Procedural to OOP

Encyclopedia : P : PR : PRO : Procedural to OOP

The following example uses C and C++ to demonstrate how Procedural program code could be translated to Object-Oriented program code.

Contents

0.0.1 Encapsulation

0.0.1.1 C code
0.0.1.2 Equivalent C++ code
0.0.1.3 Inference

0.0.2 Inheritance
0.0.3 Polymorphism

Encapsulation

C code

//////////////////////////////////////////////////////// // // // The following code uses a PROCEDURAL paradigm // // to calculate the area and perimeter of a circle. // // // ////////////////////////////////////////////////////////

#define PI 3.14159265359 #include

double circle_area(double r)

double circle_perimeter(double r)

int main()

Equivalent C++ code

In an Object-Oriented language like C++, we can create a circle class and encapsulate the same procedures within...

///////////////////////////////////////////////////////////
//                                                       //
//  The following code uses an OBJECT-ORIENTED paradigm  //
//  to calculate the area and perimeter of a circle.     //
//                                                       //
///////////////////////////////////////////////////////////


#define PI 3.14159265359
#include 
using namespace std;



class Circle
 // Encapsulated procedure
double circle_perimeter()       // Encapsulated procedure


public:
Circle(double r)                              // Constructor


double GetArea()                    // Public interface to find the area
double GetPerimeter()          // Public interface to find the perimeter
}



int main()

Inference

As can be seen from the example above the - procedural functions become the public or private method of class 'Circle' - the variables defined in main, global variables may become public or private variables in class 'Circle'

Inheritance

During 'Inheritance' one may declare common methods area(), perimeter() and variables in class 'shape' which may be parent of class circle, square and triangle etc.

Polymorphism

An array of 'shape' objects may, for example, contain objects of types 'circle', 'square' and 'triangle'

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