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Showing posts with label boxing and unboxing in asp.net. Show all posts
Showing posts with label boxing and unboxing in asp.net. Show all posts

Friday, 28 June 2013

boxing and unboxing in c#

boxing and unboxing in c#
Boxing :-

  means converting value-type to reference-type.

Eg:

int I = 20;

string s = I.ToSting();

UnBoxing :- 
 means converting reference-type to value-type.

Eg:

int I = 20;

string s = I.ToString(); //Box the int

int J = Convert.ToInt32(s); //UnBox it back to an int.


Note: Performance Overheads due to boxing and unboxing as the boxing makes a copy of value type from stack and place it inside an object of type System.Object in the heap.

Value Type :-
As name suggest Value Type stores “value” directly.
For eg: 


//I and J are both of type int
I = 20;
J = I;

int is a value type, which means that the above statements will results in two locations in memory.
For each instance of value type separate memory is allocated.Stored in a Stack.
It Provides Quick Access, because of value located on stack.
 Reference Type : -

As name suggest Reference Type stores “reference” to the value.
For eg: 


Vector X, Y; //Object is defined. (No memory is allocated.)
X = new Vector(); //Memory is allocated to Object. //(new is responsible for allocating memory.)
X.value = 40; //Initialising value field in a vector class.
Y = X; //Both X and Y points to same memory location. //No memory is created for Y.
Console.writeline(Y.value); //displays 40, as both points to same memory
Y.value = 60;
Console.writeline(X.value); //displays 60.
Note: If a variable is reference it is possible to indicate that it does not refer to any object by setting its value to null;

Reference type are stored on Heap.
It provides comparatively slower access, as value located on heap.

 

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