Introduction
In this blog we described about abstract class
in C#.
About Abstract Class
Abstract class is a special kind of class that
provides the default functionality to their subclasses. Abstract class can not
me instantiated means we can not create the instance of abstract class but
abstract class can be implemented in their subclasses. Abstract classes can have
abstract functions or non abstract functions. a abstract class which have a
"abstract" keyword in a function it does not provide the implementation of that
function in abstract class. The implementation and logic of abstract method is
provided in subclasses. Subclasses use "override" keyword with same method name
(as abstract method name) to provide further implementation of abstract methods.
Use the Abstract modifier
in a class declaration to indicate that a class is intended only to be a base
class of other classes. Members marked as abstract, or included in an abstract
class, must be implemented by classes that derive from the abstract class.
Features of Abstract Class
- An abstract class can not be
instantiated.
- An abstract class may contain abstract
method and non abstract methods.
-
Abstract classes are designed to be used as base classes for
other abstract and non-abstract classes.
Abstract Method
Abstract methods are part of abstract class. If the abstract
class contains any methods with keyword as abstract then such methods are termed
as abstract methods. When a class inherits from an abstract class, the derived
class must implement all the abstract methods of the abstract class.
An abstract method is
a method that is declared without an implementation (without braces, and
followed by a semicolon), like this:
public
abstract
int
multiplication(int
num1,
int
num2);
//abstract method
Features of Abstract Method
-
An abstract method must be override in child classes.
-
An abstract method does not have implementation detail
in abstract class.
-
Only abstract class can have abstract method.
using
System;
namespace
ConsoleApplication1
{
abstract
class
myclass
{
public
int
addfunction(int
num1,int
num2)
//non abstract method
{
return
(num1 + num2);
}
public
abstract
int
multiplication(int
num1,
int
num2);
//abstract method
}
class
Program:myclass
{
public
override
int
multiplication(int
n1,
int
n2)
{
return
(n1 * n2);
}
static
void
Main(string[]
args)
{
Program
obj =
new
Program();
Console.WriteLine("Enter
First Number:");
int
n1 =
Convert.ToInt16(Console.ReadLine());
Console.WriteLine("Enter
Second Number:");
int
n2 =
Convert.ToInt16(Console.ReadLine());
int
add = obj.addfunction(n1, n2);
Console.WriteLine("Addition
is {2} of First Number{0}, Second Number {1}"
, n1,n2, add);
Console.ReadLine();
int
mul = obj.multiplication(n1, n2);
Console.WriteLine("Multiplication
is {2} of First Number {0}, Second Number {1}",
n1, n2, mul);
Console.ReadLine();
}
}
}
Output
Pass two numbers as shown below.
![FIG1.jpg]()
Result of Addition & Multiplication of numbers.
![FIG2.jpg]()
Summary
An abstract class is a class that you cannot create an instance
of. It can provide basic functionality, but in order for that functionality to
be used, one or more other classes must derive from the abstract class. One of
the major benefits of abstract classes is that you can reuse code without having
to retype it.