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LESSON : Boxing & Un-Boxing

C# has a number of features; in this lesson, we are going to discuss about a special feature called “Boxing & Un-Boxing”.

First we’ll see about what is meant by “Boxing”

Boxing is nothing but converting a value type object to reference type object.

When a variable of value type needs to be converted to reference type, an object box is allocated to hold the value; and the value is copied into that box. This process of copying a value to a box is called Boxing.

Analogy: It’s similar to that process of transferring data from a Floppy disk to our PC .Likewise in boxing it is possible to convert a value type object to reference type object.

Un-Boxing:

Un-Boxing is the reverse process of Boxing i.e. converting reference type back to the value type is known as Un-Boxing.

When an object box is cast back to its original value type, the value is copied out of that box into the appropriate storage location.

For example: Similar to re – transferring the data from our PC to a Floppy disk Drive reconverting like wise un-boxing will convert reference type into value type objects.

Here’s a sample program which gives you a better understanding.

using System;

class Boxing

{

            static void Main()

            {

                        int a = 123;    //variable declarations

                        object box = a;   // boxing

                        Console.WriteLine("Value of Boxed Object  {0}",box);            //printing the value here

                        int b = (int) box;             // unboxing

                        Console.WriteLine(“Value of Un-Boxed Object {0}”,b);   //printing the converted value here

                        Console.ReadLine();

            }

}

In the sample program, we have used both the boxing and un-boxing features.

This line is very much familiar to us. Let’s declare a namespace “System” here.

Then we are creating a class namely “Boxing”.

In the main method, we declare a variable namely “a” with integer type. And we have also assigned the value of “a” is equal to “123”.

Now, we are going to box the value “123”. For that, we are creating an object namely “box” and we also assign the variable ‘a’ to the box object. The value of “a” is transferred to the object “box” while compiling this line.

Here, we can verify the content in the object box using “Write line” method.

Next, we are un-boxing the content of the object “box” and stored it in the variable “b”.

When the compiler compiles this line, object “box” content will be transferred to “b”.

To verify the content in “b” also we can use the Write line method.

Save the application with .cs extension.

Let’s save it as “boxing.cs”

Well, now we build our application.

In Visual Studio .NET command prompt, type file name with extension; then press enter

Let’s type the name as “boxing.cs”

Here’s our file successfully executed. Open “exe” file to check output.

This line “Value of Boxed Object” is “123” which indicates that we have boxed the value.

And “Value of Un-Boxed Object” is “123” which indicates that we have un-boxed the boxed value.

This lesson ends up with “Boxing & Un-Boxing”. I hope you are clear with this concept. In the next lesson, we will discuss some more interesting topics.

plz help me to help others

Hi experts of C# - am karthi from worlds northeast team. Our team goal is to give software knowledge to all layperson around the world. We are developing content for all leading softwares, am in C# domain. Plz help me to help others.

here i posted my lesson list, plz check out this and give your valuable comments..........

C#.NET 2003

Chapter 1 Author Mentoring

1 Audience - Who can learn?

2 Employment Opportunities and Job Roles

3 Prerequisite Knowledge and Skills

4 Inspire

Chapter 2 Fundamentals of C#

5 History of C#

6 What is C#?

7 Why C#?

8 Course Objective

Chapter 3 Setting up an Environment

9 Hardware/Software Requirements

10 Installation Process

11 Trouble Shooting

Chapter 4 Introduction

12 About .NET Framework

13 Architecture of .NET Framework

14 Common Language Runtime(CLR)

15 Working of CLR

16 Just-In-Time Compiler.

17 Cross-Language Interoperability

18 Garbage Collection

19 Common Type System(CTS)

20 Common Language Specification(CLS)

21 My First C# program

Chapter 5 Window Forms & Windows Application

22 Introduction to Visual Studio

23 Visual Studio .Net IDE

24 Menus & Tool Box

25 Type’s of Windows in Visual C#

26 Creating a Windows Application

27 Understanding the code

Chapter 6 C# Fundamental

28 Data types

29 Boxing & Un-Boxing

30 Variables

31 Strings

32 Constants

33 Flow Control of Conditional Statements

34 Jumping Statement

35 Loop in C#

36 Simple Program using Statements

37 Structures & Pre-processors

38 Operators

39 Operator Overloading

Chapter 7 Programming Fundamental

40 Classes and Objects

41 Fields & Properties

42 Methods

43 Delegates & Events

44 Arrays & Indexers

45 Namespaces

46 Assemblies

47 Constructors & Destructors

48 Exception Handling

49 Threading

Chapter 8 Object-Oriented Programming

50 Principles of Object-Oriented Programming

51 Inheritance

52 Polymorphism

53 Encapsulation

54 Interfaces

Chapter 9 Data Access in ADO.NET

55 Introduction to ADO.NET

56 Different Component Of ADO.NET

57 Review of basic SQL Queries

58 Defining a Connection

59 Connecting Database using ADO.NET

60 Defining the Data adapter

61 Manipulating the Record

62 Using Stored Procedure with ADO.NET

Chapter 10 Web forms, Web controls & Web services

63 Creating and Running a Simple Web Form

64 Introduction to Web service

65 Creating a Web Service

66 Securing Web Application