OOP 物件導向程式設計

信息

原始 MD by 琦龍

OOP是什麼?

全名「Object-oriented programming」 物件導向程式設計

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我們為什麼需要物件導向呢?

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想像一下你如果今天寫一個遊戲 你可能會寫一堆函數跟變數 玩家攻擊、玩家血量、敵人攻擊、敵人血量 等等等等...

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如果此時把玩家與敵人包裝成物件 整體程式會比較好理解與規劃

玩家A = new Player(100, 10) // 100血、10攻
敵人B = new Enemy(30, 5) // 30血、5攻
玩家A.attack(敵人B)
敵人B.attack(玩家A)

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OOP with C#

那接下來在C#裡實際介紹OOP 還記得之前的程式碼嗎?

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OOP有幾項基礎知識

• class
• 靜態(static)
• 建構子(Constructor)
• 存取範圍
  • public
  • private
  • protected

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三大特性:

1. 繼承(Inheritance)
2. 封裝(Encapsulation)
3. 多型(Polymorphism)
   • overload
   • override

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實作

• 抽象(abstract)
• 介面(interface) C#修飾詞抽象 vs 介面

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實戰

public abstract class Unit
{
    public string Name { set; get; }
    public int HP { set; get; }
    protected int ATK;
    public abstract void Attack(Unit unit);
}

interface IInfo
{
    void ShowInfo();
}

public class Player : Unit
{
    public Player(string Name, int HP = 100, int ATK = 10)
    {
        this.Name = Name;
        this.HP = HP;
        this.ATK = ATK;
    }
    public override void Attack(Unit unit)
    {
        unit.HP -= this.ATK;
        Console.WriteLine($"玩家 {this.Name} 對敵人 {unit.Name} 造成 {this.ATK} 點傷害");
    }

}

public class Enemy : Unit
{
    public Enemy(string Name, int HP = 30, int ATK = 5)
    {
        this.Name = Name;
        this.HP = HP;
        this.ATK = ATK;
    }
    public override void Attack(Unit unit)
    {
        unit.HP -= this.ATK;
        Console.WriteLine($"敵人 {this.Name} 對玩家 {unit.Name} 造成 {this.ATK} 點傷害");
    }
}

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請實作ShowInfo，讓輸出畫面呈現以下樣式

Player player = new Player("小明");
Enemy enemy = new Enemy("史萊姆");
player.ShowInfo();
enemy.ShowInfo();
player.Attack(enemy);
enemy.Attack(player);
Console.WriteLine("---- END ----");
player.ShowInfo();
enemy.ShowInfo();

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課堂範例(?)

class Program
{
    static void Main(string[] args)
    {
        player p = new player(100, 10);
        player1 pp = new player1(1, 1);
        p.attack();
        pp.attack();
        // new ABC();
        Console.WriteLine("Hello, World!");
    }
    static void sayHi()
    {
        Console.WriteLine("HI");
    }
    static void sayHi(string name, int i, char c)
    {
        Console.WriteLine($"HI, {name}");
    }
}

abstract class ABC{}

class player
{
    protected int HP;
    private int atk;
    public player(int HP, int atk)
    {
        this.HP = HP;
        this.atk = atk;
        Console.WriteLine("123");
    }
    public void attack()
    {
        Console.WriteLine("攻擊!!!");
    }
}

class player1 : player
{
    public player1(int HP, int atk) : base(HP, atk)
    {
    }

    public override void attack()
    {
        Console.WriteLine("攻擊2!!!");
    }
}

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學長示範interface(?)

namespace vscode_test;
class Program
{
    static void Main(string[] args)
    {
        IRepository repo = new OracleRepository();
        controller c = new controller(repo);
        c.store();
    }
}

class controller
{
    IRepository repo;
    public controller(IRepository repo)
    {
        this.repo = repo;
    }
    public void store()
    {
        this.repo.store();
    }
}

interface IRepository
{
    void store();
}

public class MySQLRepository : IRepository
{
    public void store()
    {
        Console.WriteLine("Store somthing to mysql");
    }
}

public class OracleRepository : IRepository
{
    public void store()
    {
        Console.WriteLine("Store somthing to Oracle DB");
    }
}

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不喜歡C#? 參考學長的JS OOP

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End