Abstract class in C#

Amit Maheshwari

Hi friends,

I want to know that why do we make a class an abstract? What are the benefits to do that please explain in programming scenario?

5 Replies

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lakshmipathi vemula14y ago
Hello Frnd, If you want to learn Best Object Orientation Concepts in C#.Net ,follow the link.
This will explain you about Abstract classes in c#.NET
Link:http://www.bestdotnettraining.com/Online/Training/CSharp/Inheritance/6
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Senthilkumar14y ago
Hi,

(Referred from MSDN)

The abstract modifier can be used with classes, methods, properties, indexers, and events.

Use the abstract modifier in a class declaration to indicate that a class is intended only to be a base class of other classes.

Abstract classes have the following features:

An abstract class cannot be instantiated.
An abstract class may contain abstract methods and accessors.
It is not possible to modify an abstract class with the sealed modifier, which means that the class cannot be inherited.
A non-abstract class derived from an abstract class must include actual implementations of all inherited abstract methods and accessors.
Use the abstract modifier in a method or property declaration to indicate that the method or property does not contain implementation.

Abstract methods have the following features:

An abstract method is implicitly a virtual method.
Abstract method declarations are only permitted in abstract classes.
Because an abstract method declaration provides no actual implementation, there is no method body; the method declaration simply ends with a semicolon and there are no braces ({ }) following the signature. For example:
public abstract void MyMethod();
The implementation is provided by an overriding method, which is a member of a non-abstract class.
It is an error to use the static or virtual modifiers in an abstract method declaration.
Abstract properties behave like abstract methods, except for the differences in declaration and invocation syntax.

It is an error to use the abstract modifier on a static property.
An abstract inherited property can be overridden in a derived class by including a property declaration that uses the override modifier.
An abstract class must provide implementation for all interface members.

An abstract class that implements an interface might map the interface methods onto abstract methods.

The same you can refer in the following:
http://msdn.microsoft.com/en-us/library/sf985hc5(v=vs.71).aspx
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Lars Persson14y ago
Lets say you have a class "Vehicle"

From that class you can let other classes inherit.

You can make a Car-class, Truck-Class, Bus-class etc.

The thing is, that nothing is only a vehicle, it is always some kind of vehicle.

So it makes no sense in creating an object of type vehicle.

That´s why you make it abstract, so you can´t create any objects of it.
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Keyur Narkhi14y ago
Hi amit

Abstract classes are one,in which you can not create the object of that class.And you can create the abstract method which needs to override into your child classes.

When you need to define common behavior ,you can go with abstract class.

Please follow this url

http://www.c-sharpcorner.com/UploadFile/rajeshvs/AbstractClassesNMethods11122005014357AM/AbstractClassesNMethods.aspx

Hope this helps.
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MuthuMari M14y ago
Hi,

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.

pls refer this url for samples.

http://en.csharp-online.net/Interfaces_and_Abstract_Classes

http://msdn.microsoft.com/en-us/library/sf985hc5%28v=vs.71%29.aspx

thanks.

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