Use ref to pass a value type by reference : ref « Language Basics « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Language Basics
3. ref

The ref parameter modifier causes C# to create a call-by-reference, rather than a call-by-value.

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); 
  } 
}

a before call: 10
a after call: 100