Boxing and Unboxing in .NET

Menaka Priyadharshini B

10y1.2kLearn iOS Programming

Am looking for the exact answer to find out in what way that boxing and unBoxing are used in .NET

4 Replies

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Tapan Patel10y ago
Accepted answer
If you know the difference between stack and heap à any variable (of primitive data types like int , bool, double and so on ) gets stored on the stack where as any object is stored on the different data structure of the memory called heap.

Consider below example.
int t=5;
bool isValid=false;
TempClass tempObj=new TempClass();//classTempClass{intx;inty;}
If you look at statement for int and bool, CLR allocates memory on the stack.
When it comes to initialize TempClass referece, it allocates the reference (tempObj) on the stack. But it won’t allocate memory yet. But when it encounters new keyword, it allocates the memory on the Heap and the first byte’s address gets stored on the stack reference (in tempObj). So as it is supposed to store the underlying datatypes on heap, CLR internally uses boxing to store them on the Heap as they represent the complete object and not the primitive type.

So if you do something (a standard example) like this:
int i =5;

object o=i; //this makes compiler to move the int i from stack to Heap with boxing (converting it to object type)
That is why it is advisable not to use Int or Boolean , instead use int, bool so that you will save some time that makes CLR to move code from stack to Heap. So bottom line is , if you don't need it, don't use it as it causes performance hits.

Please mark it as an answer if addresses the issue.
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Menaka Priyadharshini B10y ago
Thankz a lotz krishna for giving such a brief explanation
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Krishna Rajput Singh10y ago
Hello Menaka thank you for writing below links i hope helpful for you.........:)
https://msdn.microsoft.com/en-IN/library/yz2be5wk.aspx
http://csharp.net-informations.com/language/csharp-boxing-unboxing.htm

http://www.codeproject.com/Articles/2225/Boxing-and-unboxing-in-C
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Midhun Tp10y ago
Hi,
Boxing is the implicit conversion of a value type(int,char,etc.) to a reference type(object).
Unboxing is the explicit conversion of same reference type back to value type.
inti=10;
ArrayListarrlst=newArrayList();
//ArrayListcontainsobjecttypevalue
//So,intiisbeingcreatedonheap
arrlst.Add(i);//Boxingoccursautomatically
intj=(int)arrlst[0];//Unboxingoccurs
Please check below links for simple explanation and samples-
http://csharp.net-informations.com/language/csharp-boxing-unboxing.htm
http://www.c-sharpcorner.com/uploadfile/2072a9/boxing-and-unboxing-in-c-sharp/
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