# Classes

In another file
```C#
class Messages()
{
    public static void Hello()
    {
        Console.WriteLine("Hello! Welcome to the program");
    }
    public static void Waiting()
    {
        Console.WriteLine("I am waiting for somtething");
    }
    public static void Bye()
    {
        Console.WriteLine("Bye! Thanks for visiting");
    }
}
```

```C#
    Messages.Hello();
```

## Object

Object is an instance of a class
can have fields & nethods

```C#
class Human
{
    String name;
    int age;

    public void Eat()
    {
        Console.WriteLine(name + " is eating");
    }
    public void Sleep()
    {
        Console.WriteLine(name + " is sleeping");
    }
}
```

```C#
// in the main class
Human human1 = new Human()

human1.name = "Rick";
human1.age = 65;

human1.Eat();
human1.Sleep();

Human human2 = new Human()

human1.name = "Morty";
human1.age = 16;

human1.Eat();
human1.Sleep();
```

## Construtor

Constructor is a special method in a class

```C#
class Human
{
    String name;
    int age;

    public Human(String name, int age){
        this.name = name;
        this.age = age;
    }

    public void Eat()
    {
        Console.WriteLine(name + " is eating");
    }
    public void Sleep()
    {
        Console.WriteLine(name + " is sleeping");
    }
}

```
// in the main class

Human human1 = new Human("Rick",65)
Human human2 = new Human("Morty", 16)

human1.Eat();
human1.Sleep();
human2.Eat();
human2.Sleep();
```

## static

static is a modifier to declare a static member, which belongs to the class itself
rather than to any specific object

```C#
class Car
{
    String model;
    public static int numberOfCars;

    public Car(String model)
    {
        this.model = model;
        numberOfCars++;
    }
    public static void StartRace()
    {
        Console.WriteLine("The race as begun !")
    }
}
```

```C#
// in the main class

Car car1 = new Car("Mustang");
Car car2 = new Car("Corvette");
 Console.WriteLine(Car.numberOfCars);

Car.StartRace();
```

## overladed constructo

Technique to create multiple constructors, with a different set of parameters but the same name.
name + parameters = signature

```C#
class Pizza
{
    String bread;
    String sauce;
    String cheese;
    String topping;

    public Pizza(String bread,String sauce, String cheese, String topping)
    {
        this.bread = bread;
        this.sauce = sauce;
        this.cheese = cheese;
        this.topping = topping;
    }

    public Pizza(String bread,String sauce, String cheese)
    {
        this.bread = bread;
        this.sauce = sauce;
        this.cheese = cheese;
    }

    public Pizza(String bread,String sauce)
    {
        this.bread = bread;
        this.sauce = sauce;
    }

    public Pizza(String bread)
    {
        this.bread = bread;
    }

}
```

```C#
// Main

Pizza pizza = new Pizza("stuffed crust", "red sauce", "mozzarella");
Pizza pizza1 = new Pizza("stuffed crust", "red sauce");
```

## inheritance

1 or more child classes recieving fields, methods, etc. from a common parent

```C#
class Vehicle
{
    public int speed = 0
    
    public void go()
    {
        Console.WriteLine("this vehicle is moving !");
    }
}

Class Car : Vehicle
{
    public int wheels = 4;
}
Class Bicycle : Vehicle
{
    public int wheels = 2;
}
Class Boat : Vehicle
{
    public int wheels = 0;
}
```

```C#
// Main

Car car = new Car();
Bicycle bicycle = new Bicycle();
Boat boat = new Boat();

Console.WriteLine(car.speed());
Console.WriteLine(car.wheels());
Console.WriteLine(car.go());

Console.WriteLine(bicycle.speed());
Console.WriteLine(bicycle.wheels());
Console.WriteLine(bicycle.go());

Console.WriteLine(boat.speed());
Console.WriteLine(boat.wheels());
Console.WriteLine(boat.go());
```

## abstract classes

modifier that indicates missing components or incomplete implemetation

```C#
abstract class Vehicle
{
    public int speed = 0
    
    public void go()
    {
        Console.WriteLine("this vehicle is moving !");
    }
}

Class Car : Vehicle
{
    public int wheels = 4;
    int maxSpeed = 500; 
}
Class Bicycle : Vehicle
{
    public int wheels = 2;
    int maxSpeed = 50; 
}
Class Boat : Vehicle
{
    public int wheels = 0;
    int maxSpeed = 100; 
}
```

```C#
// Main
Car car = new Car();
Bicycle bicycle = new Bicycle();
Boat boat = new Boat();
Vehicle vehicle new Vehicle();
// error can't instanciate
```

## array of object

```C#
Class Car 
{
    public String model;
    public Car(String model)
    {
        this.model = model;
    }
}
```

```C#
Car[] garage = new Car[3]

Car car1 = new Car("Mustang");
Car car2 = new Car("Corvette");
Car car3 = new Car("Lambo");

garage[0] = car1
garage[1] = car2
garage[2] = car3

// or with anonymous object

Car[] garage = {new Car("Mustang"), new Car("Corvette"), new Car("Lambo")}

forach(Car car in garage)
{
    Console.WriteLine(car.model());
}
```