Constructors

Learn how constructors initialize objects, including default, parameterized, and overloaded constructors.

C# & .NET learning pathLesson 22 of 66

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What is a Constructor?

A constructor is a special method that runs automatically when an object is created with new. It shares the class's name and has no return type, and is typically used to set up initial values.

Parameterized Constructors

class Student
{
    public string Name;
    public int Age;

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

var student = new Student("Aarav", 20);
Console.WriteLine($"{student.Name} is {student.Age}");

Output

Click Run to see what this code prints.

Constructor Overloading

Like methods, constructors can be overloaded to support creating objects in different ways.

class Student
{
    public string Name;
    public int Age;

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

    public Student(string name) : this(name, 18) // calls the other constructor
    {
    }
}

The this Keyword

this refers to the current object instance. It's especially useful for disambiguating a field from a constructor parameter with the same name.

class Point
{
    public int X;
    public int Y;

    public Point(int x, int y)
    {
        this.X = x; // this.X is the field, x is the parameter
        this.Y = y;
    }
}

FAQs

What if I don't write a constructor at all?

C# provides a free, parameterless default constructor automatically — but only if you don't define any constructor of your own.

Summary

Constructors initialize an object when it's created.
They can be overloaded to support different creation patterns.
this refers to the current instance, useful for resolving naming conflicts.

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