[Java知识库]timothy23-什么是类

023 什么是类 · 语雀https://www.yuque.com/yuejiangliu/dotnet/timothy-csharp-023

C#5

数据类型：

类-引用类型-每1个类都是1个自定义引用类型

1.声明变量

2.创建实例-类的实例化-类是实例的模板

反射-不用new操作符创建实例

//反射

Type t = typeof(Student);

默认构造器

//object o1 = Activator.CreateInstance(t);

//实例构造器

object o2 = Activator.CreateInstance(t, 3, "Tom");

//Console.WriteLine(o2.GetType());//HelloClass.Student

//Console.WriteLine(o2.GetType().Name);//Student

//创建出来的t是object类型，需要强转

//1

Student stu3 = (Student)o2;

//2

Student stu4 = o2 as Student;

stu3.Report();

stu4.Report();

dynamic编程

//dynamic编程

Type t2 = typeof(Student);

dynamic stu5 = Activator.CreateInstance(t2, 4, "Jack");

Console.WriteLine(stu5.Name);

构造器和析构器

构造器-和类名相同，无返回值

默认构造器

实例构造器-一旦有了实例构造器，编译器就不会再生成默认构造器

static构造器-只能用来初始化static成员

C#6新语法-字符串解析-cw($"{ID},{Name}");

java/C#-托管类编程语言-Gc垃圾收集器

c/cpp-内存泄漏

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace HelloClass

{

????class Program

????{

????????static void Main(string[] args)

????????{

????????????默认构造器

????????????{}-初始化器

????????????//var stu1 = new Student() { ID = 1, Name = "Timothy" };

????????????实例构造器

????????????//var stu2 = new Student(2, "Tim");

????????????//反射

????????????Type t = typeof(Student);

????????????默认构造器

????????????//object o1 = Activator.CreateInstance(t);

????????????//实例构造器

????????????object o2 = Activator.CreateInstance(t, 3, "Tom");

????????????//Console.WriteLine(o2.GetType());//HelloClass.Student

????????????//Console.WriteLine(o2.GetType().Name);//Student

????????????//创建出来的t是object类型，需要强转

????????????//1

????????????Student stu3 = (Student)o2;

????????????//2

????????????Student stu4 = o2 as Student;

????????????stu3.Report();

????????????stu4.Report();

????????????//dynamic编程

????????????Type t2 = typeof(Student);

????????????dynamic stu5 = Activator.CreateInstance(t2, 4, "Jack");

????????????Console.WriteLine(stu5.Name);

????????}

????}

????class Student

????{

????????public int ID { get; set; }

????????public string Name { get; set; }

????????//static成员

????????public static int Amount { get; set; }

????????public void Report()

????????{

????????????Console.WriteLine("{0},{1}", ID, Name);

????????}

????????//实例构造器

????????public Student(int id, string name)

????????{

????????????this.ID = id;

????????????this.Name = name;

????????????Amount++;

????????}

????????//static构造器

????????static Student()

????????{

????????????Amount = 0;

????????}

????????//析构器

????????~Student()

????????{

????????????Amount--;

????????????Console.WriteLine("bye");

????????}

????}

}