C# Constructors

C# Constructors

A constructor is a special method that is used to initialize objects. The advantage of a constructor, is that it is called when an object of a class is created. It can be used to set initial values for fields:

class Car
{
  public string model;  // Create a field

  // Create a class constructor for the Car class
  public Car()
  {
    model = "Mustang"; // Set the initial value for model
  }

  static void Main(string[] args)
  {
    Car Ford = new Car();  // Create an object of the Car Class (this will call the constructor)
    Console.WriteLine(Ford.model);  // Print the value of model
  }
}

Note that the constructor name must match the class name, and it cannot have a return type (like void or int).

Also note that the constructor is called when the object is created.

All classes have constructors by default: if you do not create a class constructor yourself, C# creates one for you. However, then you are not able to set initial values for fields.

using System;

class Car
{
  public string model;

  public Car()
  {
    model = "Mustang";
  }

  static void Main(string[] args)
  {
    Car Ford = new Car();
    Console.WriteLine(Ford.model);
  }
}

using System;

class Car
{
  public string model;

  public Car(string modelName)
  {
    model = modelName;
  }

  static void Main(string[] args)
  {
    Car Ford = new Car("Mustang");
    Console.WriteLine(Ford.model);
  }
}

using System;

class Car
{
  public string model;
  public string color;
  public int year;

  public Car(string modelName, string modelColor, int modelYear)
  {
    model = modelName;
    color = modelColor;
    year = modelYear;
  }

  static void Main(string[] args)
  {
    Car Ford = new Car("Mustang", "Red", 1969);
    Console.WriteLine(Ford.color + " " + Ford.year + " " + Ford.model);
  }
}