What is inheritance in D programming?
What is inheritance?
Inheritance is an object oriented programming concept that allows other classes to use the properties and method of a class. In D programming, the class inherited is the base class and the class inheriting is the derived class. Let’s see an example.
Code
import std.stdio;// Base classclass Shape {public:void dimension(int h,int w) {height = h;width = w;}int width;int height;}// Derived classclass Square: Shape {public:int findArea() {return (width * height);}}void main() {Square Sqr = new Square();Sqr.dimension(9,9);// Print the area of the object.writeln("Total area of square: ", Sqr.findArea());}
Explanation
In the example above, we create an object of the base class, Shape, to take dimensions. We also create an object of the derived class, Square, to calculate the area.
-
Line 3: We define the base class,
shape. -
Line 4: We make it publicly accessible by adding the
publickeyword. -
Lines 5–8: We declare a method,
dimension(), to receive the square’s dimensions. -
Line 9 and 10: We define the variable we would use to make the area calculation.
-
Line 13: We create our derived class to inherit the base class. Notice the
:used after the name of the derived class. -
Line 14: We make it publicly accessible by adding the
publickeyword. -
Lines 15–18: We declare a method,
findArea(), to calculate the square’s area. -
Line 20: We instantiate the derived class to a
Sqrvariable. -
Line 21: We access the
dimension()method of the base class, where we passed the square’s values. -
Line 23: We finally call the
Sqr.findArea()to output the calculation’s result.
