Object Oriented Features (C++)

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Objects -

In structured programming language a problem is approached by dividing it into functions however in object-oriented programming the problem is divided into objects. An object is a component of a program that can have its own set of data and can be used to perform more than a repeated task. Designing the system with objects allowed developer to model system after the real world.

For Example – The developer has created an object of the student class to store data associated with a single student using member data and can perform certain operations using this object such as adding a new student, listing a student, checking whether a particular student record exist or not using the member functions of the class.

The object has been defined using the class name and object name with the following format –

void student_module()

{

      student student_record;                  

// ............CREATING THE OBJECT OF THE STUDENT CLASS.............

     

      char ch,che;

      int count = 0;

There are many candidates that are treated as objects in the system which are students, books, and administrator.

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Inheritance - 

As C++ allowed developer to create its own data types (classes) just like built in data types, C++ allowed the developer to use classes as building blocks of other classes using a concept called inheritance, new classes are built on top of the old ones. The new class referred to as a derived class, can inherit the data and functions of the original or the base class and can add its own data elements and functions.

For Example – The developer has designed a class named login as base class and inherited the class in the admin as well as student class as both student and admin need to login in the system. Data member for login class is a structure named login info having structure elements username and password, and a virtual member function system login. Both the admin and student class inherited login class and added its own data member’s admin name, structure student information etc.

The base class is inherited in the derived classes in following format –

Base Class –

class login

{

public:

            struct log_info{

                  int username;

                  char password[20];

            }log;

//__________PURE VIRTUAL FUNCTION______________ 

      virtual int system_login() = 0;    

     

};

Derived Classes –

class admin: public login          

//.........ADMIN CLASS INHERITING THE LOGIN CLASS..............

{

      private:

            char admin_name[20];

            char flag;

            fstream file;

      public:

            admin();

            int system_login(); //overriding

            void addrec();

};

class student: public login   //______INHERITANCE________

{

      public:

      struct student_information{

            char flag;

            int roll_number;

            char student_name[20];

            char course[20];

            char branch[16];

            int book_code;

            char issue_date[10], return_date[10];

            int fine;

            }b;

      private:

            fstream file;

      public:

            student();

            int system_login();

            void addrecUser();

            void addrec();

            void listrec();

            void delrec();

            void modrec();

            int check_record(int student_roll_number, int check_information);

            int check_exist( int student_roll_number);  //overloading 

            void Uprec();

            int  GetRoll();        

//______________FOR RANDOMLY GENERATING THE STUDENT ROLL NUMBER_____________

};

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