.net technology using C#

1. DEPARTMENT OF COMPUTER SCIENCE AND APPLICATIONS
BABA GHULAM SHAH BADSHAH UNIVERSITY RAJOURI
NAME:-lucky
ROLL NO. -------MCS-20-----
PRESENTATION TOPIC:- Abstract Class, Interface
PRESENTED TO:- Mr. -------
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2. Contents:
 Abstract Class
 Interface
 Implementing Interface
 Extending Interface
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3. ABSTRACT CLASS
 Abstract classes are one of the essential behaviors
provided by .NET.
 Commonly, we would like to make classes that only
represent base classes, and don’t want anyone to
create objects of these class types.
 We can make use of abstract classes to implement
such functionality in C# using the modifier 'abstract'.
 An abstract class means that, no object of this class
can be instantiated, but can make derivations of
this.
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4. FEATURES:
 An abstract class can inherit from a class and one
or more interfaces.
 An abstract class can implement code with non-
Abstract methods.
 An Abstract class can have modifiers for methods,
properties etc.
 An Abstract class can have constants.
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5. CONT.….
 An abstract class cannot be instantiated.
 An abstract class contain abstract members as well
as non- abstract members.
 An abstract class cannot be sealed class because
the sealed modifier prevents a class from being
inherited and the abstract modifier requires a class
to be inherited.
 An abstract class can have constructors or
destructors.
 An abstract class cannot support multiple
inheritance.
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6. DECLARATION OF ABSTRACT CLASS
 abstract class ab
{…
… }
 An abstract class can contain either abstract
methods or non abstract methods.
 Abstract members do not have any implementation
in the abstract class, but the same has to be
provided in its derived class.
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7. WHAT AN INTERFACE IS?
 In the real world, an interface means a medium to
interact with something.
 To be precise, it's a point where two systems,
subjects, organizations and so on meet and
interact.
 Similarly, in the programming world, an interface
means a contract to interact with multiple code
modules.
 If a class wants to communicate with an interface, it
must implement it and define its members.
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8. PROGRAM
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OUTPUT
Added is 30
Multiplication iss 200

9. INTERFACE
 Interfaces define properties, methods, and events,
which are the members of the interface.
 Interfaces contain only the declaration of the
members.
 It is the responsibility of the deriving class to define
the members.
 It often helps in providing a standard structure that
the deriving classes would follow.
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10. Cont..
 An interface is a purely logical construct that describes
functionality without specifying implementation
 An interface generally defines set of methods that will
be implemented by the class
 But interface doesn’t implement any method itself
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11. DECLARING INTERFACES
 Interfaces are declared using the interface keyword.
 It is similar to class declaration.
 Interface statements are public by default.
Following is an example of an interface
declaration:
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12. IMPLEMENTING INTERFACES
 Interfaces are used as ‘superclasses’ whose
properties are inherited by classes.
 It is therefore necessary to create a class that
inherits the given interface.
class classname : interfacename
body of classname

13. EXTENDING AN INTERFACE
 Like classes, interfaces can also be extended. That
is, an interface can be subinterfaced from other
interfaces.
 The new subinterface will inherit all the members of
the superinterface in the manner similar to
subclasses.
interface name2 : name1
members of name2

14. EXAMPLE 1
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15. OUTPUT
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16. EXAMPLE 2
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17. CLASS IMPLEMENT INTERFACE
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18. OUTPUT
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19. DIFFERENCES
Interface
 Contains only signatures
 Cannot contain
implementations
 Cannot contain
constructor
 A class can implement
multiple interface
Abstract class
 Can contains signatures
 Can contain
implementations
 Can contain constructor
 A class can implement
only one
abstract class
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