关键字 this 的作用

  public class A
        {
            string Name = "我是一号~~";
            public A(string Name)
            {
                Console.WriteLine("不加this的时候，Name的值为：{0}", Name);   //此时输出 为当前函数自己的变量
                Console.WriteLine("不给成员变量赋传过来的参数Name值，this.Name的值为：{0}", this.Name);    //此时输出 为当前类的成员变量
                this.Name = Name;
                Console.WriteLine("给成员变量赋传过来的参数Name值后，this.Name的值为：{0}", this.Name);    //此时进行了赋值
            }
        }
        static void Main(string[] args)
        {
            Console.WriteLine();
            A a = new A("我是二号~~");
            Console.ReadKey();
        }

public class A
        {
            B b;
            public void Show()
            {
                b = new B(this);
                Console.WriteLine("this代表将要创建的A的对象");
            }
        }
        public class B
        {
            A a1;
            public B(A a2)   //即B的实例中有一个A类型的成员变量
            {
                a1 = a2;
            }
        }
        static void Main(string[] args)
        {
            A a = new A();
            a.Show();
            Console.ReadKey();
        }

        public class Person
        {
            public string personName;
            //定义年龄为可空类型,这样就可以赋予其null值
            public int? personAge;

            //下面前三个构造函数都是去调用参数最多的第四个构造函数,只取它们所需要的部分参数即可
            //这样的做法就是this串联构造函数
            public Person() : this("", 0) { }
            public Person(string name) : this("evan", null) { }
            public Person(int age) : this("", 20) { }
            public Person(string name, int? age)
            {
                this.personName = name;
                //通过 ?? 判断传入的age是否null值；如果属于null值,则赋值100
                this.personAge = age ?? 100;
            }

            public void Display()
            {
                Console.WriteLine("Name:{0},Age:{1}", personName, personAge);
            }
        }

        static void Main(string[] args)
        {
            Person per1 = new Person();
            per1.Display();

            Person per2 = new Person(20);
            per2.Display();

            Person per3 = new Person("evan");
            per3.Display();

            Person per4 = new Person("evan", 20);
            per4.Display();

            Console.ReadLine();      
        }

        public class Demo
        {
            public string Name { get; set; }
            private string[] Sex = new string[3];
            public string this[int Index]
            {
                get
                {
                    if(Index<3)
                    {
                        return Sex[Index];
                    }
                    return null;
                }
                set
                {
                    if(Index<3)
                    {
                        Sex[Index] = value;
                    }
                }
            }
        }
        static void Main(string[] args)
        {
            Demo demo = new Demo();
            demo[0] = "女";
            demo[1] = "男";
            demo[2] = "其他";
            demo.Name = "小明";
            Console.WriteLine("Name为{3}，Sex的三个实例分别为：{0}，{1}，{2}.",demo[0], demo[1],demo[2],demo.Name);
            Console.ReadKey();
        }