C#语言入门详解-030泛型、partial类、枚举、结构

泛型（generic）无处不在
- 为什么需要泛型：避免成员膨胀或者类型膨胀
- 正交性：泛型类型（类/接口/委托/……）、泛型成员（属性/方法/字段/……）
- 类型方法的参数推断
- 泛型与委托、lambda表达式
partial类

减少派生的类
partial类与Entity Framework
partial类与Windows Forms、WPF、ASP.NET Core

枚举类型

人为限定取值范围的整数
整数值的对应
比特位式用法

结构体（struct）

值类型，可装/可拆
可实现接口，不能派生自类/结构体
不能有显示无参构造器

[TOC]

泛型类

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using System;

namespace _030_泛型_partial类_枚举_结构体 {
    class Program {
        static void Main(string[] args)
        {
            var apple = new Apple() { Color = "Red" };
            var book = new Book() { Name = "New Book" };
            Box<Apple> box = new Box<Apple>() { Cargo = apple };
            Box<Book> bookBox = new Box<Book>() { Cargo = book };
            Console.WriteLine(box.Cargo.Color);
            Console.WriteLine(bookBox.Cargo.Name);
            Console.ReadKey();
        }
    }

    class Apple {
        public string Color { get; set; }
    }

    class Book {
        public string Name { get; set; }
    }

    class Box<TCargo> {
        public TCargo Cargo { get; set; }
    }
}

泛型接口

using System;

namespace _030_泛型_partial类_枚举_结构体 {
    class Program {
        static void Main(string[] args)
        {
            Student<int> stu=new Student<int>();
            stu.Id = 101;
            stu.Name = "Tim";
            Student<ulong> stu1=new Student<ulong>();
            stu1.Id = 1000000000001;
            stu1.Name = "Jack";
            Stu2 stu2=new Stu2();
            stu2.Id = 100000000000000;
            stu2.Name = "Maomao";
        }
    }

    interface IUnique<TId>
    {
        TId Id { get; set; }
    }

    class Student<TId> : IUnique<TId> {
        public TId Id { get; set ; }
        public string Name { get; set; }
    }

    class Stu2: IUnique<ulong> {
        public ulong Id { get ; set; }
        public string Name { get; set; }
    }
}

泛型数组

static void Main(string[] args)
{
    IList<int> list = new List<int>();
    for (int i = 0; i < 100; i++)
    {
        list.Add(i);
    }
    foreach (int i in list)
    {
        Console.WriteLine(i);
    }
    Console.ReadKey();
}

static void Main(string[] args)
{
IDictionary<int,string> dict=new Dictionary<int, string>();
dict[1] = "Tim";
dict[2] = "Mack";
Console.WriteLine($"student #1 is {dict[1]}");
Console.WriteLine($"student #2 is {dict[2]}");
Console.ReadKey();
}

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泛型方法

static void Main(string[] args)
{
int[] a1 = { 1, 2, 3, 4, 5 };
int[] a2 = { 1, 2, 3, 4, 5, 6 };
double[] a3 = { 1.1, 2.2, 3.3, 4.4, 5.5 };
double[] a4 = { 1.1, 2.2, 3.3, 4.4, 5.5, 6.6 };
var result = Zip(a1, a2);
Console.WriteLine(string.Join(",", result));
var result2 = Zip(a3, a4);
Console.WriteLine(string.Join(",", result2));
Console.ReadKey();
}

private static T[] Zip<T>(T[] a1, T[] a2)
{
T[] zipped = new T[a1.Length + a2.Length];
int ai = 0, bi = 0, zi = 0;
do
{
if (ai < a1.Length) zipped[zi++] = a1[ai++];
if (bi < a2.Length) zipped[zi++] = a2[bi++];
} while (ai < a1.Length | bi < a2.Length);

return zipped;
}

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泛型委托

static void Main(string[] args)
{
    Action<string> a1 = Say;
    a1("Tom");
    Action<int> a2 = Mul;
    a2(3);
    Console.ReadKey();
}

static void Say(string str)
{
    Console.WriteLine($"Hello {str}!");
}

static void Mul(int x)
{
    Console.WriteLine(x * 100);
}

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static void Main(string[] args)
{
Func<int, int, int> func = Add;
var res = func(100, 200);
Console.WriteLine(res);
Func<double, double, double> func2 = Add;
var res2 = func2(23.6, 566.6);
Console.WriteLine(res2);
Console.ReadKey();
}

static int Add(int a, int b)
{
return a + b;
}

static double Add(double a, double b)
{
return a + b;
}

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Func<int, int, int> func = (int a, int b) => { return a + b; };//泛型与lamuda表达式配合使用
var res = func(100, 200);
Console.WriteLine(res);
Func<double, double, double> func2 = (a, b) => { return a + b; };
var res2 = func2(23.6, 566.6);
Console.WriteLine(res2);
Console.ReadKey();

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Partial类

暂缺

枚举

class Program {
    static void Main(string[] args)
    {
        Person person=new Person();
        person.Level = Level.Employee;
        Person boss=new Person();
        person.Name = "Tim";
        person.Skill = (Skill)7;
        boss.Level = Level.Boss;
        Console.WriteLine((int)Level.Employee);
        Console.WriteLine((person.Skill & Skill.Cook) ==Skill.Cook);//比特位用法，捕捉设置就是采用这种方法
        Console.ReadKey();
    }
}

enum Level
{
    Employee=100,
    Manager=200,
    Boss=300,
    BigBoss=400,
}

enum Skill
{
    Drvie=1,
    Cook=2,
    Program=4,
    Teach=8,
}
class Person
{
    public int ID { get; set; }
    public string Name { get; set; }
    public Level Level { get; set; }
    public Skill Skill { get; set; }
}

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结构体类型

using System;
using System.Collections.Generic;

namespace _030_泛型_partial类_枚举_结构体 {
    class Program {
        static void Main(string[] args)
        {
            Student stu = new Student() { Id = 101, Name = "Tim" };
            object obj = stu;//装箱
            Student stu2 = (Student)obj;//拆箱
            stu2.Id = 102;
            stu2.Name = "Mike";
            Console.WriteLine($"#{stu.Id} Name:{stu.Name}");
            Console.WriteLine($"#{stu2.Id} Name:{stu2.Name}");
            stu2.Speak();
            Student stu3 = new Student(103, "Jack");
            stu3.Speak();
            Console.ReadKey();
        }
    }

    interface ISpeak {
        void Speak();
    }
    struct Student : ISpeak {
        public Student(int id, string name)
        {//不能有无参的构造函数，但可以有带参数的
            Id = id;
            Name = name;
        }
        public int Id { get; set; }
        public string Name { get; set; }

        public void Speak()//结构可以调用接口，但不能由其他类或结构体派生
        {
            Console.WriteLine($"Im #{this.Id} Name:{this.Name}!!!!");
        }
    }
}

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