تعريف البُناة

ما المُنشئ؟

using System;

class Dog
{
    public Dog()
    {
        Console.WriteLine("A dog was created");
    }
}

class Program
{
    static void Main()
    {
        var d = new Dog();
    }
}

المنشئات ذات المعلمات

using System;

class Person
{
    public string Name;
    public int Age;

    public Person(string name, int age)
    {
        Name = name;
        Age = age;
    }
}

class Program
{
    static void Main()
    {
        var p = new Person("Ada", 36);
        Console.WriteLine(p.Name + " is " + p.Age);
    }
}

الكلمة الأساسية this في المنشئات

using System;

class Book
{
    public string Title;

    public Book(string title)
    {
        this.Title = title;
    }
}

class Program
{
    static void Main()
    {
        var b = new Book("C# Basics");
        Console.WriteLine(b.Title);
    }
}

المنشئ الافتراضي

using System;

class Empty
{
    // No constructor written -> compiler supplies a default one
    public int Value;
}

class Program
{
    static void Main()
    {
        var e = new Empty();
        Console.WriteLine("Default Value: " + e.Value);
    }
}

التحقق من الصحة في المنشئ

using System;

class Account
{
    public decimal Balance;

    public Account(decimal initial)
    {
        if (initial < 0)
            throw new ArgumentException("Initial balance cannot be negative");
        Balance = initial;
    }
}

class Program
{
    static void Main()
    {
        var a = new Account(100m);
        Console.WriteLine("Balance: " + a.Balance);
    }
}

التحميل الزائد للمنشئات

using System;

class Point
{
    public int X;
    public int Y;

    public Point()
    {
        X = 0;
        Y = 0;
    }

    public Point(int x, int y)
    {
        X = x;
        Y = y;
    }
}

class Program
{
    static void Main()
    {
        var origin = new Point();
        var p = new Point(3, 4);
        Console.WriteLine(origin.X + "," + origin.Y + " | " + p.X + "," + p.Y);
    }
}

تعيين الخصائص من المنشئ

using System;

class Product
{
    public string Name { get; }
    public decimal Price { get; }

    public Product(string name, decimal price)
    {
        Name = name;
        Price = price;
    }
}

class Program
{
    static void Main()
    {
        var p = new Product("Pen", 1.50m);
        Console.WriteLine(p.Name + ": " + p.Price);
    }
}

القيم الافتراضية للمعلمات

using System;

class Circle
{
    public double Radius;
    public string Color;

    public Circle(double radius, string color = "black")
    {
        Radius = radius;
        Color = color;
    }
}

class Program
{
    static void Main()
    {
        var c1 = new Circle(2);
        var c2 = new Circle(3, "red");
        Console.WriteLine(c1.Color + " | " + c2.Color);
    }
}

تنفيذ العمل في المنشئ

using System;

class Rectangle
{
    public double Width;
    public double Height;
    public double Area;

    public Rectangle(double w, double h)
    {
        Width = w;
        Height = h;
        Area = w * h;
    }
}

class Program
{
    static void Main()
    {
        var r = new Rectangle(4, 5);
        Console.WriteLine("Area: " + r.Area);
    }
}

المنشئات والبيانات المطلوبة

using System;

class User
{
    public string Id;
    public string Email;

    public User(string id, string email)
    {
        Id = id;
        Email = email;
    }
}

class Program
{
    static void Main()
    {
        var u = new User("u1", "a@b.com");
        Console.WriteLine(u.Id + " / " + u.Email);
    }
}

جمع العناصر معًا

using System;

class Temperature
{
    public double Celsius { get; }
    public double Fahrenheit { get; }

    public Temperature(double celsius)
    {
        if (celsius < -273.15)
            throw new ArgumentException("Below absolute zero");
        Celsius = celsius;
        Fahrenheit = celsius * 9 / 5 + 32;
    }
}

class Program
{
    static void Main()
    {
        var t = new Temperature(25);
        Console.WriteLine(t.Celsius + "C = " + t.Fahrenheit + "F");
    }
}

تحقق سريع

مراجعة

using System;

class Demo
{
    public string Name;
    public Demo(string name = "anon")
    {
        this.Name = name;
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine(new Demo().Name);
        Console.WriteLine(new Demo("Kai").Name);
    }
}