ASP.Net and ASP.Net MVC Tutorial: August 2013

.Net Interview Questions and Answers Volume-III

What is the difference between Overloading and Shadowing?

Overloading : A Member has the name, but something else in the signature is different.
Shadowing : A member shadows another member if the derived member replaces the base member

What is the difference between Overloading and Overriding?

Overloading : Method name remains the same with different signatures.
Overriding : Method name and Signatures must be the same.

what is Boxing and Unboxing?

Boxing is an implicit conversion of a value type to the type object
int i = 123; // A value type
Object box = i // Boxing
--------------------------------------------------------------------------------
Unboxing is an explicit conversion from the type object to a value type
int i = 123; // A value type
Object box = i; // Boxing
int j = (int)box; // Unboxing

what is the difference between array and arraylist?

Arrays are always fixed size in nature and ArrayList can grow dynamically.

what is the difference between readonly and constant varaibles??

readonly - variables are dynamic constant, you can modify the value in the constructor only.
constant - variables are constant, you cannot change the values once its declared as a constant.

What is enum?

An enum type is a distinct type that declares a set of named constants.They are strongly typed constants. They are unique types that allow to declare symbolic names to integral values.
public enum Grade {
A,
B,
C
}

What is the life cycle for an object?

1. The object is created.
2. Memory is allocated for the object.
3. The constructor is run.
4. The object is now live.
5. if the object is no longer in use, it needs finalization.
6. Finalizers are run.
7. The object is now inaccessible and is available for the garbage collector to carry out clean-up.
8. The garbage collector frees up associated memory.

What is CodeDOM?

 CodeDOMis an object model, which is used to generate a source code. It is designed to be language independent - once you create a CodeDom hierarchy for a program we can then generate the source code in any .NET complaint language.

What is Static class?

1.A static class can only contain static members.
2.We cannot create an instance of a static class.
3.Static class is always sealed and they cannot contain instance constructor
4.Hence we can also say that creating a static class is nearly same as creating a class with only static members and a private constructor (private constructor prevents the class from being instantiated).
---Good example is the System.Math class

What are method parameters in C#?

C# is having 4 parameter types which are
1.Value Parameter. default parameter type. Only Input
2.Reference(ref) Parameter. Input\Output
3.Output(out) Parameter.
4.Parameter(params) Arrays

How to get the Assembly version programatically?

System.Reflection.AssemblyName myAssemblyName = System.Reflection.AssemblyName.GetAssemblyName(@"D:\SepTest\Bin\Ajax.dll");
MessageBox.Show(myAssemblyName.Version.ToString());

What is delay signing?

Delay signing allows you to place a shared assembly in the GAC by signing the assembly with just the public key. This allows the assembly to be signed with the private key at a later stage, when the development process is complete and the component or assembly is ready to be deployed.

What is partial class?

- The partial classes use the new keyword partial and are defined in the same namespace.
- partial classes as a class definition split across many files for convenience
- Partial classes must use the same access modifier (for example Public Protected and Private).
- If any single part is abstract (MustInherit), the whole class is abstract.
- If any parts are sealed (NotInheritable), the whole class is sealed.
- If any part declares a base type, the whole class inherits that base type.
- Parts can specify different interfaces, but the whole class implements all interfaces.
- Delegates and enumerations cannot use the partial modifier.

What is Generics in C#?

Parametric Polymorphism is a well-established programming language feature. Generics offers this feature to C#.
The concept is very close to Templates in C++.
In the generic List<T> collection, in System.Collections.Generic namespace, the same operation of adding items to the collection looks like this:

// The .NET Framework 2.0 way of creating a list

List<int> list1 = new List<int>();

list1.Add(3); // No boxing, no casting

list1.Add("First item"); // Compile-time error

What is Anonymous method in C#(.NET 2.0)?

Anonymous methods is a new feature in C# 2.0 that lets you define an anonymous (that is, nameless) method called by a delegate.

For example, the following is a conventional SomeMethod method definition and delegate invocation:

class SomeClass

{

delegate void SomeDelegate();

public void InvokeMethod()

{

SomeDelegate del = new SomeDelegate(SomeMethod);

del();

}

void SomeMethod()

{

MessageBox.Show("Hello");

}

You can define and implement this with an anonymous method:

class SomeClass

{

delegate void SomeDelegate();

public void InvokeMethod()

{

SomeDelegate del = delegate()

{

MessageBox.Show("Hello");

};

del();

}

The anonymous method is defined in-line and not as a member method of any class. Additionally, there is no way to apply method attributes to an anonymous method, nor can the anonymous method define generic types or add generic constraints.

Anonymous methods can be used anywhere that a delegate type is expected. You can pass an anonymous method into any method that accepts the appropriate delegate type as a parameter:

what are the different levels Thread priority provided by .NET?

- ThreadPriority.Highest
- ThreadPriority.AboveNormal
- ThreadPriority.Normal
- ThreadPriority.BelowNormal
- ThreadPriority.Lowest
We can change the thread priority setting by
Threadname.Priority=ThreadPriority.Highest

What is event bubbling?

Server Controls like datagrid, Datalist, Repeater can have child controls inside them.For example Combo box inside datagrid. The Child controls(combo box) send their events to parent(datagrid) is known as event bubbling.

what are the serialization types supported in .NET?

Serialization is the process of saving the state of an object by converting it to a stream of bytes. The object can then be persisted to file, database, or even memory. The reverse process of serialization is known as deserialization.
The serialization types are as follows
1. XML serialization
2. Binary serialization
3. Soap serialization.
Code snippet for XML serialization

System.Xml.Serialization.XmlSerializer xs = new System.Xml.Serialization.XmlSerializer(typeof(Employee));
FileStream OutputFS = new FileStream(@"C:\output.xml",FileMode.Create);
xs.Serialize(OutputFS, emp);

Code snippet for Binary serialization

System.Runtime.Serialization.Formatters.Binary.BinaryFormatter bf = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
FileStream OutputFS = new FileStream(@"C:\output.bin", FileMode.Create);
bf.Serialize(OutputFS, emp);

Code snippet for Soap serialization

System.Runtime.Serialization.Formatters.Soap.SoapFormatter sf = new System.Runtime.Serialization.Formatters.Soap.SoapFormatter();
FileStream OutputFS = new FileStream(@"C:\output.soap", FileMode.Create);
sf.Serialize(OutputFS, emp);

What is Array?

Example of Single Dimension Array in .Net
int [] intArray = new int[3];
intArray[2] = 22; // set the third element to 22

Example of Multi Dimension Array in .Net
int [][] myTable = new int[2,3];
myTable[1,2] = 22;

Example of Jagged Array in .Net : Variable Length Array in .Net
int [][] myTable = new int[3][];
myTable[0] = new int[5];
myTable[1] = new int[2];
myTable[2] = new int[4];
myTable[0][2] = 11;

Example of String Array in .Net
string []names = new string[4];
names[2] = “God will make me win”;

Limitation of Arrays
-->The size of an array is always fixed and must be defined at the time of instantiation of an array.
-->Secondly, an array can only contain objects of the same data type, which we need to define at the time of its instantiation.

What is Nullable Type in .Net 2.0?

Nullable in .Net 2.0, helps to determine whether variable has been assigned a value or not. Example: Quiz application having option yes/no, but it should displayed “Not Attempted” when user does not make any choice.
Syntax :
Nullable b = null
//only for C#
bool? b = null;

Example :
if (b.HasValue)
Console.WriteLine("User has Attempted Given Question");
else
Console.WriteLine("User has not Attempted Given Question");

What is the difference between out and ref parameter?

Difference is that out parameters need to be declared but not initialized.
ref parameter will have a value even before the method call..

what is the Concept of heap and stack?

Local Variables	Stack
Free Memory (Larger Memory Area than Stack).	Heap
Global Variables	Permanent Storage area
Program Instruction

what are value types and reference types?

Value type	Reference type
1. Value types are stored in the Stack	1. Reference types are stored in the Heap
2. Eg. bool, byte,char, decimal,double,enum, float, int, long, sbyte, short, strut, uint, ulong, ushort	2. Eg. class, delegate, interface, object, string

What are primitive data types?

Primitive data types are basic data types. C# is having 15 primitive data types
Value types - 13
boolean, byte, char, double, decimal, float, int, long, short, sbyte, ushort, uint, ulong
Ref types - 2
string and object

what are the differences between string and stringbuilder?

System.string	System.Text.StringBuilder
1.Reference type ie stored in the heap	1.Reference type ie stored in the heap.
2. Immutable, Once the string object is created, its length and content cannot be modified.	2. Mutable, Even after object is created, it can be able to modify length and content.
3. Slower	3. Faster
4. Eg // This method will create almost 100000 String instances String s = "MyName"; for( int i=0; i<100000; ++i) s+=i.ToString();	4. Eg // This will use only one instance and will allocate the space needed for each append, efficiently. Much much better.. StringBuilder sb = new StringBuilder(s); for( int i=0; i<100000; ++i) sb.Append(i.ToString());

what is the difference between Manifest and Metadata?

Manifest	Metadata
1. Manifest describes assembly itself	1. Metadata describes contents in an assembly
2. Assembly name, Version number, Culture, Strong name, list of all files, Type references and referenced assemblies	2. classes, interfaces, enums, structs, etc., and their containing namespaces, the name of each type, its visibility/scope, its base class, the interfaces it implemented, its methods and their scope, and each method’s parameters, type’s properties, and so on

what is the difference between abstract class and interface?

Abstract Classes	Interfaces
Abstract classes are incomplete classes	Interfaces are used to define specifications
can have concrete methods	cannot have concrete methods
used to achieve polymorphism	used to achieve multiple inheritance
members can have access modifiers(public, abstract, virtual, private, internal)	members access modifiers are public by default(can not declare explicitly)

What are the access modifiers in C#

There are Four access modifiers
public : Members are fully accessible
protected : A protected member is accessible from within the class in which it is declared
internal : Internal members are accessible only within files in the same assembly
private : Private members are accessible only within the body of the class

What are the Accessibility levels in C#

There are five Accessibility levels
public : Access is not restricted.
protected : Access is limited to the containing class or types derived from the containing class.
internal : Access is limited to the current assembly. protected internal : Access is limited to the current assembly or types derived from the containing class.
private : Access is limited to the containing type.

What is Dispose method in .NET?

.NET provides "Finalize" method in which we can clean up our resources. But relying on this is not always good so the best is to implement "IDisposable" interface and implement the "Dispose" method where you can put your clean up routines

What is CLR??

The CLR(Common Language Runtime) Responsibilities are
√ Garbage Collection
√ Code Access Security
√ Code Verification
√ IL( Intermediate language )-to-native translators and optimizer’s

What is CAS?

.NET has two kinds of security:
--Role Based Security
--Code Access Security
======================

CAS is the CLR's security system that enforces security policies by preventing unauthorized access to protected resources and operations. Using the Code Access Security, you can do the following:
-Restrict what your code can do
-Restrict which code can call your code

Code access security consists of the following elements:
permissions - FileIOPermission (when working with files), UIPermission (permission to use a user interface), SecurityPermission (this is needed to execute the code.
permission sets - FullTrust, LocalIntranet, Internet, Execution and Nothing are some of the built in permission sets in .NET Framework
code groups - My_Computer_Zone, LocalIntranet_Zone, Internet_Zone
policy - There are four policy levels - Enterprise, Machine, User and Application Domain
We can acheieve CAS in two ways :
from the .NET Configuration Tool or from the command prompt using caspol.exe. First we'll do this using the .NET Configuration Tool. Go to Control Panel --> Administrative Tools --> Microsoft .NET Framework Configuration

What are the Garbage collector Responsiblities in .NET?

GC take the responsibility of tracking memory usage.
The .NET garbage collector is optimized for the following assumptions

1. Objects that were recently allocated are most likely to be freed.
2. Objects that have lived the longest are least likely to be become free.
3. Objects allocated together are often used together.
The objects allocated are categorized into three generations.

Most recently allocated objects are placed in generation 0.
Objects in generation 0, that survive a garbage collection pass are moved to generation 1.
generation 2 contains long-lived objects, that survive after the two collection passes.

What is the difference between Indexers and Properties?

1. An indexer is identified by it's signature. But a property is identified it's name.
2. An indexer is always an instance member, but a property can be static also.
3. An indexer is accessed through an element access. But a property is through a member access.

What is thread pooling?

You can hook up methods to the ThreadPool by using QueueUserWorkItem.
You have your method you want to run on the threads, and you must hook it up to QueueUserWorkItem.
How can you do this? You must use WaitCallback.
At MSDN, WaitCallback is described as a delegate callback method to be called when the ThreadPool executes.
It is a delegate that "calls back" its argument.
Use WaitCallback
In this part, we see that you can use WaitCallback by simply specifying the "new WaitCallback"
syntax as the first argument to ThreadPool.QueueUserWorkItem. You don't need any other code here.
void Example()
{
// Hook up the ProcessFile method to the ThreadPool.
// Note: 'a' is an argument name. Read more on arguments.
ThreadPool.QueueUserWorkItem(new WaitCallback(ProcessFile), a);
}

private void ProcessFile(object a)
{
// I was hooked up to the ThreadPool by WaitCallback.

}

What is early and late binding?

Everything is early bound in C# unless you go through the Reflection interface.
Most script languages use late binding, and compiled languages use early binding.
Early bound just means the target method is found at compile time.
Late bound means the target method is looked up at run time
Binding usually has an effect on performance. Because late binding requires lookups at runtime, it is usually means method calls are slower than early bound method calls.

What is Extension methods C#?

Extension methods enable you to "add" methods to existing types without creating a new derived type, recompiling, or otherwise modifying the original type.
An extension method is a static method of a static class, where the this modifier is applied to the first parameter. The type of the first parameter will be the type that is extended.

namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
int x = 3;
Console.WriteLine(x.factorial());
Console.ReadLine();
}
}
public static class MyMathExtension
{
public static int factorial(this int x)
{
if (x <= 1) return 1;
if (x == 2) return 2;
else
return x * factorial(x - 1);
}
}
}

What is encapsulation in C#?

Encapsulation means to wrapping up the data and methods into single unit.
C# provides accessor methods (get and set methods) which are used to achieve the encapsulation in the C#.
we can hide the data by making the access modifier private:

Encapsulation provides a way to protect data from accidental corruption. Rather than defining the data in the form of public, we can declare those fields as private
The Two ways we can acheive encapsulation by

ENCAPSULATION USING ACCESSORS(Get method) AND MUTATORS(Set method) <\li>
ENCAPSULATION USING PROPERTIES:(READ ONLY, WRITE ONLY)

What is the difference between arraylist and Generics C#?

By creating a generic class, you can create a collection that is type-safe at compile-time.
Any reference or value type that is added to an ArrayList is implicitly upcast to Object.
If the items are value types, they must be boxed when added to the list, and unboxed when they are retrieved.

Both the casting and the boxing and unboxing operations degrade performance
The other limitation is lack of compile-time type checking;

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Other Interview Questions

Short Answer .NET Interview Questions (PAGE 1)

Q1. Explain the differences between Server-side and Client-side code?
Ans. Server side code will execute at server (where the website is hosted) end, & all the business logic will execute at server end where as client side code will execute at client side (usually written in javascript, vbscript, jscript) at browser end.

Q2. What type of code (server or client) is found in a Code-Behind class?
Ans. Server side code.

Q3. How to make sure that value is entered in an asp:Textbox control?
Ans. Use a RequiredFieldValidator control.

Q4. Which property of a validation control is used to associate it with a server control on that page?
Ans. ControlToValidate property.

Q5. How would you implement inheritance using VB.NET & C#?
Ans. C# Derived Class : Baseclass
VB.NEt : Derived Class Inherits Baseclass

Q6. Which method is invoked on the DataAdapter control to load the generated dataset with data?
Ans. Fill() method.

Q7. What method is used to explicitly kill a user's session?
Ans. Session.Abandon()

Q8. What property within the asp:gridview control is changed to bind columns manually?
Ans. Autogenerated columns is set to false

Q9. Which method is used to redirect the user to another page without performing a round trip to the client?
Ans. Server.Transfer method.

Q10. How do we use different versions of private assemblies in same application without re-build?
Ans.Inside the Assemblyinfo.cs or Assemblyinfo.vb file, we need to specify assembly version.
assembly: AssemblyVersion

Q11. Is it possible to debug java-script in .NET IDE? If yes, how?
Ans. Yes, simply write "debugger" statement at the point where the breakpoint needs to be set within the javascript code and also enable javascript debugging in the browser property settings.

Q12. How many ways can we maintain the state of a page?
Ans. 1. Client Side - Query string, hidden variables, viewstate, cookies
2. Server side - application , cache, context, session, database

Q13. What is the use of a multicast delegate?
Ans. A multicast delegate may be used to call more than one method.

Q14. What is the use of a private constructor?
Ans. A private constructor may be used to prevent the creation of an instance for a class.

Q15. What is the use of Singleton pattern?
Ans. A Singleton pattern .is used to make sure that only one instance of a class exists.

Q16. When do we use a DOM parser and when do we use a SAX parser?
Ans. The DOM Approach is useful for small documents in which the program needs to process a large portion of the document whereas the SAX approach is useful for large documents in which the program only needs to process a small portion of the document.

Q17. Will the finally block be executed if an exception has not occurred?
Ans.Yes it will execute.

Q18. What is a Dataset?
Ans. A dataset is an in memory database kindof object that can hold database information in a disconnected environment.

Q19. Is XML a case-sensitive markup language?
Ans. Yes.

Q20. What is an .ashx file?
Ans. It is a web handler file that produces output to be consumed by an xml consumer client (rather than a browser).

Short Answer .NET Interview Questions (PAGE 2)

Q21. What is encapsulation?
Ans. Encapsulation is the OOPs concept of binding the attributes and behaviors in a class, hiding the implementation of the class and exposing the functionality.

Q22. What is Overloading?
Ans. When we add a new method with the same name in a same/derived class but with different number/types of parameters, the concept is called overluoad and this ultimately implements Polymorphism.

Q23. What is Overriding?
Ans. When we need to provide different implementation in a child class than the one provided by base class, we define the same method with same signatures in the child class and this is called overriding.

Q24. What is a Delegate?
Ans. A delegate is a strongly typed function pointer object that encapsulates a reference to a method, and so the function that needs to be invoked may be called at runtime.

Q25. Is String a Reference Type or Value Type in .NET?
Ans. String is a Reference Type object.

Q26. What is a Satellite Assembly?
Ans. Satellite assemblies contain resource files corresponding to a locale (Culture + Language) and these assemblies are used in deploying an application globally for different languages.

Q27. What are the different types of assemblies and what is their use?
Ans. Private, Public(also called shared) and Satellite Assemblies.

Q28. Are MSIL and CIL the same thing?
Ans. Yes, CIL is the new name for MSIL.

Q29. What is the base class of all web forms?
Ans. System.Web.UI.Page

Q30. How to add a client side event to a server control?
Ans. Example... BtnSubmit.Attributes.Add("onclick","javascript:fnSomeFunctionInJavascript()");

Q31. How to register a client side script from code-behind?
Ans. Use the Page.RegisterClientScriptBlock method in the server side code to register the script that may be built using a StringBuilder.

Q32. Can a single .NET DLL contain multiple classes?
Ans. Yes, a single .NET DLL may contain any number of classes within it.

Q33. What is DLL Hell?
Ans. DLL Hell is the name given to the problem of old unmanaged DLL's due to which there was a possibility of version conflict among the DLLs.

Q34. can we put a break statement in a finally block?
Ans. The finally block cannot have the break, continue, return and goto statements.

Q35. What is a CompositeControl in .NET?
Ans. CompositeControl is an abstract class in .NET that is inherited by those web controls that contain child controls within them.

Q36. Which control in asp.net is used to display data from an xml file and then displayed using XSLT?
Ans. Use the asp:Xml control and set its DocumentSource property for associating an xml file, and set its TransformSource property to set the xml control's xsl file for the XSLT transformation.

Q37. Can we run ASP.NET 1.1 application and ASP.NET 2.0 application on the same computer?
Ans. Yes, though changes in the IIS in the properties for the site have to be made during deployment of each.

Q38. What are the new features in .NET 2.0?
Ans. Plenty of new controls, Generics, anonymous methods, partial classes, iterators, property visibility (separate visibility for get and set) and static classes.

Q39. Can we pop a MessageBox in a web application?
Ans. Yes, though this is done clientside using an alert, prompt or confirm or by opening a new web page that looks like a messagebox.

Q40. What is managed data?
Ans. The data for which the memory management is taken care by .Net runtimeâ€™s garbage collector, and this includes tasks for allocation de-allocation.

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Short Answer .NET Interview Questions (PAGE 3)

Q41. How to instruct the garbage collector to collect unreferenced data?
Ans. We may call the garbage collector to collect unreferenced data by executing the System.GC.Collect() method.

Q42. How can we set the Focus on a control in ASP.NET?
Ans. txtBox123.Focus(); OR Page.SetFocus(NameOfControl);

Q43. What are Partial Classes in Asp.Net 2.0?
Ans. In .NET 2.0, a class definition may be split into multiple physical files but partial classes do not make any difference to the compiler as during compile time, the compiler groups all the partial classes and treats them as a single class.

Q44. How to set the default button on a Web Form?
Ans. <asp:form id="form1" runat="server" defaultbutton="btnGo"/>

Q45.Can we force the garbage collector to run?
Ans. Yes, using the System.GC.Collect(), the garbage collector is forced to run in case required to do so.

Q46. What is Boxing and Unboxing?
Ans. Boxing is the process where any value type can be implicitly converted to a reference type object while Unboxing is the opposite of boxing process where the reference type is converted to a value type.

Q47. What is Code Access security? What is CAS in .NET?
Ans. CAS is the feature of the .NET security model that determines whether an application or a piece of code is permitted to run and decide the resources it can use while running.

Q48. What is Multi-tasking?
Ans. It is a feature of operating systems through which multiple programs may run on the operating system at the same time, just like a scenario where a Notepad, a Calculator and the Control Panel are open at the same time.

Q49. What is Multi-threading?
Ans. When an application performs different tasks at the same time, the application is said to exhibit multithreading as several threads of a process are running.2

Q50. What is a Thread?
Ans. A thread is an activity started by a process and its the basic unit to which an operating system allocates processor resources.

Q51. What does AddressOf in VB.NET operator do?
Ans. The AddressOf operator is used in VB.NET to create a delegate object to a method in order to point to it.

Q52. How to refer to the current thread of a method in .NET?
Ans. In order to refer to the current thread in .NET, the Thread.CurrentThread method can be used. It is a public static property.

Q53. How to pause the execution of a thread in .NET?
Ans. The thread execution can be paused by invoking the Thread.Sleep(IntegerValue) method where IntegerValue is an integer that determines the milliseconds time frame for which the thread in context has to sleep.

Q54. How can we force a thread to sleep for an infinite period?
Ans. Call the Thread.Interupt() method.

Q55. What is Suspend and Resume in .NET Threading?
Ans. Just like a song may be paused and played using a music player, a thread may be paused using Thread.Suspend method and may be started again using the Thread.Resume method. Note that sleep method immediately forces the thread to sleep whereas the suspend method waits for the thread to be in a persistable position before pausing its activity.

Q56. How can we prevent a deadlock in .Net threading?
Ans. Using methods like Monitoring, Interlocked classes, Wait handles, Event raising from between threads, using the ThreadState property.

Q57. What is Ajax?
Ans. Asyncronous Javascript and XML - Ajax is a combination of client side technologies that sets up asynchronous communication between the user interface and the web server so that partial page rendering occur instead of complete page postbacks.

Q58. What is XmlHttpRequest in Ajax?
Ans. It is an object in Javascript that allows the browser to communicate to a web server asynchronously without making a postback.

Q59. What are the different modes of storing an ASP.NET session?
Ans. InProc (the session state is stored in the memory space of the Aspnet_wp.exe process but the session information is lost when IIS reboots), StateServer (the Session state is serialized and stored in a separate process call Viewstate is an object in .NET that automatically persists control setting values across the multiple requests for the same page and it is internally maintained as a hidden field on the web page though its hashed for security reasons.

Q60. What is a delegate in .NET?
Ans. A delegate in .NET is a class that can have a reference to a method, and this class has a signature that can refer only those methods that have a signature which complies with the class.

Short Answer .NET Interview Questions (PAGE 4)

Q61. Is a delegate a type-safe functions pointer?
Ans. Yes

Q62. What is the return type of an event in .NET?
Ans. There is No return type of an event in .NET.

Q63. Is it possible to specify an access specifier to an event in .NET?
Ans. Yes, though they are public by default.

Q64. Is it possible to create a shared event in .NET?
Ans. Yes, but shared events may only be raised by shared methods.

Q65. How to prevent overriding of a class in .NET?
Ans. Use the keyword NotOverridable in VB.NET and sealed in C#.

Q66. How to prevent inheritance of a class in .NET?
Ans. Use the keyword NotInheritable in VB.NET and sealed in C#.

Q67. What is the purpose of the MustInherit keyword in VB.NET?
Ans. MustInherit keyword in VB.NET is used to create an abstract class.

Q68. What is the access modifier of a member function of in an Interface created in .NET?
Ans. It is always public, we cant use any other modifier other than the public modifier for the member functions of an Interface.

Q69. What does the virtual keyword in C# mean?
Ans. The virtual keyword signifies that the method and property may be overridden.

Q70. How to create a new unique ID for a control?
Ans. ControlName.ID = "ControlName" + Guid.NewGuid().ToString(); //Make use of the Guid class

Q71A. What is a HashTable in .NET?
Ans. A Hashtable is an object that implements the IDictionary interface, and can be used to store key value pairs. The key may be used as the index to access the values for that index.

Q71B. What is an ArrayList in .NET?
Ans. Arraylist object is used to store a list of values in the form of a list, such that the size of the arraylist can be increased and decreased dynamically, and moreover, it may hold items of different types. Items in an arraylist may be accessed using an index.

Q72. What is the value of the first item in an Enum? 0 or 1?
Ans. 0

Q73. Can we achieve operator overloading in VB.NET?
Ans. Yes, it is supported in the .NET 2.0 version, the "operator" keyword is used.

Q74. What is the use of Finalize method in .NET?
Ans. .NET Garbage collector performs all the clean up activity of the managed objects, and so the finalize method is usually used to free up the unmanaged objects like File objects, Windows API objects, Database connection objects, COM objects etc.

Q75. How do you save all the data in a dataset in .NET?
Ans. Use the AcceptChanges method which commits all the changes made to the dataset since last time Acceptchanges was performed.

Q76. Is there a way to suppress the finalize process inside the garbage collector forcibly in .NET?
Ans. Use the GC.SuppressFinalize() method.

Q77. What is the use of the dispose() method in .NET?
Ans. The Dispose method in .NET belongs to IDisposable interface and it is best used to release unmanaged objects like File objects, Windows API objects, Database connection objects, COM objects etc from the memory. Its performance is better than the finalize() method.

Q78. Is it possible to have have different access modifiers on the get and set methods of a property in .NET?
Ans. No we can not have different modifiers of a common property, which means that if the access modifier of a property's get method is protected, and it must be protected for the set method as well.

Q79. In .NET, is it possible for two catch blocks to be executed in one go?
Ans. This is NOT possible because once the correct catch block is executed then the code flow goes to the finally block.

Q80. Is there any difference between System.String and System.StringBuilder classes?
Ans. System.String is immutable by nature whereas System.StringBuilder can have a mutable string in which plenty of processes may be performed.

Short Answer .NET Interview Questions (PAGE 5)

Q81. What technique is used to figure out that the page request is a postback?
Ans. The IsPostBack property of the page object may be used to check whether the page request is a postback or not. IsPostBack property is of the type Boolean.

Q82. Which event of the ASP.NET page life cycle completely loads all the controls on the web page?
Ans. The Page_load event of the ASP.NET page life cycle assures that all controls are completely loaded. Even though the controls are also accessible in Page_Init event but here, the viewstate is incomplete.

Q83. How is ViewState information persisted across postbacks in an ASP.NET webpage?
Ans. Using HTML Hidden Fields, ASP.NET creates a hidden field with an ID="__VIEWSTATE" and the value of the page's viewstate is encoded (hashed) for security.

Q84. What is the ValidationSummary control in ASP.NET used for?
Ans. The ValidationSummary control in ASP.NET displays summary of all the current validation errors.

Q85. What is AutoPostBack feature in ASP.NET?
Ans. In case it is required for a server side control to postback when any of its event is triggered, then the AutoPostBack property of this control is set to true.

Q86. What is the difference between Web.config and Machine.Config in .NET?
Ans. Web.config file is used to make the settings to a web application, whereas Machine.config file is used to make settings to all ASP.NET applications on a server(the server machine).

Q87. What is the difference between a session object and an application object?
Ans. A session object can persist information between HTTP requests for a particular user, whereas an application object can be used globally for all the users.

Q88. Which control has a faster performance, Repeater or Datalist?
Ans. Repeater.

Q89. Which control has a faster performance, Datagrid or Datalist?
Ans. Datalist.

Q90. How to we add customized columns in a Gridview in ASP.NET?
Ans. Make use of the TemplateField column.

Q91. Is it possible to stop the clientside validation of an entire page?
Ans. Set Page.Validate = false;

Q92. Is it possible to disable client side script in validators?
Ans. Yes. simply EnableClientScript = false.

Q93. How do we enable tracing in .NET applications?
Ans. <%@ Page Trace="true" %>

Q94. How to kill a user session in ASP.NET?
Ans. Use the Session.abandon() method.

Q95. Is it possible to perform forms authentication with cookies disabled on a browser?
Ans. Yes, it is possible.

Q96. What are the steps to use a checkbox in a gridview?
Ans. <ItemTemplate>
<asp:CheckBox id="CheckBox1" runat="server" AutoPostBack="True"
OnCheckedChanged="Check_Clicked"></asp:CheckBox>
</ItemTemplate>

Q97. What are design patterns in .NET?
Ans. A Design pattern is a repeatitive solution to a repeatitive problem in the design of a software architecture.

Q98. What is difference between dataset and datareader in ADO.NET?
Ans. A DataReader provides a forward-only and read-only access to data, while the DataSet object can carry more than one table and at the same time hold the relationships between the tables. Also note that a DataReader is used in a connected architecture whereas a Dataset is used in a disconnected architecture.

Q99. Can connection strings be stored in web.config?
Ans. Yes, in fact this is the best place to store the connection string information.

Q100. Whats the difference between web.config and app.config?
Ans. Web.config is used for web based asp.net applications whereas app.config is used for windows based applications.

How many types of assemblies are there in the visual studio.net?	Six-Sigma	1
what to choose among testing, .net , and java for a B-Tech (ECE) fresher.		1
what is the difference between value types and reference types?	Six-Sigma	3
Navigation controls in ASP.net,explain each control in brief?	Six-Sigma	2
what is ado.net	HCL	8
Which Binding best suits where a WCF Service and the client application resides in the same machine?	Cap-Gemini	1
7. Oop-Diff B/w Interfacse and abstract class.	PCS	2
how do u achieve multilevel inheritance in .NET ?	Ness-Technologies	9
what is the difference between Exportdll and Importdll ?		1
what is stage management ? (ASP.NET)	Ness-Technologies	5
What is a sealed Class? What is the differnce between sealed class and private class?	iGate	2
how can u manage sessions ?	Ness-Technologies	3

ASP.Net and ASP.Net MVC Tutorial

Monday, August 19, 2013

.Net Interview Questions and Answers Volume-III

.Net Interview Questions and Answers Volume-III

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