using System;

public class A{
  private int a, b, c;

  public A(){
    a = 1; b = 2; c = 3;
  }

  public void Swap(ref int v1, ref int v2){   
    int temp;
    temp = v1; v1 = v2; v2 = temp;
  }
 
  public override string ToString(){
    return String.Format("{0} {1} {2}", a, b, c);
  }

  public void Go(){
    Console.WriteLine("{0}", this);
    Swap(ref a, ref b); Swap(ref b, ref c);  
    Console.WriteLine("{0}", this);
  }    

  public static void Main(){
    new A().Go();
  }
}

 
 
 
 
 
 
 
 
 
Two formal reference parameters
 
 
 
 
 
 
 
 
 
 
Actual ref parameters must be variables!