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C# Constructors

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:

Example

Create a constructor:

// Create a Car class
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
  }
}

// Outputs "Mustang"

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.

Constructors save time! Take a look at the last example on this page to really understand why.

Continue reading C# Constructors

C# Class Members

Class Members

Fields and methods inside classes are often referred to as “Class Members”:

Example

Create a Car class with three class members: two fields and one method.

// The class
class MyClass
{
  // Class members
  string color = "red";        // field
  int maxSpeed = 200;          // field
  public void fullThrottle()   // method
  {
    Console.WriteLine("The car is going as fast as it can!");
  }
}

Continue reading C# Class Members

C# Multiple Classes and Objects

Multiple Objects

You can create multiple objects of one class:

Example

Create two objects of Car:

class Car
{
  string color = "red";
  static void Main(string[] args)
  {
    Car myObj1 = new Car();
    Car myObj2 = new Car();
    Console.WriteLine(myObj1.color);
    Console.WriteLine(myObj2.color);
  }
}

Continue reading C# Multiple Classes and Objects

C# Classes and Objects

Classes and Objects

You learned from the previous chapter that C# is an object-oriented programming language.

Everything in C# is associated with classes and objects, along with its attributes and methods. For example: in real life, a car is an object. The car has attributes, such as weight and color, and methods, such as drive and brake.

A Class is like an object constructor, or a “blueprint” for creating objects.

Continue reading C# Classes and Objects

C# Method Overloading

Method Overloading

With method overloading, multiple methods can have the same name with different parameters:

Example

int MyMethod(int x)
float MyMethod(float x)
double MyMethod(double x, double y)

Consider the following example, which have two methods that add numbers of different type: Continue reading C# Method Overloading

C# Named Arguments

Named Arguments

It is also possible to send arguments with the key: value syntax.

That way, the order of the arguments does not matter: Continue reading C# Named Arguments

C# Return Values

Return Values

In the previous page, we used the void keyword in all examples, which indicates that the method should not return a value.

If you want the method to return a value, you can use a primitive data type (such as int or double) instead of void, and use the return keyword inside the method: Continue reading C# Return Values

C# Default Parameter Value

Default Parameter Value

You can also use a default parameter value, by using the equals sign (=).

If we call the method without an argument, it uses the default value (“Norway”): Continue reading C# Default Parameter Value

C# Method Parameters

Parameters and Arguments

Information can be passed to methods as parameter. Parameters act as variables inside the method.

They are specified after the method name, inside the parentheses. You can add as many parameters as you want, just separate them with a comma.

The following example has a method that takes a string called fname as parameter. When the method is called, we pass along a first name, which is used inside the method to print the full name: Continue reading C# Method Parameters

C# Methods

A method is a block of code which only runs when it is called.

You can pass data, known as parameters, into a method.

Methods are used to perform certain actions, and they are also known as functions.

Why use methods? To reuse code: define the code once, and use it many times.

Continue reading C# Methods