25. How has exception handling changed in .NET Framework 4.0?
In .NET 4.0, a new namespace, System.Runtime.ExceptionServices, has been introduced which contains the following classes for handling exceptions in a better and advanced manner:
HandleProcessCorruptedStateExceptionsAttribute Class – Enables managed code to handle the corrupted state exceptions that occur in an operating system. These exceptions cannot be caught by specifying the try…catch block. To handle such exceptions, you can apply this attribute to the method that is assigned to handle these exceptions.
FirstChanceExceptionEventArgs Class – Generates an event whenever a managed exception first occurs in your code, before the common language runtime begins searching for event handlers.
26. What is a delegate?
A delegate is similar to a class that is used for storing the reference to a method and invoking that method at runtime, as required. A delegate can hold the reference of only those methods whose signatures are same as that of the delegate. Some of the examples of delegates are type-safe functions, pointers, or callbacks.
27. What is the syntax to inherit from a class in C#?
When a class is derived from another class, then the members of the base class become the members of the derived class. The access modifier used while accessing members of the base class specifies the access status of the base class members inside the derived class.
The syntax to inherit a class from another class in C# is as follows:
class MyNewClass : MyBaseclass
28. State the features of an interface.
An interface is a template that contains only the signature of methods. The signature of a method consists of the numbers of parameters, the type of parameter (value, reference, or output), and the order of parameters. An interface has no implementation on its own because it contains only the definition of methods without any method body. An interface is defined using the interface keyword. Moreover, you cannot instantiate an interface. The various features of an interface are as follows:
An interface is used to implement multiple inheritance in code. This feature of an interface is quite different from that of abstract classes because a class cannot derive the features of more than one class but can easily implement multiple interfaces.
It defines a specific set of methods and their arguments.
Variables in interface must be declared as public, static, and final while methods must be publicand abstract.
A class implementing an interface must implement all of its methods.
An interface can derive from more than one interface.
29. Can you use the ‘throws’ clause to raise an exception?
No, the throws clause cannot be used to raise an exception. The throw statement signals the occurrence of an exception during the execution of a program. When the program encounters a throw statement, the method terminates and returns the error to the calling method.
30. Define an array.
An array is defined as a homogeneous collection of elements, stored at contiguous memory locations, which can be referred by the same variable name. All the elements of an array variable can be accessed by index values. An Index value specifies the position of a particular element in an array variable.
