表达式主体

 class Program
    {
        public string v;
        // 表达式方法
        public void print() => Console.WriteLine(v);
        // 只读属性
        public string Name => v;

        //表达式 get set
        public string Name2
        {
            get => Name;
            set => v = value;
        }
        // 表达式构造
        public Program(string name) => v = name;
        // 终结器/析构函数
        ~Program() => print();

        // 索引器
        public string[] values = {"one","two" };
        public string this[int i]
        {
            get => values[i];
            set => values[i] = value;
        }

        public void test()
        {

            v = "hello";
            print();
            v = "agbc";
            print();

        }
    }

• 表达式