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Table of contents
1.
Introduction
2.
Partial Classes
3.
Key Points
4.
Advantages of using partial classes
5.
Examples
5.1.
Example 1
5.2.
Example 2
6.
Frequently Asked Questions
6.1.
What is meant by partial classes?
6.2.
In what cases do we use a partial class?
6.3.
Why do we need a partial class in C#?
7.
Conclusion
Last Updated: Mar 27, 2024

Partial Classes in C#

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Introduction

The basic concepts of Object-Oriented Programming are class and object, which focus on real-life things. A class can be defined as a blueprint or prototype used to construct objects. A class is a single element containing fields and methods in one package (member functions that specify actions). Polymorphism, inheritance, and the idea of derived classes and base classes are all supported by classes in C#. In this article, we shall be focussing on the Partial Classes in C#. 

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Partial Classes

A partial class is a feature that is specific to C#. It has the unusual ability to split a single class's function into many files, which are subsequently combined into a single class file when the application is built. The partial keyword is used to construct a partial class. This keyword may also separate method, interface, or structure functionality into various files.

Syntax

public partial Class_name
{
  //code
}
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Key Points

Before implementing partial classes, you need to keep a few key points in mind.

  • When you need to split a class, method, interface, or structure's functionality into several files, you should use the partial keyword, and all of the files must be accessible at build time to create the final file.
     
  • The partial modifier may appear only before terms like struct, class, and interface.

 

  • The partial class definition should be in the same assembly and namespace as the whole class declaration. As with the rest of the project, the source file name might differ.
     
  • Every component of the partial class definition should be accessible in the same way as private, protected, and other classes are.

 

  • If any component of a partial class is declared as abstract, sealed, or base, the entire class is declared to be of the same type.

 

  • It is also possible for the user to employ nested partial types. Although different pieces may have different base types, the final type must inherit all of them.

Advantages of using partial classes

Following are the advantages of using partial classes:

  • Multiple developers can simultaneously work on the same class in various files using partial classes.
     
  • You can read and comprehend the code by separating the UI of the design code from the business logic code using the partial class idea.
     
  • When dealing with automatically produced code, you may add it to a class without rebuilding the source file, as you would in Visual Studio.
     
  • Compressing huge classes into tiny ones can also help you maintain your application more efficiently.

Examples

Now, let us see some programming examples to understand how can we implement partial classes in C#.

Example 1

using System;
namespace HeightWeightInfo
{
    class File1
    {
    }
    public partial class Record
    {
        private int h;
        private int w;
        public Record(int h, int w)
        {
            this.h = h;
            this.w = w;
        }
    }
}
namespace HeightWeightInfo
{
    class File2
    {
    }
    public partial class Record
    {
        public void PrintRecord()
        {
            Console.WriteLine("Height:"+ h);
            Console.WriteLine("Weight:"+ w);
        }
    }
}
namespace HeightWeightInfo
{
    class Program
    {
        static void Main(string[] args)
        {
            Record myRecord = new Record(2, 4);
            myRecord.PrintRecord();
            Console.ReadLine();
        }
    }
}

Output

Height:2
Weight:4

In this example, we have used the partial class to get the height and weight of an object.

Example 2

using System;
namespace BookArticleAuthorInfo
{
    class Book1 {
}
public partial class Record{
private string a;
private int t;


public Record(string a, int t)
{
this.a = a;
this.t = t;
}
}
}
namespace BookArticleAuthorInfo
{
    class Book2{
    }
    public partial class Record 
    {
        public void GetRecord()
        {
            Console.WriteLine("Author Name: " + a);
            Console.WriteLine("Total Articles:" + t);
        }
    }
}
namespace BookArticleAuthorInfo
{
    class PartialClassesDemo
    {
        static void Main(string[] args) {
            Record BookRecord = new Record("Saalim", 60);
            BookRecord.GetRecord();
            Console.ReadLine();
        }
    }
}

Output

Author Name: Saalim
Total Articles:60

In this example, we have used the partial classes to get the total number of books written and the and the name of the author.

Frequently Asked Questions

What is meant by partial classes?

Parts of a class that the compiler can combine to make a whole class are partial classes. Although two or more partial classes can be defined in the same file, the specific purpose of a partial class is to allow a class definition to be spread across multiple files.

In what cases do we use a partial class?

The primary application of partial classes is to make the lives of code generators and designers simpler. Partial classes enable the generator to produce only the code that is required, without having to deal with user modifications to the file. Users can also annotate the class with new members by creating a second partial class. This gives a very simple foundation for concern separation.

Why do we need a partial class in C#?

A partial class is a feature that is specific to C#. It has the rare ability to split a single class's function into many files, which are subsequently combined into a single class file when the application is built.

Conclusion

In this article, we have extensively focussed on Partial classes in C#. We have briefly introduced the topic along with the idea of the topic. We also covered various vital points. We also talked about the advantages. In the end, we covered the code examples along with their output and explanation.

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