What is Boxing and Unboxing in C#?

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Ashutosh Kumar Verma · Answer

C# Boxing and Unboxing
In C#, boxing and unboxing are two related concepts related to treating values ​​and expressions. Understanding these concepts is important for effective memory management and optimal performance in .NET applications.
Boxing
Boxing is the process of converting a value type (such as int, float, struct, etc.) to a reference type (specifically, an object). Create an object on this heap and copy the value to this other object.
Syntax-and 
int num = 123;    // Value type
object obj = num; // Boxing
Here is, the integer num is boxed into an object obj.
and 
Unboxing
Unboxing is the opposite of boxing. This involves converting the boxed product back to its corresponding value. This requires an explicit cast and of course copying the value back to a variable value type.
Syntax-and 
object obj = 123;   // Boxing
int num = (int)obj; // Unboxing
Here is, The object obj unboxed into an integer num
Example-and 
using System;
namespace myProgram{
	class Program
	{
		 public static void Main()
 		{
 			 // Boxing value
 			 int num = 42;
 			 object obj = num; // num is boxed into obj
  			Console.WriteLine("Boxed value: " + obj);
  			// Unboxing value
  			int unboxedNum = (int)obj; // obj is unboxed back to an int
  			Console.WriteLine("Unboxed value: " + unboxedNum);
 		}
	}
}
Output-and 
Boxed value: 42
Unboxed value: 42
Key Points
Boxing
Conversion implicitlyThis includes creating objects on the heap.There may be performance overhead due to memory allocation and garbage collection.
Unboxing
Conversion explicitlyIt may throw an InvalidCastException if the object does not have a valid target type.
Performance Considerations
Boxing unboxing can have important business implications because,
Boxing heaps allocates memory, which is costly in terms of performance compared to stack allocation.Frequent boxing and unboxing can increase garbage collection, affecting application performance.
and 
Avoiding Boxing and Unboxing
Consider the following methods to avoid unnecessary boxing and unboxing,
Use regular collections of objects (such as Listandlt;T>, 
Dictionaryandlt;TKey, TValue>) instead of irregular objects (such as 
ArrayList, Hashtable, etc.) to avoid value type boxing.Reduce the use of object type variables for storing values ​​unless absolutely necessary.
and 
By carefully understanding and managing boxing and unboxing, you can write more efficient and better-performing C# code.
and 
Also, Read: How to sort object arrays by specific property in C#?

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What is Boxing and Unboxing in C#?

Revati S Misra

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1 Answers

C# Boxing and Unboxing

Boxing

Unboxing

Key Points

Performance Considerations

Avoiding Boxing and Unboxing

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