A partial class is a class whose definition is present in two or more files. Each source file has a section of the class, and all parts are combined when the application is compiled. To split a class definition partial keyword is used as shown in the example below. person class is split into 2 parts. The first part defines the Working() method and the second part defines the Idle() method. When we compile this program both the parts will be combined and compiled. Note that both the parts uses partial keyword and public access modifier.

using System;
namespace PartialClass
{
public partial class Person
{
public void Working()
{
Console.WriteLine("I am Working");
}
}
public partial class Person
{
public void Idle()
{
Console.WriteLine("I am Idle");
}
}
public class Demo
{
public static void Main()
{
personObject = new Person();
PersonObject.Study();
PersontObject.Play();
}
}
}

The advantage of using partial classes is as follows.

When working on large projects, spreading a class over separate files enables multiple programmers to work on it at the same time.

When working with automatically generated source, code can be added to the class without having to recreate the source file.

 Visual Studio uses this approach when it creates Windows Forms, Web service wrapper code, and so on. You can create code that uses these classes without having to modify the file created by Visual Studio.

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