本文对此进行了很好的解释：
delegate void Del(string s);class TestClass{ static void Hello(string s) { System.Console.WriteLine(" Hello, {0}!", s); } static void Goodbye(string s) { System.Console.WriteLine(" Goodbye, {0}!", s); } static void Main() { Del a, b, c, d; // Create the delegate object a that references // the method Hello: a = Hello; // Create the delegate object b that references // the method Goodbye: b = Goodbye; // The two delegates, a and b, are composed to form c: c = a + b; // Remove a from the composed delegate, leaving d, // which calls only the method Goodbye: d = c - a; System.Console.WriteLine("Invoking delegate a:"); a("A"); System.Console.WriteLine("Invoking delegate b:"); b("B"); System.Console.WriteLine("Invoking delegate c:"); c("C"); System.Console.WriteLine("Invoking delegate d:"); d("D"); }}
