1  static class Program 2     { 3         static void Main(string[] args) 4         { 5  6             Test2(); 7             Console.ReadKey(); 8         } 9 10         public static string FormatWith(this string format, params object[] args)11         {12             return string.Format(format, args);13         }14         public static void Test2()15         {16             string today = "今天是：{0:yyyy年MM月dd日 ddd}";17             //这里调用了扩展方法18             Console.WriteLine(today .FormatWith(DateTime.Today));19         }20     }