Partial Class

Partial class is a special feature of C#. It provides a special ability to split single class into multiple files and all these files are combined into a single class file when the application is compiled. A partial class is created by using a partial keyword. This keyword is also useful to split the functionality of methods, interfaces, or structure into multiple files.

Syntax
partial class className {
    //Fields and methods
}
partial class className {
    //Fields and methods
}

CODE

EG 1 . Spliting single Rectangle class into multiple partial classes.

partial class Rectangle {
    public static double length, width;
    public static double Area() {
        return length * width;
    }
}

partial class Rectangle {
    public static double height;
    public static double Volume() {
        return Area() * height;
    }
}

partial class Rectangle {
    public static double density;
    public static double Weight() {
        return Volume() * density;
    }
}

class Program {
    static void Main() {
        Rectangle.length = 5;
        Rectangle.width = 6;
        Rectangle.height = 7;
        Rectangle.density = 2.8;
        Console.WriteLine(Rectangle.Area());
        Console.WriteLine(Rectangle.Volume());
        Console.WriteLine(Rectangle.Weight());
    }
}

OUTPUT
30
210
588

CODE EXPLANATION
In the above code, we splitted single rectangle class into 3 partial rectangle classes. It may seem like 3 different classes but it is not. Writing all those code inside single class or writing it in 3 partial classes both are same. All partial class files are combined into a single class file when we compile the program.


Where to use Partial class?
The main advantage of using partial class is the readability and maintainability of the codes. It is easier to maintain, understand, and develop a partial class than a huge class for the whole program. And also while using this partial class more developers can work simultaneously on the same project.