Boxing and Unboxing in C#

Boxing and Unboxing:

Boxing:

• Converting value type to reference Type.
• Boxing Supports Implicit and Explicit  conversion
• Boxing 20 times costlier than normal initialization, because  when ever boxing is done the following tasks will be performed instantly.
• Runtime will search for respective data with the stack
• A copy of value is made into Heap.
• Reference to this copy is maintained from the object variable.

Example:

               int i = 123;

               object o = (object)i;  // boxing

Unboxing:

• Converting reference type to value type.
• Unboxing supports Explicit conversion.
• Unboxing is 4 times costlier than normal initialized because, when unboxing is made following tasks are performed internally.
• Object referenced value is searched within the heap.
• A copy of this is made into stack.

Example:

               o = 123;

               i = (int) o; // unboxing

When to use Boxing and Unboxing :

Use only  if necessary, but we should use Boxing and Unboxing in case of other operations are costlier than Boxing and unboxing.