Dot Net Interview Questions - Part 2 Interview question

1. What are Satellite Assemblies? How you will create this? How will you get the different language strings?
   Satellite assemblies are often used to deploy language-specific resources for an application. These language-specific assemblies work in side-by-side execution because the application has a separate product ID for each language and installs satellite assemblies in a language-specific subdirectory for each language. When uninstalling, the application removes only the satellite assemblies associated with a given language and .NET Framework version. No core .NET Framework files are removed unless the last language for that .NET Framework version is being removed.
   (For example, English and Japanese editions of the .NET Framework version 1.1 share the same core files. The Japanese .NET Framework version 1.1 adds satellite assemblies with localized resources in a \ja subdirectory. An application that supports the .NET Framework version 1.1, regardless of its language, always uses the same core runtime files.)
2. How will u load dynamic assembly? How will create assemblies at run time?
3. What is Assembly manifest? what all details the assembly manifest will contain?
   Every assembly, whether static or dynamic, contains a collection of data that describes how the elements in the assembly relate to each other. The assembly manifest contains this assembly metadata. An assembly manifest contains all the metadata needed to specify the assembly's version requirements and security identity, and all metadata needed to define the scope of the assembly and resolve references to resources and classes. The assembly manifest can be stored in either a PE file (an .exe or .dll) with Microsoft intermediate language (MSIL) code or in a standalone PE file that contains only assembly manifest information.
   It contains Assembly name, Version number, Culture, Strong name information, List of all files in the assembly, Type reference information, Information on referenced assemblies.
4. 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.
5. What is Global Assembly Cache (GAC) and what is the purpose of it? (How to make an assembly to public? Steps) How more than one version of an assembly can keep in same place?
   Each computer where the common language runtime is installed has a machine-wide code cache called the global assembly cache. The global assembly cache stores assemblies specifically designated to be shared by several applications on the computer. You should share assemblies by installing them into the global assembly cache only when you need to.
   Steps
   - Create a strong name using sn.exe tool
   eg: sn -k keyPair.snk
   - with in AssemblyInfo.cs add the generated file name
   eg: [assembly: AssemblyKeyFile("abc.snk")]
   - recompile project, then install it to GAC by either
   drag & drop it to assembly folder (C:\WINDOWS\assembly OR C:\WINNT\assembly) (shfusion.dll tool)
   or
   gacutil -i abc.dll
6. If I have more than one version of one assemblies, then how'll I use old version (how/where to specify version number?)in my application?
7. How to find methods of a assembly file (not using ILDASM)
   Reflection
8. What is Garbage Collection in .Net? Garbage collection process?
   The process of transitively tracing through all pointers to actively used objects in order to locate all objects that can be referenced, and then arranging to reuse any heap memory that was not found during this trace. The common language runtime garbage collector also compacts the memory that is in use to reduce the working space needed for the heap.
9. What is Reflection in .NET? Namespace? How will you load an assembly which is not referenced by current assembly?
   All .NET compilers produce metadata about the types defined in the modules they produce. This metadata is packaged along with the module (modules in turn are packaged together in assemblies), and can be accessed by a mechanism called reflection. The System.Reflection namespace contains classes that can be used to interrogate the types for a module/assembly.
   Using reflection to access .NET metadata is very similar to using ITypeLib/ITypeInfo to access type library data in COM, and it is used for similar purposes - e.g. determining data type sizes for marshaling data across context/process/machine boundaries.
   Reflection can also be used to dynamically invoke methods (see System.Type.InvokeMember), or even create types dynamically at run-time (see System.Reflection.Emit.TypeBuilder).
10. What is Custom attribute? How to create? If I'm having custom attribute in an assembly, how to say that name in the code?
    A: The primary steps to properly design custom attribute classes are as follows:

0. Applying the AttributeUsageAttribute ([AttributeUsage(AttributeTargets.All, Inherited = false, AllowMultiple = true)])
1. Declaring the attribute. (class public class MyAttribute : System.Attribute { // . . . })
2. Declaring constructors (public MyAttribute(bool myvalue) { this.myvalue = myvalue; })
3. Declaring properties
   public bool MyProperty
   {
   get {return this.myvalue;}
   set {this.myvalue = value;}
   }

The following example demonstrates the basic way of using reflection to get access to custom attributes.
class MainClass
{
public static void Main()
{
System.Reflection.MemberInfo info = typeof(MyClass);
object[] attributes = info.GetCustomAttributes();
for (int i = 0; i <>
{
System.Console.WriteLine(attributes[i]);
}
}
}

11. What is the managed and unmanaged code in .net?
    The .NET Framework provides a run-time environment called the Common Language Runtime, which manages the execution of code and provides services that make the development process easier. Compilers and tools expose the runtime's functionality and enable you to write code that benefits from this managed execution environment. Code that you develop with a language compiler that targets the runtime is called managed code; it benefits from features such as cross-language integration, cross-language exception handling, enhanced security, versioning and deployment support, a simplified model for component interaction, and debugging and profiling services.
12. How do you create threading in .NET? What is the namespace for that?
    System.Threading.Thread
13. Serialize and MarshalByRef?
14. using directive vs using statement :
    You create an instance in a using statement to ensure that Dispose is called on the object when the using statement is exited. A using statement can be exited either when the end of the using statement is reached or if, for example, an exception is thrown and control leaves the statement block before the end of the statement.
    The using directive has two uses:

• Create an alias for a namespace (a using alias).
• Permit the use of types in a namespace, such that, you do not have to qualify the use of a type in that namespace (a using directive).
14. Describe the Managed Execution Process?
    The managed execution process includes the following steps:

0. Choosing a compiler.
   To obtain the benefits provided by the common language runtime, you must use one or more language compilers that target the runtime.
1. Compiling your code to Microsoft intermediate language (MSIL).
   Compiling translates your source code into MSIL and generates the required metadata.
2. Compiling MSIL to native code.
   At execution time, a just-in-time (JIT) compiler translates the MSIL into native code. During this compilation, code must pass a verification process that examines the MSIL and metadata to find out whether the code can be determined to be type safe.
3. Executing your code.
   The common language runtime provides the infrastructure that enables execution to take place as well as a variety of services that can be used during execution.
15. What is Active Directory? What is the namespace used to access the Microsoft Active Directories? What are ADSI Directories?
    Active Directory Service Interfaces (ADSI) is a programmatic interface for Microsoft Windows Active Directory. It enables your applications to interact with diverse directories on a network, using a single interface. Visual Studio .NET and the .NET Framework make it easy to add ADSI functionality with the DirectoryEntry and DirectorySearcher components.
    Using ADSI, you can create applications that perform common administrative tasks, such as backing up databases, accessing printers, and administering user accounts. ADSI makes it possible for you to:

• Log on once to work with diverse directories. The DirectoryEntry component class provides username and password properties that can be entered at runtime and communicated to the Active Directory object you are binding to.
• Use a single application programming interface (API) to perform tasks on multiple directory systems by offering the user a variety of protocols to use. The DirectoryServices namespace provides the classes to perform most administrative functions.
• Perform "rich querying" on directory systems. ADSI technology allows for searching for an object by specifying two query dialects: SQL and LDAP.
• Access and use a single, hierarchical structure for administering and maintaining diverse and complicated network configurations by accessing an Active Directory tree.
• Integrate directory information with databases such as SQL Server. The DirectoryEntry path may be used as an ADO.NET connection string provided that it is using the LDAP provider.

using System.DirectoryServices;

17. How Garbage Collector (GC) Works?
    The methods in this class influence when an object is garbage collected and when resources allocated by an object are released. Properties in this class provide information about the total amount of memory available in the system and the age category, or generation, of memory allocated to an object. Periodically, the garbage collector performs garbage collection to reclaim memory allocated to objects for which there are no valid references. Garbage collection happens automatically when a request for memory cannot be satisfied using available free memory. Alternatively, an application can force garbage collection using the Collect method.
    Garbage collection consists of the following steps:

0. The garbage collector searches for managed objects that are referenced in managed code.
1. The garbage collector attempts to finalize objects that are not referenced.
2. The garbage collector frees objects that are not referenced and reclaims their memory.
17. Why do we need to call CG.SupressFinalize?
    Requests that the system not call the finalizer method for the specified object.
    [C#]
    public static void SuppressFinalize(object obj);

The method removes obj from the set of objects that require finalization. The obj parameter is required to be the caller of this method.
Objects that implement the IDisposable interface can call this method from the IDisposable.Dispose method to prevent the garbage collector from calling Object.Finalize on an object that does not require it.

19. What is nmake tool?
    The Nmake tool (Nmake.exe) is a 32-bit tool that you use to build projects based on commands contained in a .mak file.
    usage : nmake -a all

20 . What are Namespaces?
The namespace keyword is used to declare a scope. This namespace scope lets you organize code and gives you a way to create globally-unique types. Even if you do not explicitly declare one, a default namespace is created. This unnamed namespace, sometimes called the global namespace, is present in every file. Any identifier in the global namespace is available for use in a named namespace. Namespaces implicitly have public access and this is not modifiable.

Dot Net Interview Questions - Part 4 Interview question

1. What is the new three features of COM+ services, which are not there in COM (MTS)?
2. Is the COM architecture same as .Net architecture? What is the difference between them?
3. Can we copy a COM dll to GAC folder?
4. What is Pinvoke?
   Platform invoke is a service that enables managed code to call unmanaged functions implemented in dynamic-link libraries (DLLs), such as those in the Win32 API. It locates and invokes an exported function and marshals its arguments (integers, strings, arrays, structures, and so on) across the interoperation boundary as needed.
5. Is it true that COM objects no longer need to be registered on the server?
   Answer: Yes and No. Legacy COM objects still need to be registered on the server before they can be used. COM developed using the new .NET Framework will not need to be registered. Developers will be able to auto-register these objects just by placing them in the 'bin' folder of the application.
6. Can .NET Framework components use the features of Component Services?
   Answer: Yes, you can use the features and functions of Component Services from a .NET Framework component.
7. What are the OOPS concepts?
   1) Encapsulation: It is the mechanism that binds together code and data in manipulates, and keeps both safe from outside interference and misuse. In short it isolates a particular code and data from all other codes and data. A well-defined interface controls the access to that particular code and data.
   2) Inheritance: It is the process by which one object acquires the properties of another object. This supports the hierarchical classification. Without the use of hierarchies, each object would need to define all its characteristics explicitly. However, by use of inheritance, an object need only define those qualities that make it unique within its class. It can inherit its general attributes from its parent. A new sub-class inherits all of the attributes of all of its ancestors.
   3) Polymorphism: It is a feature that allows one interface to be used for general class of actions. The specific action is determined by the exact nature of the situation. In general polymorphism means "one interface, multiple methods", This means that it is possible to design a generic interface to a group of related activities. This helps reduce complexity by allowing the same interface to be used to specify a general class of action. It is the compiler's job to select the specific action (that is, method) as it applies to each situation.
8. 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.
9. Value type & reference types difference? Example from .NET. Integer & struct are value types or reference types in .NET?
   Most programming languages provide built-in data types, such as integers and floating-point numbers, that are copied when they are passed as arguments (that is, they are passed by value). In the .NET Framework, these are called value types. The runtime supports two kinds of value types:
• Built-in value types
  The .NET Framework defines built-in value types, such as System.Int32 and System.Boolean, which correspond and are identical to primitive data types used by programming languages.
• User-defined value types
  Your language will provide ways to define your own value types, which derive from System.ValueType. If you want to define a type representing a value that is small, such as a complex number (using two floating-point numbers), you might choose to define it as a value type because you can pass the value type efficiently by value. If the type you are defining would be more efficiently passed by reference, you should define it as a class instead.

Variables of reference types, referred to as objects, store references to the actual data. This following are the reference types:

• class
• interface
• delegate

This following are the built-in reference types:

• object
• string
9. What is Inheritance, Multiple Inheritance, Shared and Repeatable Inheritance?
10. What is Method overloading?
    Method overloading occurs when a class contains two methods with the same name, but different signatures.
11. What is Method Overriding? How to override a function in C#?
    Use the override modifier to modify a method, a property, an indexer, or an event. An override method provides a new implementation of a member inherited from a base class. The method overridden by an override declaration is known as the overridden base method. The overridden base method must have the same signature as the override method.
    You cannot override a non-virtual or static method. The overridden base method must be virtual, abstract, or override.
12. Can we call a base class method without creating instance?
    Its possible If its a static method.
    Its possible by inheriting from that class also.
    Its possible from derived classes using base keyword.
13. You have one base class virtual function how will call that function from derived class?
    class a

   {

      public virtual int m()

      {

         return 1;

      }

   }

   class b:a

   {

      public int j()

      {

         return m();

      }

}

15. In which cases you use override and new base?
    Use the new modifier to explicitly hide a member inherited from a base class. To hide an inherited member, declare it in the derived class using the same name, and modify it with the new modifier.

---C# Language features---

16. What are Sealed Classes in C#?
    The sealed modifier is used to prevent derivation from a class. A compile-time error occurs if a sealed class is specified as the base class of another class. (A sealed class cannot also be an abstract class)
17. What is Polymorphism? How does VB.NET/C# achieve polymorphism?
18. class Token

   {

      public string Display()

      {

       //Implementation goes here

       return "base";

      }

   }

   class IdentifierToken:Token

   {

      public new string Display() //What is the use of new keyword

      {

       //Implementation goes here

       return "derive";

      }

   }

      static void Method(Token t)

      {

        Console.Write(t.Display());

      }

      public static void Main()

      {

        IdentifierToken Variable=new IdentifierToken();

        Method(Variable); //Which Class Method is called here

        Console.ReadLine();

      }

For the above code What is the "new" keyword and Which Class Method is called here

Ans: it will call base class Display method

       class Token

       {

         public virtual string Display()

         {

          //Implementation goes here

          return "base";

         }

       }

       class IdentifierToken:Token

       {

         public override string Display() //What is the use of new keyword

         {

          //Implementation goes here

          return "derive";

         }

       }

       static void Method(Token t)

       {

         Console.Write(t.Display());

       }

       public static void Main()

       {

         IdentifierToken Variable=new IdentifierToken();

         Method(Variable); //Which Class Method is called here

         Console.ReadLine();

       }

A: Derive

19. In which Scenario you will go for Interface or Abstract Class?
    Interfaces, like classes, define a set of properties, methods, and events. But unlike classes, interfaces do not provide implementation. They are implemented by classes, and defined as separate entities from classes. Even though class inheritance allows your classes to inherit implementation from a base class, it also forces you to make most of your design decisions when the class is first published.
    Abstract classes are useful when creating components because they allow you specify an invariant level of functionality in some methods, but leave the implementation of other methods until a specific implementation of that class is needed. They also version well, because if additional functionality is needed in derived classes, it can be added to the base class without breaking code.

Feature	Interface	Abstract class
Multiple inheritance	A class may implement several interfaces.	A class may extend only one abstract class.
Default implementation	An interface cannot provide any code at all, much less default code.	An abstract class can provide complete code, default code, and/or just stubs that have to be overridden.
Constants	Static final constants only, can use them without qualification in classes that implement the interface. On the other paw, these unqualified names pollute the namespace. You can use them and it is not obvious where they are coming from since the qualification is optional.	Both instance and static constants are possible. Both static and instance intialiser code are also possible to compute the constants.
Third party convenience	An interface implementation may be added to any existing third party class.	A third party class must be rewritten to extend only from the abstract class.
is-a vs -able or can-do	Interfaces are often used to describe the peripheral abilities of a class, not its central identity, e.g. an Automobile class might implement the Recyclable interface, which could apply to many otherwise totally unrelated objects.	An abstract class defines the core identity of its descendants. If you defined a Dog abstract class then Damamation descendants are Dogs, they are not merely dogable. Implemented interfaces enumerate the general things a class can do, not the things a class is.
Plug-in	You can write a new replacement module for an interface that contains not one stick of code in common with the existing implementations. When you implement the interface, you start from scratch without any default implementation. You have to obtain your tools from other classes; nothing comes with the interface other than a few constants. This gives you freedom to implement a radically different internal design.	You must use the abstract class as-is for the code base, with all its attendant baggage, good or bad. The abstract class author has imposed structure on you. Depending on the cleverness of the author of the abstract class, this may be good or bad. Another issue that's important is what I call "heterogeneous vs. homogeneous." If implementors/subclasses are homogeneous, tend towards an abstract base class. If they are heterogeneous, use an interface. (Now all I have to do is come up with a good definition of hetero/homogeneous in this context.) If the various objects are all of-a-kind, and share a common state and behavior, then tend towards a common base class. If all they share is a set of method signatures, then tend towards an interface.
Homogeneity	If all the various implementations share is the method signatures, then an interface works best.	If the various implementations are all of a kind and share a common status and behavior, usually an abstract class works best.
Maintenance	If your client code talks only in terms of an interface, you can easily change the concrete implementation behind it, using a factory method.	Just like an interface, if your client code talks only in terms of an abstract class, you can easily change the concrete implementation behind it, using a factory method.
Speed	Slow, requires extra indirection to find the corresponding method in the actual class. Modern JVMs are discovering ways to reduce this speed penalty.	Fast
Terseness	The constant declarations in an interface are all presumed public static final, so you may leave that part out. You can't call any methods to compute the initial values of your constants. You need not declare individual methods of an interface abstract. They are all presumed so.	You can put shared code into an abstract class, where you cannot into an interface. If interfaces want to share code, you will have to write other bubblegum to arrange that. You may use methods to compute the initial values of your constants and variables, both instance and static. You must declare all the individual methods of an abstract class abstract.
Adding functionality	If you add a new method to an interface, you must track down all implementations of that interface in the universe and provide them with a concrete implementation of that method.	If you add a new method to an abstract class, you have the option of providing a default implementation of it. Then all existing code will continue to work without change.

Q:1     interface ICommon

     {

      int getCommon();

     }

     interface ICommonImplements1:ICommon

     {

     }

     interface ICommonImplements2:ICommon

     {

     }

     public class a:ICommonImplements1,ICommonImplements2

     {

        }

How to implement getCommon method in class a? Are you seeing any problem in the implementation?

        public class a:ICommonImplements1,ICommonImplements2

  {

   public int getCommon()

   {

    return 1;

   }

  }

Q:2     interface IWeather

     {

       void display();

     }

     public class A:IWeather

     {

       public void display()

       {

         MessageBox.Show("A");

       }

     }

     public class B:A

     {

     }

     public class C:B,IWeather

     {

       public void display()

       {

         MessageBox.Show("C");

       }

     }

When I instantiate C.display(), will it work?

Q:3     interface IPrint

     {

       string Display();

     }

     interface IWrite

     {

       string Display();

      }

      class PrintDoc:IPrint,IWrite

      {

       //Here is implementation

      }

how to implement the Display in the class printDoc (How to resolve the naming Conflict)

Ans: no naming conflicts

   class PrintDoc:IPrint,IWrite

   {

     public string Display()

     {

      return "s";

     }

    }

Q:4     interface IList

      {

        int Count { get; set; }

      }

      interface ICounter

      {

        void Count(int i);

      }

      interface IListCounter: IList, ICounter {}

      class C

      {

        void Test(IListCounter x)

        {

          x.Count(1);                // Error

          x.Count = 1;               // Error

          ((IList)x).Count = 1;      // Ok, invokes IList.Count.set

          ((ICounter)x).Count(1);    // Ok, invokes ICounter.Count

        }

      }

Write one code example for compile time binding and one for run time binding? What is early/late binding?
An object is early bound when it is assigned to a variable declared to be of a specific object type. Early bound objects allow the compiler to allocate memory and perform other optimizations before an application executes.
' Create a variable to hold a new object.
Dim FS As FileStream
' Assign a new object to the variable.
FS = New FileStream("C:\tmp.txt", FileMode.Open)
By contrast, an object is late bound when it is assigned to a variable declared to be of type Object. Objects of this type can hold references to any object, but lack many of the advantages of early-bound objects.
Dim xlApp As Object
xlApp = CreateObject("Excel.Application")

Dot Net Interview Questions - Part 3

1. What is the difference between CONST and READONLY?
   Both are meant for constant values. A const field can only be initialized at the declaration of the field. A readonly field can be initialized either at the declaration or in a constructor. Therefore, readonly fields can have different values depending on the constructor used.
   readonly int b;
   public X()
   {
   b=1;
   }
   public X(string s)
   {
   b=5;
   }
   public X(string s, int i)
   {
   b=i;
   }
   Also, while a const field is a compile-time constant, the readonly field can be used for runtime constants, as in the following example:
   public static readonly uint l1 = (uint) DateTime.Now.Ticks; (this can't be possible with const)
2. 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.
3. What is the difference between Array and LinkedList?
4. What is the difference between Array and Arraylist?
   As elements are added to an ArrayList, the capacity is automatically increased as required through reallocation. The capacity can be decreased by calling TrimToSize or by setting the Capacity property explicitly.
5. What is Jagged Arrays?
   A jagged array is an array whose elements are arrays. The elements of a jagged array can be of different dimensions and sizes. A jagged array is sometimes called an "array-of-arrays."
6. What are indexers?
   Indexers are similar to properties, except that the get and set accessors of indexers take parameters, while property accessors do not.
7. What is Asynchronous call and how it can be implemented using delegates?
8. How to create events for a control? What is custom events? How to create it?
9. If you want to write your own dot net language, what steps you will u take care?
10. Describe the difference between inline and code behind - which is best in a loosely coupled solution?
11. how dot net compiled code will become platform independent?
12. without modifying source code if we compile again, will it be generated MSIL again?
13. C++ & C# differences

14. Interop Services?
    The common language runtime provides two mechanisms for interoperating with unmanaged code:

• Platform invoke, which enables managed code to call functions exported from an unmanaged library.
• COM interop, which enables managed code to interact with COM objects through interfaces.

Both platform invoke and COM interop use interop marshaling to accurately move method arguments between caller and callee and back, if required.

15. How does u handle this COM components developed in other programming languages in .NET?
16. What is RCW (Runtime Callable Wrappers)?
    The common language runtime exposes COM objects through a proxy called the runtime callable wrapper (RCW). Although the RCW appears to be an ordinary object to .NET clients, its primary function is to marshal calls between a .NET client and a COM object.
17. What is CCW (COM Callable Wrapper)

A proxy object generated by the common language runtime so that existing COM applications can use managed classes, including .NET Framework classes, transparently.

18. How CCW and RCW is working?
19. How will you register com+ services?
    The .NET Framework SDK provides the .NET Framework Services Installation Tool (Regsvcs.exe - a command-line tool) to manually register an assembly containing serviced components. You can also access these registration features programmatically with the System.EnterpriseServicesRegistrationHelper class by creating an instance of class RegistrationHelper and using the method InstallAssembly

What is use of ContextUtil class?
ContextUtil is the preferred class to use for obtaining COM+ context information.

Dot Net Interview Questions - Part 5 Interview question

1. Can you explain what inheritance is and an example of when you might use it?
2. How can you write a class to restrict that only one object of this class can be created (Singleton class)?
3. What are the access-specifiers available in c#?
   Private, Protected, Public, Internal, Protected Internal.
4. Explain about Protected and protected internal, “internal” access-specifier?
   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.
5. 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.
   A static constructor is used to initialize a class. It is called automatically to initialize the class before the first instance is created or any static members are referenced.
6. What is Private Constructor? and it’s use? Can you create instance of a class which has Private Constructor?
   A: When a class declares only private instance constructors, it is not possible for classes outside the program to derive from the class or to directly create instances of it. (Except Nested classes)
   Make a constructor private if:
   - You want it to be available only to the class itself. For example, you might have a special constructor used only in the implementation of your class' Clone method.
   - You do not want instances of your component to be created. For example, you may have a class containing nothing but Shared utility functions, and no instance data. Creating instances of the class would waste memory.
7. I have 3 overloaded constructors in my class. In order to avoid making instance of the class do I need to make all constructors to private?(yes)
8. Overloaded constructor will call default constructor internally?(no)
9. What are virtual destructors?
10. Destructor and finalize
    Generally in C++ the destructor is called when objects gets destroyed. And one can explicitly call the destructors in C++. And also the objects are destroyed in reverse order that they are created in. So in C++ you have control over the destructors.
    In C# you can never call them, the reason is one cannot destroy an object. So who has the control over the destructor (in C#)? it's the .Net frameworks Garbage Collector (GC). GC destroys the objects only when necessary. Some situations of necessity are memory is exhausted or user explicitly calls System.GC.Collect() method.
    Points to remember:
    1. Destructors are invoked automatically, and cannot be invoked explicitly.
    2. Destructors cannot be overloaded. Thus, a class can have, at most, one destructor.
    3. Destructors are not inherited. Thus, a class has no destructors other than the one, which may be declared in it.
    4. Destructors cannot be used with structs. They are only used with classes.
    5. An instance becomes eligible for destruction when it is no longer possible for any code to use the instance.
    6. Execution of the destructor for the instance may occur at any time after the instance becomes eligible for destruction.
    7. When an instance is destructed, the destructors in its inheritance chain are called, in order, from most derived to least derived.
    
11. What is the difference between Finalize and Dispose (Garbage collection)
    Class instances often encapsulate control over resources that are not managed by the runtime, such as window handles (HWND), database connections, and so on. Therefore, you should provide both an explicit and an implicit way to free those resources. Provide implicit control by implementing the protected Finalize Method on an object (destructor syntax in C# and the Managed Extensions for C++). The garbage collector calls this method at some point after there are no longer any valid references to the object.
    In some cases, you might want to provide programmers using an object with the ability to explicitly release these external resources before the garbage collector frees the object. If an external resource is scarce or expensive, better performance can be achieved if the programmer explicitly releases resources when they are no longer being used. To provide explicit control, implement the Dispose method provided by the IDisposable Interface. The consumer of the object should call this method when it is done using the object. Dispose can be called even if other references to the object are alive.
    Note that even when you provide explicit control by way of Dispose, you should provide implicit cleanup using the Finalize method. Finalize provides a backup to prevent resources from permanently leaking if the programmer fails to call Dispose.
12. What is close method? How its different from Finalize & Dispose?
13. What is boxing & unboxing?
14. What is check/uncheck?
15. What is the use of base keyword? Tell me a practical example for base keyword’s usage?
16. What are the different .net tools which u used in projects?
17. try
    {
    ...
    }
    catch
    {
    ...//exception occurred here. What'll happen?
    }
    finally
    {
    ..
    }
    Ans : It will throw exception.
18. What will do to avoid prior case?
    try

   {

    try

    {

      ...

    }

    catch

    {

     ...

     //exception occurred here.

    }

    finally

    {

     ...

    }

   }

   catch

   {

     ...

   }

   finally{...}

19.       try

     {

       ...

     }

     catch

     {

       ...

     }

     finally

     {

       ...

     } 

Will it go to finally block if there is no exception happened?
Ans: Yes. The finally block is useful for cleaning up any resources allocated in the try block. Control is always passed to the finally block regardless of how the try block exits.

Is goto statement supported in C#? How about Java?
Gotos are supported in C#to the fullest. In Java goto is a reserved keyword that provides absolutely no functionality

Dot Net Interview Questions - Part 6 Interview question

1. What’s different about switch statements in C#?
   No fall-throughs allowed. Unlike the C++ switch statement, C# does not support an explicit fall through from one case label to another. If you want, you can use goto a switch-case, or goto default.
   case 1:
   cost += 25;
   break;
   case 2:
   cost += 25;
   goto case 1;
   
   
   
2. Advantage of ADO.Net?
• ADO.NET Does Not Depend On Continuously Live Connections
• Database Interactions Are Performed Using Data Commands
• Data Can Be Cached in Datasets
• Datasets Are Independent of Data Sources
• Data Is Persisted as XML
• Schemas Define Data Structures
3. How would u connect to database using .NET?
   SqlConnection nwindConn = new SqlConnection("Data Source=localhost; Integrated Security=SSPI;" + "Initial Catalog=northwind");
   nwindConn.Open();
4. What are relation objects in dataset and how & where to use them?
   In a DataSet that contains multiple DataTable objects, you can use DataRelation objects to relate one table to another, to navigate through the tables, and to return child or parent rows from a related table. Adding a DataRelation to a DataSet adds, by default, a UniqueConstraint to the parent table and a ForeignKeyConstraint to the child table.
   The following code example creates a DataRelation using two DataTable objects in a DataSet. Each DataTable contains a column named CustID, which serves as a link between the two DataTable objects. The example adds a single DataRelation to the Relations collection of the DataSet. The first argument in the example specifies the name of the DataRelation being created. The second argument sets the parent DataColumn and the third argument sets the child DataColumn.
   custDS.Relations.Add("CustOrders",
   custDS.Tables["Customers"].Columns["CustID"],
   custDS.Tables["Orders"].Columns["CustID"]);
   
   OR
   private void CreateRelation()
   {
   // Get the DataColumn objects from two DataTable objects in a DataSet.
   DataColumn parentCol;
   DataColumn childCol;
   // Code to get the DataSet not shown here.
   parentCol = DataSet1.Tables["Customers"].Columns["CustID"];
   childCol = DataSet1.Tables["Orders"].Columns["CustID"];
   // Create DataRelation.
   DataRelation relCustOrder;
   relCustOrder = new DataRelation("CustomersOrders", parentCol, childCol);
   // Add the relation to the DataSet.
   DataSet1.Relations.Add(relCustOrder);
   }

5. Difference between OLEDB Provider and SqlClient ?
Ans: SQLClient .NET classes are highly optimized for the .net / sqlserver combination and achieve optimal results. The SqlClient data provider is fast. It's faster than the Oracle provider, and faster than accessing database via the OleDb layer. It's faster because it accesses the native library (which automatically gives you better performance), and it was written with lots of help from the SQL Server team.

6. What are the different namespaces used in the project to connect the database? What data providers available in .net to connect to database?
• System.Data.OleDb – classes that make up the .NET Framework Data Provider for OLE DB-compatible data sources. These classes allow you to connect to an OLE DB data source, execute commands against the source, and read the results.
• System.Data.SqlClient – classes that make up the .NET Framework Data Provider for SQL Server, which allows you to connect to SQL Server 7.0, execute commands, and read results. The System.Data.SqlClient namespace is similar to the System.Data.OleDb namespace, but is optimized for access to SQL Server 7.0 and later.
• System.Data.Odbc - classes that make up the .NET Framework Data Provider for ODBC. These classes allow you to access ODBC data source in the managed space.
• System.Data.OracleClient - classes that make up the .NET Framework Data Provider for Oracle. These classes allow you to access an Oracle data source in the managed space.
7. Difference between DataReader and DataAdapter / DataSet and DataAdapter?
   You can use the ADO.NET DataReader to retrieve a read-only, forward-only stream of data from a database. Using the DataReader can increase application performance and reduce system overhead because only one row at a time is ever in memory.
   After creating an instance of the Command object, you create a DataReader by calling Command.ExecuteReader to retrieve rows from a data source, as shown in the following example.
   SqlDataReader myReader = myCommand.ExecuteReader();
   You use the Read method of the DataReader object to obtain a row from the results of the query.
   while (myReader.Read())
   Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));
   myReader.Close();
   The DataSet is a memory-resident representation of data that provides a consistent relational programming model regardless of the data source. It can be used with multiple and differing data sources, used with XML data, or used to manage data local to the application. The DataSet represents a complete set of data including related tables, constraints, and relationships among the tables. The methods and objects in a DataSet are consistent with those in the relational database model. The DataSet can also persist and reload its contents as XML and its schema as XML Schema definition language (XSD) schema.
   The DataAdapter serves as a bridge between a DataSet and a data source for retrieving and saving data. The DataAdapter provides this bridge by mapping Fill, which changes the data in the DataSet to match the data in the data source, and Update, which changes the data in the data source to match the data in the DataSet. If you are connecting to a Microsoft SQL Server database, you can increase overall performance by using the SqlDataAdapter along with its associated SqlCommand and SqlConnection. For other OLE DB-supported databases, use the DataAdapter with its associated OleDbCommand and OleDbConnection objects.
8. Which method do you invoke on the DataAdapter control to load your generated dataset with data? Fill()
9. Explain different methods and Properties of DataReader which you have used in your project?
   1. Read
   2. GetString
   3. GetInt32
   while (myReader.Read())
   Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));
   myReader.Close();
10. What happens when we issue Dataset.ReadXml command?
    Reads XML schema and data into the DataSet.
11. In how many ways we can retrieve table records count? How to find the count of records in a dataset?
    foreach(DataTable thisTable in myDataSet.Tables){
    // For each row, print the values of each column.
    foreach(DataRow myRow in thisTable.Rows){
12. How to check if a datareader is closed or opened? IsClosed()
13. What happens when u try to update data in a dataset in .NET while the record is already deleted in SQL SERVER as backend?
    OR What is concurrency? How will you avoid concurrency when dealing with dataset? (One user deleted one row after that another user through his dataset was trying to update same row. What will happen? How will you avoid the problem?)
14. How do you merge 2 datasets into the third dataset in a simple manner? OR If you are executing these statements in commandObject. "Select * from Table1;Select * from Table2” how you will deal result set?
15. How do you sort a dataset?
16. If a dataset contains 100 rows, how to fetch rows between 5 and 15 only?
17. Differences between dataset.clone and dataset.copy?
    Clone - Copies the structure of the DataSet, including all DataTable schemas, relations, and constraints. Does not copy any data.
    Copy - Copies both the structure and data for this DataSet.
18. What is the use of parameter object?
19. How to generate XML from a dataset and vice versa?
20. What is method to get XML and schema from Dataset?
    ans: getXML () and get Schema ()

Dot Net Interview Questions - Part 7 Interview question

1. How do u implement locking concept for dataset?
   
   
2. Asp.net and asp – differences?

Code Render Block	Code Declaration Block
	Compiled
Request/Response	Event Driven
	Object Oriented - Constructors/Destructors, Inheritance, overloading..
	Exception Handling - Try, Catch, Finally
	Down-level Support
	Cultures
	User Controls
	In-built client side validation
Session - weren't transferable across servers	It can span across servers, It can survive server crashes, can work with browsers that don't support cookies
built on top of the window & IIS, it was always a separate entity & its functionality was limited.	its an integral part of OS under the .net framework. It shares many of the same objects that traditional applications would use, and all .net objects are available for asp.net's consumption.
	Garbage Collection
	Declare variable with datatype
	In built graphics support
	Cultures

3. How ASP and ASP.NET page works? Explain about asp.net page life cycle?
4. Order of events in an asp.net page? Control Execution Lifecycle?

Phase	What a control needs to do	Method or event to override
Initialize	Initialize settings needed during the lifetime of the incoming Web request.	Init event (OnInit method)
Load view state	At the end of this phase, the ViewState property of a control is automatically populated as described in Maintaining State in a Control. A control can override the default implementation of the LoadViewState method to customize state restoration.	LoadViewState method
Process postback data	Process incoming form data and update properties accordingly.	LoadPostData method (if IPostBackDataHandler is implemented)
Load	Perform actions common to all requests, such as setting up a database query. At this point, server controls in the tree are created and initialized, the state is restored, and form controls reflect client-side data.	Load event (OnLoad method)
Send postback change notifications	Raise change events in response to state changes between the current and previous postbacks.	RaisePostDataChangedEvent method (if IPostBackDataHandler is implemented)
Handle postback events	Handle the client-side event that caused the postback and raise appropriate events on the server.	RaisePostBackEvent method(if IPostBackEventHandler is implemented)
Prerender	Perform any updates before the output is rendered. Any changes made to the state of the control in the prerender phase can be saved, while changes made in the rendering phase are lost.	PreRender event (OnPreRender method)
Save state	The ViewState property of a control is automatically persisted to a string object after this stage. This string object is sent to the client and back as a hidden variable. For improving efficiency, a control can override the SaveViewState method to modify the ViewState property.	SaveViewState method
Render	Generate output to be rendered to the client.	Render method
Dispose	Perform any final cleanup before the control is torn down. References to expensive resources such as database connections must be released in this phase.	Dispose method
Unload	Perform any final cleanup before the control is torn down. Control authors generally perform cleanup in Dispose and do not handle this event.	UnLoad event (On UnLoad method)

Note To override an EventName event, override the OnEventName method (and call base.OnEventName)

5. What are server controls?
   ASP.NET server controls are components that run on the server and encapsulate user-interface and other related functionality. They are used in ASP.NET pages and in ASP.NET code-behind classes.
6. What is the difference between Web User Control and Web Custom Control?
   Custom Controls
   Web custom controls are compiled components that run on the server and that encapsulate user-interface and other related functionality into reusable packages. They can include all the design-time features of standard ASP.NET server controls, including full support for Visual Studio design features such as the Properties window, the visual designer, and the Toolbox.
   There are several ways that you can create Web custom controls:
• You can compile a control that combines the functionality of two or more existing controls. For example, if you need a control that encapsulates a button and a text box, you can create it by compiling the existing controls together.
• If an existing server control almost meets your requirements but lacks some required features, you can customize the control by deriving from it and overriding its properties, methods, and events.
• If none of the existing Web server controls (or their combinations) meet your requirements, you can create a custom control by deriving from one of the base control classes. These classes provide all the basic functionality of Web server controls, so you can focus on programming the features you need.

If none of the existing ASP.NET server controls meet the specific requirements of your applications, you can create either a Web user control or a Web custom control that encapsulates the functionality you need. The main difference between the two controls lies in ease of creation vs. ease of use at design time.
Web user controls are easy to make, but they can be less convenient to use in advanced scenarios. You develop Web user controls almost exactly the same way that you develop Web Forms pages. Like Web Forms, user controls can be created in the visual designer, they can be written with code separated from the HTML, and they can handle execution events. However, because Web user controls are compiled dynamically at run time they cannot be added to the Toolbox, and they are represented by a simple placeholder glyph when added to a page. This makes Web user controls harder to use if you are accustomed to full Visual Studio .NET design-time support, including the Properties window and Design view previews. Also, the only way to share the user control between applications is to put a separate copy in each application, which takes more maintenance if you make changes to the control.
Web custom controls are compiled code, which makes them easier to use but more difficult to create; Web custom controls must be authored in code. Once you have created the control, however, you can add it to the Toolbox and display it in a visual designer with full Properties window support and all the other design-time features of ASP.NET server controls. In addition, you can install a single copy of the Web custom control in the global assembly cache and share it between applications, which makes maintenance easier.

Web user controls	Web custom controls
Easier to create	Harder to create
Limited support for consumers who use a visual design tool	Full visual design tool support for consumers
A separate copy of the control is required in each application	Only a single copy of the control is required, in the global assembly cache
Cannot be added to the Toolbox in Visual Studio	Can be added to the Toolbox in Visual Studio
Good for static layout	Good for dynamic layout

7. Application and Session Events
   The ASP.NET page framework provides ways for you to work with events that can be raised when your application starts or stops or when an individual user's session starts or stops:
• Application events are raised for all requests to an application. For example, Application_BeginRequest is raised when any Web Forms page or XML Web service in your application is requested. This event allows you to initialize resources that will be used for each request to the application. A corresponding event, Application_EndRequest, provides you with an opportunity to close or otherwise dispose of resources used for the request.
• Session events are similar to application events (there is a Session_OnStart and a Session_OnEnd event), but are raised with each unique session within the application. A session begins when a user requests a page for the first time from your application and ends either when your application explicitly closes the session or when the session times out.

You can create handlers for these types of events in the Global.asax file.

8. Difference between ASP Session and ASP.NET Session?
   asp.net session supports cookie less session & it can span across multiple servers.
9. What is cookie less session? How it works?
   By default, ASP.NET will store the session state in the same process that processes the request, just as ASP does. If cookies are not available, a session can be tracked by adding a session identifier to the URL. This can be enabled by setting the following:
   
10. How you will handle session when deploying application in more than a server? Describe session handling in a webfarm, how does it work and what are the limits?
    By default, ASP.NET will store the session state in the same process that processes the request, just as ASP does. Additionally, ASP.NET can store session data in an external process, which can even reside on another machine. To enable this feature:
• Start the ASP.NET state service, either using the Services snap-in or by executing "net start aspnet_state" on the command line. The state service will by default listen on port 42424. To change the port, modify the registry key for the service: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aspnet_state\Parameters\Port
• Set the mode attribute of the section to "StateServer".
• Configure the stateConnectionString attribute with the values of the machine on which you started aspnet_state.

The following sample assumes that the state service is running on the same machine as the Web server ("localhost") and uses the default port (42424):

Note that if you try the sample above with this setting, you can reset the Web server (enter iisreset on the command line) and the session state value will persist.

11. What method do you use to explicitly kill a users session?Abandon()
12. What are the different ways you would consider sending data across pages in ASP (i.e between 1.asp to 2.asp)?Session, public properties
13. What is State Management in .Net and how many ways are there to maintain a state in .Net? What is view state?
    Web pages are recreated each time the page is posted to the server. In traditional Web programming, this would ordinarily mean that all information associated with the page and the controls on the page would be lost with each round trip.
    To overcome this inherent limitation of traditional Web programming, the ASP.NET page framework includes various options to help you preserve changes — that is, for managing state. The page framework includes a facility called view state that automatically preserves property values of the page and all the controls on it between round trips.
    However, you will probably also have application-specific values that you want to preserve. To do so, you can use one of the state management options.
    Client-Based State Management Options:
    View State
    Hidden Form Fields
    Cookies
    Query Strings
    Server-Based State Management Options
    Application State
    Session State
    Database Support
14. What are the disadvantages of view state / what are the benefits?
    Automatic view-state management is a feature of server controls that enables them to repopulate their property values on a round trip (without you having to write any code). This feature does impact performance, however, since a server control's view state is passed to and from the server in a hidden form field. You should be aware of when view state helps you and when it hinders your page's performance.
15. When maintaining session through Sql server, what is the impact of Read and Write operation on Session objects? will performance degrade?
    Maintaining state using database technology is a common practice when storing user-specific information where the information store is large. Database storage is particularly useful for maintaining long-term state or state that must be preserved even if the server must be restarted.
16. What are the contents of cookie?
17. How do you create a permanent cookie?
18. What is ViewState? What does the "EnableViewState" property do?Why would I want it on or off?
19. Explain the differences between Server-side and Client-side code?
    Server side code will process at server side & it will send the result to client. Client side code (javascript) will execute only at client side.
20. Can you give an example of what might be best suited to place in the Application_Start and Session_Start subroutines?