You can use ref modifier to implement a swap method.
using System; class Test//from w w w.java2 s.c o m { static void Swap (ref string a, ref string b) { string temp = a; a = b; b = temp; } static void Main() { string x = "A"; string y = "book2s.com"; Console.WriteLine (x); Console.WriteLine (y); Swap (ref x, ref y); Console.WriteLine (x); Console.WriteLine (y); } }