatter objFormatter = new BinaryFormatter();
      objFormatter.Serialize(stream, o);
      return stream.Length;
   }
}

>> Gurudenis:
Yes Exactly. System keeps the information about class in separate memory space