Hierarchical Inheritance in C++ Programming

Inheritance is the process of inheriting properties of objects of one class by objects of another class. The class which inherits the properties of another class is called Derived or Child or Sub class and the class whose properties are inherited is called Base or Parent or Super class. When more than one classes are derived from a single base class, such inheritance is known as Hierarchical Inheritance, where features that are common in lower level are included in parent class. Problems where hierarchy has to be maintained can be solved easily using this inheritance.

For example,

• Civil, Computer, Mechanical, Electrical are derived from Engineer.
• Natural language, Programming language are derived from Language.

Syntax of Hierarchical Inheritance

class base_classname
{
    properties;
    methods;
};

class derived_class1:visibility_mode base_classname
{
    properties;
    methods;
};

class derived_class2:visibility_mode base_classname
{
    properties;
    methods;
};
... ... ...
... ... ...
class derived_classN:visibility_mode base_classname
{
    properties;
    methods;
};

Example of Hierarchical Inheritance in C++

C++ program to create Employee and Student inheriting from Person using Hierarchical Inheritance

#include <iostream>
#include <conio.h>

using namespace std;

class person
{
    char name[100],gender[10];
    int age;
    public:
        void getdata()
        {
            cout<<"Name: ";
            fflush(stdin);  /*clears input stream*/
            gets(name);
            cout<<"Age: ";
            cin>>age;
            cout<<"Gender: ";
            cin>>gender;
        }
        void display()
        {
            cout<<"Name: "<<name<<endl;
            cout<<"Age: "<<age<<endl;
            cout<<"Gender: "<<gender<<endl;
        }
};

class student: public person
{
    char institute[100], level[20];
    public:
        void getdata()
        {
            person::getdata();
            cout<<"Name of College/School: ";
            fflush(stdin);
            gets(institute);
            cout<<"Level: ";
            cin>>level;
        }
        void display()
        {
            person::display();
            cout<<"Name of College/School: "<<institute<<endl;
            cout<<"Level: "<<level<<endl;
        }
};

class employee: public person
{
    char company[100];
    float salary;
    public:
        void getdata()
        {
            person::getdata();
            cout<<"Name of Company: ";
            fflush(stdin);
            gets(company);
            cout<<"Salary: Rs.";
            cin>>salary;
        }
        void display()
        {
            person::display();
            cout<<"Name of Company: "<<company<<endl;
            cout<<"Salary: Rs."<<salary<<endl;
        }
};

int main()
{
    student s;
    employee e;
    cout<<"Student"<<endl;
    cout<<"Enter data"<<endl;
    s.getdata();
    cout<<endl<<"Displaying data"<<endl;
    s.display();
    cout<<endl<<"Employee"<<endl;
    cout<<"Enter data"<<endl;
    e.getdata();
    cout<<endl<<"Displaying data"<<endl;
    e.display();
    getch();
    return 0;
}

Output

Student
Enter data
Name: John Wright
Age: 21
Gender: Male
Name of College/School: Abc Academy
Level: Bachelor

Displaying data
Name: John Wright
Age: 21
Gender: Male
Name of College/School: Abc Academy
Level: Bachelor

Employee
Enter data
Name: Mary White
Age: 24
Gender: Female
Name of Company: Xyz Consultant
Salary: $29000

Displaying data
Name: Mary White
Age: 24
Gender: Female
Name of Company: Xyz Consultant
Salary: $29000