C# Constructors

In C#, a constructor is a special method that is automatically called when an object of a class is created. It is mainly used to initialize objects and set default or custom values for class members.

1. What is a Constructor?

A constructor has the same name as the class and does not have a return type (not even void). It runs automatically when we create an object using the new keyword.

2. Why Constructors are Used?

• To initialize object data
• To set default values
• To simplify object creation
• To avoid repetitive code

3. Default Constructor

A default constructor does not take any parameters. It assigns default values.

class Student
{
    public string name;
    public int age;

    // Default Constructor
    public Student()
    {
        name = "Unknown";
        age = 0;
    }
}

class Program
{
    static void Main()
    {
        Student s1 = new Student();

        Console.WriteLine(s1.name);
        Console.WriteLine(s1.age);
    }
}
    

4. Parameterized Constructor

A parameterized constructor accepts values to initialize objects with custom data.

class Student
{
    public string name;
    public int age;

    // Parameterized Constructor
    public Student(string n, int a)
    {
        name = n;
        age = a;
    }
}

class Program
{
    static void Main()
    {
        Student s1 = new Student("Rahul", 20);
        Student s2 = new Student("Amit", 22);

        Console.WriteLine(s1.name + " " + s1.age);
        Console.WriteLine(s2.name + " " + s2.age);
    }
}
    

5. Constructor Overloading

Constructor overloading means having multiple constructors with different parameters in the same class.

class Student
{
    public string name;
    public int age;

    public Student()
    {
        name = "No Name";
        age = 0;
    }

    public Student(string n)
    {
        name = n;
        age = 0;
    }

    public Student(string n, int a)
    {
        name = n;
        age = a;
    }
}
    

6. Real Example of Constructor

using System;

class Car
{
    public string brand;
    public int year;

    // Constructor
    public Car(string b, int y)
    {
        brand = b;
        year = y;
    }

    public void Show()
    {
        Console.WriteLine($"Car Brand: {brand}, Year: {year}");
    }
}

class Program
{
    static void Main()
    {
        Car c1 = new Car("Toyota", 2020);
        Car c2 = new Car("Honda", 2022);

        c1.Show();
        c2.Show();
    }
}
    

7. Key Points

• Constructor name is same as class name
• No return type in constructor
• Automatically called when object is created
• Used to initialize data
• Supports overloading

8. Conclusion

Constructors are an important part of C# classes. They make object creation easy, clean, and efficient by automatically initializing values.