C#有关基类，@符号，nameof，内部类， typeof用法实践

文章内容都是自己学习笔记。

一 基类和枚举

代码

 public class TestPoint
    {

        public int X { get; set; }
        public int Y { get; set; }
        public TestPoint(int x, int y) => (X, Y) = (x,y); //元组

        public void Run()
        {
            Console.WriteLine($"基类方法============数据1:{X},----数据2:{Y}");
        }
    }
    //https://learn.microsoft.com/zh-cn/dotnet/csharp/tour-of-csharp/types
    public class Point3D : TestPoint
    {
        public int Z { get; set; }
        public Point3D(int x,int y,int z) : base(x, y)
        {
            Z = z;
        }

        public void Run2()
        {
            Console.WriteLine($"继承类自己的方法，数据1:{X},----数据2:{Y},-----数据3:{Z}");
        }
    }
       [Flags] //https://www.cnblogs.com/GreenLeaves/p/6752822.html
    public enum Seasons
    {
        None = 0,
        Summer = 1,
        Autumn = 2,
        Winter = 4,
        Spring = 8,
        All = Summer | Autumn | Winter | Spring
    }

二 内部类

代码

  public class Stack<T>
    {
        Entry _top;//字段

        public void Push(T data)
        {
            _top = new Entry(_top, data);//赋值
        }

        public T Pop() //返回泛型删除
        {
            if (_top == null)
            {
                throw new InvalidOperationException();
            }
            T result = _top.Data;
            _top = _top.Next; //重新赋值

            return result;
        }

        class Entry //内部类
        {
            public Entry Next { get; set; }//自己是自己的属性
            public T Data { get; set; }//泛型参数类

            public Entry(Entry next, T data)//内部类构造函数
            {
                Next = next;
                Data = data;
            }
        }
    }

三 有关 nameof ，typeof，@符号用法

代码

    public class Student
    {
        public int stId { get; set; }
        public string stuName { get; set; }

        public int num;

        private string name;
        public string Name
        {
            get => name;
            set => name = value ?? throw new ArgumentNullException(nameof(value)+"777777", $"{nameof(Name)} cannot be null");
                                           //System.ArgumentNullException: Name cannot be null
        }
    }

四 测试代码

            TestPoint a = new TestPoint(10, 20);
            Point3D pc = new Point3D(10, 520, 30);
            TestPoint b = pc; 
            a.Run();
            Console.WriteLine("================分割线1================");
            b.Run();//基类还是只能显示自己有的属性和功能
                    // b.Run2(); 不可用
            Console.WriteLine("===============分割线2=================");
            pc.Run();
            Console.WriteLine("===============分割线3=================");
            pc.Run2();

         

            var spring = Seasons.Spring;
            Console.WriteLine(spring);
            var startingOnEquinox = Seasons.Spring | Seasons.Autumn;
            Console.WriteLine(startingOnEquinox);
            var theYear = Seasons.All;
            Console.WriteLine(theYear);

            Console.WriteLine("==========分割线===========");

            int? optionalInt = default;
             optionalInt=88;
            Console.WriteLine(optionalInt);
            Console.WriteLine("==========分割线===========");
            var sD = new Stack<int>();
            sD.Push(1); // stack contains 1
            sD.Push(10); // stack contains 1, 10
            sD.Push(100); // stack contains 1, 10, 100 
            //原来可以无限包含呀
            Console.WriteLine(sD.Pop()); // stack contains 1, 10
            Console.WriteLine("==========分割线1===========");
            Console.WriteLine(sD.Pop()); // stack contains 1
            Console.WriteLine("==========分割线2===========");
            Console.WriteLine(sD.Pop()); // stack is empty
            Console.WriteLine("==========分割线88888===========");
            Student p1 = new Student();

            string s1 = nameof(p1);
            Console.WriteLine(s1);
            string s2 = nameof(Student);
            string s3 = nameof(p1.stuName);
            string s4 = nameof(Student.stuName);
            string s5 = nameof(p1.num);
            try
            {
                p1.Name = null;
            }
            catch (Exception ex)
            {

                Console.WriteLine(ex);
            }
            Console.WriteLine(p1.Name);
            Console.WriteLine(s2);
            Console.WriteLine(s3);
            Console.WriteLine(s4);
            Console.WriteLine(s5);
            Console.WriteLine("==========分割线2===========");
            var @dataTest = 5;
            var @this = "88888";
            Console.WriteLine(nameof(@dataTest));  // output: dataTest
            Console.WriteLine(dataTest);
            Console.WriteLine(@dataTest);//https://learn.microsoft.com/zh-cn/dotnet/csharp/language-reference/operators/nameof#code-try-0
            Console.WriteLine(@this);
            // Console.WriteLine(this);

            var n1 = typeof(Student).Name;
            var n2 = typeof(int).Name;

            // Fixed code
            var n11 = nameof(Student);
            var n22 = nameof(Int32);
            Console.WriteLine(n1);//Student
            Console.WriteLine(n11);//Student
            Console.WriteLine(n2);//Int32
            Console.WriteLine(n22);//Int32

五 运行结果图

六 结论

基础还是要打牢，学习要持续，不然跟不上变化。