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Difference between Boxing and unboxing?

Posted By :Narayanan     Posted Date :November 22, 2011    Points :40   Category :C# 
Boxing: Convert value type to reference type.
UnBoxing:Convert Reference type to value Type.


You can also find related Interview Question to Difference between Boxing and unboxing?  below: 

Difference between Boxing and unboxing?

  
Boxing: Convert value type to reference type.
UnBoxing:Convert Reference type to value Type. (More...)

What is concept of Boxing and Unboxing ?

  
Boxing permits any value type to be implicitly converted to type object or to any interface type implemented by value type. Boxing is a process in which object instances are created and copy values in to that instance. Unboxing is vice versa of boxing operation where the value is copied from the instance in to appropriate storage location. Below is sample code of boxing and unboxing where integer data type is converted in to object and then vice versa.
Dim x As Integer
Dim y As Object x = 10
' boxing process
y = x
' unboxing process
x = y (More...)

What is boxing and unboxing?

  
Converting a value type to reference type is called Boxing and Converting reference type of value type is Unboxing.

int i = 1;
object o = i; // boxing
int j = (int) o; // unboxing (More...)

What is boxing and unboxing explain with example?

  
The example

class Test
{
static void Main() {
int i = 1;
object o = i; // boxing
int j = (int) o; // unboxing
}
}

An int value can be converted to object and back again to int.
This example shows both boxing and unboxing. When a variable of a value type needs to be converted to a reference type, an object box is allocated to hold the value, and the value is copied into the box.

Unboxing is just the opposite. When an object box is cast back to its original value type, the value is copied out of the box and into the appropriate storage location. (More...)

What is boxing and unboxing?

  
Boxing is the process in which a object instances created and copying value type values to it. Unboxing is vice versa of boxing operation in which the value is copied from the instance into appropriate storage location. (More...)

What is Boxing and unboxing ?

  
Boxing:
The conversion of a value type instance to an object, which implies that the instance will carry full type information at run time and will be allocated in the heap. The Microsoft intermediate language (MSIL) instruction set's box instruction converts a value type to an object by making a copy of the value type and embedding it in a newly allocated object.

Un-Boxing:
The conversion of an object instance to a value type.
(More...)

What is concept of Boxing and Unboxing?

  
Boxing permits any value type to be implicitly converted to type object or to any interface type
implemented by value type. Boxing is a process in which object instances are created and copy
values in to that instance.

Unboxing is vice versa of boxing operation where the value is copied from the instance in to
appropriate storage location. (More...)

What is boxing and unboxing?

  
==Boxing
Value type to object type. Allocates memory on Heap.

==UnBoxing
Object type to value type. Allocates memory on Stack.
(More...)

What is boxing and unboxing ?

  

he operation of Converting a Value Type to a Reference Type is called Boxing
Boxing Example:

int Var = 1; //This is a value type

Object Obj = Var; //Boxing we assign a value type into a reference

An unboxing conversion permits an explicit conversion from type object to any value-type

int Var = 1;

Object Obj = Var; //Boxing

int i = (int)Obj; //Unboxing (More...)

Difference Between Delete and Truncate

  
.Delete table is a logged operation, so the deletion of each row gets logged in the transaction log, which makes it slow.

. Truncate table also deletes all the rows in a table, but it won't log the deletion of each row, instead it logs the de-allocation of the data pages of the table, which makes it faster. Of course, truncate table cannot be rolled back.

. Truncate table is functionally identical to delete statement with no "where clause" both remove all rows in the table. But truncate table is faster and uses fewer system and transaction log resources than delete.

. Truncate table removes all rows from a table, but the table structure and its columns, constraints, indexes etc., remains as it is.

. In truncate table the counter used by an identity column for new rows is reset to the seed for the column.

. If you want to retain the identity counter, use delete statement instead.

. If you want to remove table definition and its data, use the drop table statement.

. You cannot use truncate table on a table referenced by a foreign key constraint; instead, use delete statement without a where clause. Because truncate table is not logged, it cannot activate a trigger.

. Truncate table may not be used on tables participating in an indexed view. (More...)

Difference between assembly manifest & metadata?

  
assembly manifest - An integral part of every assembly that renders the assembly self-describing. The assembly manifest contains the assembly's metadata. The manifest establishes the assembly identity, specifies the files that make up the assembly implementation, specifies the types and resources that make up the assembly, itemizes the compile-time dependencies on other assemblies, and specifies the set of permissions required for the assembly to run properly. This information is used at run time to resolve references, enforce version binding policy, and validate the integrity of loaded assemblies. The self-describing nature of assemblies also helps makes zero-impact install and XCOPY deployment feasible.

metadata - Information that describes every element managed by the common language runtime: an assembly, loadable file, type, method, and so on. This can include information required for debugging and garbage collection, as well as security attributes, marshaling data, extended class and member definitions, version binding, and other information required by the runtime. (More...)

What is the difference between ref & out parameters?

  
An argument passed to a ref parameter must first be initialized. Compare this to an out parameter, whose argument does not have to be explicitly initialized before being passed to an out parameter. (More...)

What is the difference between a Struct and a Class?

  
The struct type is suitable for representing lightweight objects such as Point, Rectangle, and Color. Although it is possible to represent a point as a class, a struct is more efficient in some scenarios. For example, if you declare an array of 1000 Point objects, you will allocate additional memory for referencing each object. In this case, the struct is less expensive.

When you create a struct object using the new operator, it gets created and the appropriate constructor is called. Unlike classes, structs can be instantiated without using the new operator. If you do not use new, the fields will remain unassigned and the object cannot be used until all of the fields are initialized.

It is an error to declare a default (parameterless) constructor for a struct. A default constructor is always provided to initialize the struct members to their default values.

It is an error to initialize an instance field in a struct.

There is no inheritance for structs as there is for classes. A struct cannot inherit from another struct or class, and it cannot be the base of a class. Structs, however, inherit from the base class Object. A struct can implement interfaces, and it does that exactly as classes do.

A struct is a value type, while a class is a reference type. (More...)

Difference between type constructor and instance constructor? What is static constructor, when it will be fired? And what is its use?

  
(Class constructor method is also known as type constructor or type initializer)
Instance constructor is executed when a new instance of type is created and the class constructor is executed after the type is loaded and before any one of the type members is accessed. (It will get executed only 1st time, when we call any static methods/fields in the same class.) Class constructors are used for static field initialization. Only one class constructor per type is permitted, and it cannot use the vararg (variable argument) calling convention. (More...)

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