C# value type and String

Question

This is a homework question, which is why it might be somewhat odd(also apologize if the title isn't very good)

Assuming that v1 is a value type of type X that redefines ToString, is there any difference between using Console.WriteLine(v1) and Console.WriteLine(v1.toString())?

Answer 1

The simplest answer is that "yes, there's a difference". Obviously the important thing is that you know what that difference is though. I won't tell you that, but I'll tell you how to investigate it...

• Write a short program which contains a custom value type as described, and both Console.WriteLine(v1) and Console.WriteLine(v1.ToString()) in a Main method
• Compile the program
• Run ildasm (or Reflector in IL mode) and look at the difference between the method invocations
  • Which method overload is invoked in each case?
  • What happens to the value in each case?

Questions which you might want to think about and which might get you extra credit:

• Is there any difference if you use a custom class instead of a struct?
• Can you think of any way that Console.WriteLine could have been designed which would have removed any inefficiency you've noticed?