Lære Constructor Overloading | Constructors and Overloading

Constructor overloading is a technique in C# that allows you to define multiple constructors within the same class, each with a different set of parameters. This feature lets you offer several ways for users of your class to create objects, depending on the information they have available at the time of instantiation. Constructor overloading is especially useful when you want to provide sensible defaults, support optional details, or allow for flexible object creation without requiring users to always supply all possible data.

Program.cs


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using System;

namespace ConsoleApp
{
    public class Student
    {
        public string Name { get; set; }
        public int Age { get; set; }

        // Default constructor
        public Student()
        {
            Name = "Unknown";
            Age = 0;
        }

        // Constructor with name
        public Student(string name)
        {
            Name = name;
            Age = 0;
        }

        // Constructor with name and age
        public Student(string name, int age)
        {
            Name = name;
            Age = age;
        }
    }

    public class Program
    {
        public static void Main(string[] args)
        {
            Student s1 = new Student();
            Student s2 = new Student("Alice");
            Student s3 = new Student("Bob", 21);

            Console.WriteLine($"{s1.Name}, {s1.Age}");
            Console.WriteLine($"{s2.Name}, {s2.Age}");
            Console.WriteLine($"{s3.Name}, {s3.Age}");
        }
    }
}

In the Student class above, you see three constructors. The default constructor sets both Name and Age to default values, allowing you to create a Student without supplying any information. The second constructor lets you specify the Name but leaves Age at its default. The third constructor allows you to set both Name and Age. This approach gives you flexibility: you can create a student with just a name, with both details, or with neither, depending on the context. Constructor overloading ensures that object creation fits a variety of real-world scenarios, making your classes more adaptable.

Rectangle.cs


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namespace ConsoleApp
{
    public class Rectangle
    {
        public int Width { get; set; }
        public int Height { get; set; }

        // Default constructor
        public Rectangle() { }

        // Constructor with width and height
        public Rectangle(int width, int height)
        {
            Width = width;
            Height = height;
        }

        // Constructor with one side (square)
        public Rectangle(int side)
        {
            Width = side;
            Height = side;
        }
    }
}

When you overload constructors, you give users of your class several ways to initialize objects, but you should design these constructors carefully. Avoid having two constructors with the same number and types of parameters in the same order, as this will cause ambiguity and a compile-time error. Instead, ensure that each constructor signature is unique. Use overloading to provide logical, meaningful creation paths, and document what each constructor does. This makes your class easier to use and maintain, and helps prevent confusion for other developers.

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Sektion 1. Kapitel 3

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Program.cs


              12345678910111213141516171819202122232425262728293031323334353637383940414243444546
            
using System;

namespace ConsoleApp
{
    public class Student
    {
        public string Name { get; set; }
        public int Age { get; set; }

        // Default constructor
        public Student()
        {
            Name = "Unknown";
            Age = 0;
        }

        // Constructor with name
        public Student(string name)
        {
            Name = name;
            Age = 0;
        }

        // Constructor with name and age
        public Student(string name, int age)
        {
            Name = name;
            Age = age;
        }
    }

    public class Program
    {
        public static void Main(string[] args)
        {
            Student s1 = new Student();
            Student s2 = new Student("Alice");
            Student s3 = new Student("Bob", 21);

            Console.WriteLine($"{s1.Name}, {s1.Age}");
            Console.WriteLine($"{s2.Name}, {s2.Age}");
            Console.WriteLine($"{s3.Name}, {s3.Age}");
        }
    }
}

Rectangle.cs


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namespace ConsoleApp
{
    public class Rectangle
    {
        public int Width { get; set; }
        public int Height { get; set; }

        // Default constructor
        public Rectangle() { }

        // Constructor with width and height
        public Rectangle(int width, int height)
        {
            Width = width;
            Height = height;
        }

        // Constructor with one side (square)
        public Rectangle(int side)
        {
            Width = side;
            Height = side;
        }
    }
}

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Tak for dine kommentarer!

Sektion 1. Kapitel 3

Constructor Overloading

1. What is constructor overloading?

2. Why might you want to provide multiple constructors for a class?

3. What happens if you define two constructors with the same parameter types in the same order?

Constructor Overloading

1. What is constructor overloading?

2. Why might you want to provide multiple constructors for a class?

3. What happens if you define two constructors with the same parameter types in the same order?