Explain boxing and unboxing with examples.

Question

ICSM Computer · Answer

What is Boxing and Unboxing in C#?
Boxing and Unboxing are concepts in C# related to
value types (int, bool, struct, etc.) and
reference types (object, class, etc.).
Definitions
Concept
Description
Boxing
Converting a value type to an object (or to any interface type it implements)
Unboxing
Extracting the value type from an object
Why Does It Happen?
C# treats value types and reference types differently:
Value types are stored on the stackReference types are stored on the heapTo store a value type in a variable of type object, it must be 
boxed (copied to the heap).
Example: Boxing
int number = 42;           // value type (stack)
object obj = number;       // BOXING (copy 'number' into heap)
What happens:
number is a value type.When assigned to object obj, it's boxed.A new object is created on the heap with a copy of
number.
Example: Unboxing
object obj = 42;           // boxing
int number = (int)obj;     // UNBOXING
Unboxing extracts the value type from the object.You must cast explicitly.If the object doesn't contain the expected type, it throws InvalidCastException.
Example with Error:
object obj = 42;
double num = (double)obj; // ❌ InvalidCastException
Even though both int and double are value types, the boxed
int cannot be unboxed to a double.
Performance Impact
Boxing and unboxing is relatively expensive, especially in loops.Frequent boxing/unboxing can lead to GC pressure and 
heap fragmentation.
Example with Collection
Before generics:
ArrayList list = new ArrayList();
list.Add(10);              // boxing
int x = (int)list[0];      // unboxing
With generics (avoids boxing):
Listandlt;intandgt; list = new Listandlt;intandgt;();
list.Add(10);              // no boxing
int x = list[0];           // no unboxing
Summary
Operation
Description
Explicit?
Heap/Stack
Boxing
Value → Object (value to reference)
No
Moves to heap
Unboxing
Object → Value (reference to value)
Yes
Copies to stack

Concept	Description
Boxing	Converting a value type to an object (or to any interface type it implements)
Unboxing	Extracting the value type from an object

forum

Explain boxing and unboxing with examples.

Anubhav Kumar

Can you answer this question?

1 Answers

What is Boxing and Unboxing in C#?

Definitions

Why Does It Happen?

Example: Boxing

What happens:

Example: Unboxing

Example with Error:

Performance Impact

Example with Collection

Summary

Liked By

Operation	Description	Explicit?	Heap/Stack
Boxing	Value → Object (value to reference)	No	Moves to heap
Unboxing	Object → Value (reference to value)	Yes	Copies to stack