Use ref to pass a value type by reference : Parameter Reference : Language Basics C# Examples

    
using  System;  
  
class  RefTest  {  
    /*  This  method  changes  its  argument.  
          Notice  the  use  of  ref.  */  
    public  void  sqr(ref  int  i)  {  
        i  =  i  *  i;  
    }  
}  
  
class  MainClass  {  
    public  static  void  Main()  {  
        RefTest  ob  =  new  RefTest();  
  
        int  a  =  10;  
  
        Console.WriteLine("a  before  call:  "  +  a);  
  
        ob.sqr(ref  a);  //  notice  the  use  of  ref  
  
        Console.WriteLine("a  after  call:  "  +  a);  
    }  
}