Search
Winners

Win Prizes

Social Presence
Twitter Twitter LinkedIn YouTube Google

Like us on Facebook
Advertisements
Ads

OOPS Interview Questions and Answers (99) - Page 1

Now you don't need go anywhere to get the best interview questions on Microsoft technology. We are trying to gather all real interview questions asked from MNCs and put them here. You can also assist us in doing so by submitting .net interview questions. These questions are generally different from certification questions however it may help you in that too.

99 records found.


Get 600+ .NET Interview preparation videos



Appear in Online Interview Test.


Page copy protected against web site content infringement by Copyscape

What is Polymorphisms?


Polymorphism means one interface and many forms. Polymorphism is a characteristics of being able to assign a different meaning or usage to something in different contexts specifically to allow an entity such as a variable, a function or an object to have more than one form.

There are two types of Polymorphism.
Compile time: function or operator overloading
Runtime: Inheritence & virtual functions

What is Abstract method?


Abstract method doesn't provide the implementation & forces the derived class to override the method.

What is Virtual method?


Virtual Method has implementation & provide the derived class with the option to override it.

Can Struct be inherited?


No, Struct can't be inherited as this is implicitly sealed.

What is Object?


Object is anything that is identifiable as a single material item.

What is Class?


A Class is the generic definition of what an object is a template.

The keyword class in C# indicates that we are going to define a new class (type of object)

What is Static field?


To indicate that a field should only be stored once no matter how many instance of the class we create.

What is Static Method?


It is possible to declare a method as Static provided that they don't attempt to access any instance data or other instance methods.

What is Inheritance?


It provides a convenient way to reuse existing fully tested code in different context thereby saving lot of coding.

Inheritance of classes in C# is always implementation Inheritance.

What is Virtual keyword?


This keyword indicates that a member can be overridden in a child class. It can be applied to methods, properties, indexes and events.

What is New modifiers?


The new modifiers hides a member of the base class. C# supports only hide by signature.

What is Abstract Class?


Abstract class is a class that can not be instantiated, it exists extensively for inheritance and it must be inherited. There are scenarios in which it is useful to define classes that is not intended to instantiate; because such classes normally are used as base-classes in inheritance hierarchies, we call such classes abstract classes.

Abstract classes cannot be used to instantiate objects; because abstract classes are incomplete, it may contain only definition of the properties or methods and derived classes that inherit this implements it's properties or methods.

Static, Value Types & interface doesn't support abstract modifiers. Static members cannot be abstract. Classes with abstract member must also be abstract.

For detailed example, read this article http://www.dotnetfunda.com/articles/article467-abstract-class--explained.aspx

What is Sealed modifiers?


Sealed types cannot be inherited & are concrete.
Sealed modifiers can also be applied to instance methods, properties, events & indexes. It can't be applied to static members.

Sealed members are allowed in sealed and non-sealed classes.

What is an Interface?


An interface is a contract & defines the requisite behavior of generalization of types.

An interface mandates a set of behavior, but not the implementation. Interface must be inherited. We can't create an instance of an interface.

An interface is an array of related function that must be implemented in derived type. Members of an interface are implicitly public & abstract.

An interface can inherit from another interface.

When to use Interface over abstract class?


Abstract Classes: Classes which cannot be instantiated. This means one cannot make a object of this class or in other way cannot create object by saying ClassAbs abs = new ClassAbs(); where ClassAbs is abstract class.
Abstract classes contains have one or more abstarct methods, ie method body only no implementation.
Interfaces: These are same as abstract classes only difference is we can only define method definition and no implementation.
When to use wot depends on various reasons. One being design choice.
One reason for using abstarct classes is we can code common
functionality and force our developer to use it. I can have a complete
class but I can still mark the class as abstract.
Developing by interface helps in object based communication.

What is pure virtual function?


When you define only function prototype in a base class without and do the complete implementation in derived class. This base class is called abstract class and client won’t able to instantiate an object using this base class.

A pure virtual function is a function that must be overridden in a derived class and need not be defined. A virtual function is declared to be "pure" using the curious "=0"
syntax:
class Base {
public:
void f1(); // not virtual
virtual void f2(); // virtual, not pure
virtual void f3() = 0; // pure virtual
};

Can we specify the access modifier for explicitly implemented interface method?


No, we can't specify the access modifier for the explicitly implemented interface method. By default its scope will be internal.

What is Protected access modifier in C#?


The protected keyword is a member access modifier. It can only be used in a declaring a function or method not in the class ie. a class can't be declared as protected class.

A protected member is accessible from within the class in which it is declared, and from within any class derived from the class that declare this member. In other words access is limited to within the class definition and any class that inherits from the class

A protected member of a base class is accessible in a derived class only if the access takes place through the derived class type.

For more details see http://msdn.microsoft.com/en-us/library/bcd5672a(VS.71).aspx

What is Public access modifier in C#?


The public keyword is an access modifier for types and type members ie. we can declare a class or its member (functions or methods) as Public. There are no restrictions on accessing public members.

What is Private access modifier in C#?


The private keyword is a member access modifier ie. we can't explicitly declare a class as Private, however if do not specify any access modifier to the class, its scope will be assumed as Private. Private access is the least permissive access level of all access modifiers.

Private members are accessible only within the body of the class or the struct in which they are declared. This is the default access modifier for the class declaration.

For more details, see http://msdn.microsoft.com/en-us/library/st6sy9xe(VS.71).aspx

Page:  1  2 3 4 5

More OOPS Exclusive Interview Questions & Answers here

Found this useful, bookmark this page to the blog or social networking websites. Page copy protected against web site content infringement by Copyscape

 Interview Questions and Answers Categories




Found interesting? Add this to: