A Partial class is one that can be split among multiple physical files. This feature was introduced with the release of C# version 2.0. With C#, we can split the source code for a class into separate files so that we can organize the definition of a large class into smaller, easier to manage pieces. When we split a class across multiple files, we define the parts of the class by using the partial keyword in each file. Each file contains a section of the class definition, and all parts are combined when the application is compiled.

Example

using System;
 
namespace PartialClassConsoleApplication
{
    public partial class Add
    {
        int x, y;
        public void getvalue(int x, int y)
        {
            this.x= x;
            this.y= y;
        }
    }
    public partial class Add
    {
        public void add()
        {
            Console.WriteLine("Addition of "+ x + " & "+ y + " = "+ (x + y));
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Add aobj = new Add();
            aobj.getvalue(4, 6);
            aobj.add();
        }
    }
}

Output:-

Addition of 4 & 6 = 10

In this example, I’ve created a class named Add and split it into two parts with partial keyword. In one part , declared two variables x, y and assign value to them through function getvalue() and in other part created a function named add() who add the values of x and y and print the values.