38.What is difference between constants, readonly and, static ?

• Constants: The value can’t be changed.
• Read-only: The value will be initialized only once from the constructor of the class. 
• Static: Value can be initialized once.

 39.What are the different types of statements supported in C#?

C# supports several different kinds of statements are

• Block statements
• Declaration statements
• Expression statements
• Selection statements
• Iteration statements
• Jump statements
• Try catch statements
• Checked and unchecked 
• Lock statement

  

40.What is an interface class?

It is an abstract class with public abstract methods all of which must be implemented in the inherited classes.

41.what are value types and reference types?

 Value types are stored in the Stack.
Examples : bool, byte, chat, decimal, double, enum , float, int, long, sbyte, short, strut, uint, ulong, ushort.

Reference types are stored in the Heap.
Examples : class, delegate, interface, object, string.

42.What is the difference between string keyword and System.String class?

String keyword is an alias for Syste.String class. Therefore, System.String and string keyword are the same, and you can use whichever naming convention you prefer. The String class provides many methods for safely creating, manipulating, and comparing strings.

43.What are the two data types available in C#?

• Value type 
• Reference type

44.What are the different types of Caching?

There are three types of Caching :

• Output Caching: stores the responses from an asp.net page.
• Fragment Caching: Only caches/stores the portion of page (User Control) 
• Data Caching: is Programmatic way to Cache objects for performance.

 45.What is the difference between Custom Control and User Control?

Custom Controls are compiled code (Dlls), easier to use, difficult to create, and can be placed in toolbox. Drag and Drop controls. Attributes can be set visually at design time. Can be used by Multiple Applications (If Shared Dlls), Even if Private can copy to bin directory of web application add reference and use. Normally designed to provide common functionality independent of consuming Application.

User Controls are similar to those of ASP include files, easy to create, can not be placed in the toolbox and dragged - dropped from it. A User Control is shared among the single application files

46.What is methods?

A method is a member that implements a computation or action that can be performed by an object or class. Static methods are accessed through the class. Instance methods are accessed through instances of the class.

47.What is fields?

A field is a variable that is associated with a class or with an instance of a class.

48.What is events?

An event is a member that enables a class or object to provide notifications. An event is declared like a field except that the declaration includes an event keyword and the type must be a delegate type.

49.What is literals and their types?

Literals are value constants assigned to variables in a program. C# supports several types of literals are

• Integer literals
• Real literals
• Boolean literals
• Single character literals
• String literals 
•  Backslash character literals 

 50.What is the difference between value type and reference type?

• Value types are stored on the stack and when a value of a variable is assigned to another variable. 
• Reference types are stored on the heap, and when an assignment between two reference variables occurs.

                

51.What are the features of c#?

• C# is a simple and powerful programming language for writing enterprise edition applications.
• This is a hybrid of C++ and VB. It retains many C++ features in the area statements,expressions, and operators and incorporated the productivity of VB.
• C# helps the developers to easily build the web services that can be used across the Internet through any language, on any platform.
• C# helps the developers accomplishing with fewer lines of code that will lead to the fewer errors in the code. 
• C# introduces the considerable improvement and innovations in areas such as type safety,versioning. events and garbage collections.

  52.What are the types of errors?

• Syntax error
• Logic error 
• Runtime error

 53.What is the difference between break and continue statement?

The break statement is used to terminate the current enclosing loop or conditional statements in which it appears. We have already used the break statement to come out of switch statements.
The continue statement is used to alter the sequence of execution. Instead of coming out of the loop like the break statement did, the continue statement stops the current iteration and simply returns control back to the top of the loop. 

54.Define namespace?

The namespace are known as containers which will be used to organize the hierarchical set of .Net classes.

55.What is a code group?

A code group is a set of assemblies that share a security context.

56.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.

57.What is the difference between static and instance methods?

A method declared with a static modifier is a static method. A static method does not operate on a specific instance and can only access static members.

A method declared without a static modifier is an instance method. An instance method operates on a specific instance and can access both static and instance members. The instance on which an instance method was invoked can be explicitly accessed as this. It is an error to refer to this in a static method. 

58.What are the different types of variables in C#?

Different types of variables used in C# are :

• static variables
• instance variable
• value parameters
• reference parameters
• array elements
• output parameters 
• local variables

59.What is meant by method overloading?

Method overloading permits multiple methods in the same class to have the same name as long as they have unique signatures. When compiling an invocation of an overloaded method, the compiler uses overload resolution to determine the specific method to invoke

60.What is parameters?

Parameters are used to pass values or variable references to methods. The parameters of a method get their actual values from the arguments that are specified when the method is invoked. There are four kinds of parameters: value parameters, reference parameters, output parameters, and parameter arrays. 

61.Is C# is object oriented?

YEs, C# is an OO langauge in the tradition of Java and C++.

62.What is the difference between Array and Arraylist?

An array is a collection of the same type. The size of the array is fixed in its declaration. A linked list is similar to an array but it doesn’t have a limited size. 

63.What are the special operators in C#?

C# supports the following special operators.

• is (relational operator)
• as (relational operator)
• typeof (type operator)
• sizeof (size operator)
• new (object creator)
• .dot (member access operator)
• checked (overflow checking) 
• unchecked (prevention of overflow checking)

64.What is meant by operators in c#?

An operator is a member that defines the meaning of applying a particular expression operator to instances of a class. Three kinds of operators can be defined: unary operators, binary operators, and conversion operators. All operators must be declared as public and static. 

65.What is a parameterized type?

A parameterized type is a type that is parameterized over another value or type.

66.What are the features of abstract class?

• An abstract class cannot be instantiated, and it is an error to use the new operator on an abstract class.
• An abstract class is permitted (but not required) to contain abstract methods and accessors. 
• An abstract class cannot be scaled.

 67.What is the use of abstract keyword?

The modifier abstract is a keyword used with a class, to indicate that this class cannot itself have direct instances or objects, and it is intended to be only a 'base' class to other classes. 

68.What is the use of goto statement?

The goto statement is also included in the C# language. This goto can be used to jump from inside a loop to outside. But jumping from outside to inside a loop is not allowed.

69What is the difference between console and window application?

• A console application, which is designed to run at the command line with no user interface. 
• A Windows application, which is designed to run on a user’s desktop and has a user interface.

 70.What is the use of return statement?

The return statement is associated with procedures (methods or functions). On executing the return statement, the system passes the control from the called procedure to the calling procedure. This return statement is used for two purposes :

·  to return immediately to the caller of the currently executed code

·  to return some value to the caller of the currently executed code.

71.What is the difference between Array and LinkedList?

Array is a simple sequence of numbers which are not concerned about each others positions. they are independent of each others positions. adding,removing or modifying any array element is very easy. Compared to arrays ,linked list is a comlicated sequence of numbers. 

72.Does C# have a throws clause?

No, unlike Java, C# does not require the developer to specify the exceptions that a method can throw.

73.Does C# support a variable number of arguments?

Yes, uisng the params keyword. The arguments are specified as a list of arguments of a specific type.

74.Can you override private virtual methods?

No, private methods are not accessible outside the class.

75What is a multi cast delegates?

It is a delegate that points to and eventually fires off several methods.