# OOP
---
## OOP是什麼?
全名「Object-oriented programming」
物件導向程式設計
----
我們為什麼需要物件導向呢?
----
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...
----
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
```javascript=
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)
```
---
## 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?
----
OOP有幾項基礎知識
* [class](https://learn.microsoft.com/zh-tw/dotnet/csharp/language-reference/keywords/class)
* [靜態(static)](https://ithelp.ithome.com.tw/articles/10213238)
* [建構子(Constructor)](https://learn.microsoft.com/zh-tw/dotnet/csharp/programming-guide/classes-and-structs/using-constructors)
* [存取範圍](https://aihuadesign.com/2020/03/16/access-modifiers-c-sharp/)
- public
- private
- protected
----
[三大特性](https://chenyayi805.medium.com/a7efab9565ad):
1. 繼承(Inheritance)
2. 封裝(Encapsulation)
3. 多型(Polymorphism)
- overload
- override
----
實作
* 抽象(abstract)
* 介面(interface)
[C#修飾詞](https://aihuadesign.com/2020/03/21/modifiers/)
[抽象 vs 介面](https://dotblogs.com.tw/supergary/2020/09/30/InterfaceAndAbstract)
---
## 實戰
```csharp=
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");
}
}
```
----
請實作ShowInfo，讓輸出畫面呈現以下樣式
```csharp=
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();
```
----
課堂範例(?)
```csharp=
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!!!");
}
}
```
----
學長示範interface(?)
```csharp=
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");
}
}
```
----
不喜歡C#?
[參考學長的JS OOP](/@TrafficLight/OOP_slides)
---
# End
{"metaMigratedAt":"2023-06-17T16:32:28.204Z","metaMigratedFrom":"YAML","title":"OOP","breaks":true,"contributors":"[{\"id\":\"8416e9d5-bab3-4b78-8d9b-644817bd3d18\",\"add\":4174,\"del\":65}]"}