C#方法的重载

        static void Main(string[] arr)
        {
            Console.WriteLine(M(2,3));
            Console.ReadKey();
        }

        public static int  M(int n1, int n2)
        { 
            n1=n1+n2;
            return n1;
        }
        public static string M(string s1, string s2)
        {
            s1 = s1 + s2;
            return s1;
        }
        public static int M(int n1, int n2,int n3)
        {
            n1 = n1 + n2+n3;
            return n1;
        }