C++ Program to Implement Single Inheritance

Introduction

Inheritance is one of the core principles of object-oriented programming (OOP). It allows us to create a new class that reuses, extends, or modifies the behavior defined in another class. Single inheritance is the simplest form of inheritance where a class inherits from only one base class. In this article, we will explore how to code a C++ Program to Implement Single Inheritance. We’ll walk through the necessary prerequisites, examine various examples, and provide detailed explanations for each approach.

Prerequisites

Before diving into the code, it’s essential to have a basic understanding of:

1. C++ Programming Language: Familiarity with basic syntax, classes, and objects.
2. Object-Oriented Programming (OOP): Understanding of fundamental OOP concepts like inheritance, encapsulation, and polymorphism.
3. Standard Library Functions: Knowledge of C++ Standard Library functions and header files.

With these prerequisites in mind, let’s explore different ways to implement single inheritance using C++.

Example 1: Basic Single Inheritance in C++

Code Explanation

In this example, we will create a simple Person class and a derived Student class that inherits from Person.

Code

#include <iostream>
#include <string>
using namespace std;

class Person {
public:
    string name;
    int age;

    void displayPersonInfo() {
        cout << "Name: " << name << ", Age: " << age << endl;
    }
};

class Student : public Person {
public:
    int studentID;

    void displayStudentInfo() {
        displayPersonInfo();
        cout << "Student ID: " << studentID << endl;
    }
};

int main() {
    Student student;
    student.name = "Alice";
    student.age = 20;
    student.studentID = 12345;

    student.displayStudentInfo();

    return 0;
}

Output

Name: Alice, Age: 20
Student ID: 12345

Explanation

In this example, the Student class inherits from the Person class. This allows the Student class to access the properties and methods of the Person class. The displayStudentInfo method in the Student class calls the displayPersonInfo method to display the inherited properties.

Example 2: Extending Functionality in Derived Class

Code Explanation

In this example, we will extend the functionality of the base class by adding new methods in the derived class.

Code

#include <iostream>
#include <string>
using namespace std;

class Person {
public:
    string name;
    int age;

    void displayPersonInfo() {
        cout << "Name: " << name << ", Age: " << age << endl;
    }
};

class Employee : public Person {
public:
    int employeeID;
    double salary;

    void displayEmployeeInfo() {
        displayPersonInfo();
        cout << "Employee ID: " << employeeID << ", Salary: " << salary << endl;
    }

    void setSalary(double newSalary) {
        salary = newSalary;
    }
};

int main() {
    Employee employee;
    employee.name = "Bob";
    employee.age = 35;
    employee.employeeID = 67890;
    employee.salary = 50000.0;

    employee.displayEmployeeInfo();
    employee.setSalary(55000.0);
    cout << "Updated Salary: " << employee.salary << endl;

    return 0;
}

Output

Name: Bob, Age: 35
Employee ID: 67890, Salary: 50000
Updated Salary: 55000

Explanation

In this example, the Employee class inherits from the Person class and adds new properties and methods. The setSalary method allows the salary to be updated, showcasing how the derived class can extend the functionality of the base class.

Example 3: Overriding Methods in Derived Class

Code Explanation

In this example, we will demonstrate method overriding by redefining a method in the derived class.

Code

#include <iostream>
#include <string>
using namespace std;

class Person {
public:
    string name;
    int age;

    virtual void displayInfo() {
        cout << "Name: " << name << ", Age: " << age << endl;
    }
};

class Teacher : public Person {
public:
    string subject;

    void displayInfo() override {
        cout << "Name: " << name << ", Age: " << age << ", Subject: " << subject << endl;
    }
};

int main() {
    Teacher teacher;
    teacher.name = "Charlie";
    teacher.age = 45;
    teacher.subject = "Mathematics";

    teacher.displayInfo();

    return 0;
}

Output

Name: Charlie, Age: 45, Subject: Mathematics

Explanation

In this example, the Teacher class inherits from the Person class and overrides the displayInfo method. The override keyword is used to ensure that the method in the derived class is intended to override the base class method. This demonstrates polymorphism, where the same method name can have different implementations in different classes.

Conclusion

Single inheritance in C++ is a powerful tool for creating a class hierarchy where a derived class inherits the properties and methods of a base class. Through the examples provided, we’ve seen different ways to implement single inheritance, including basic inheritance, extending functionality, and method overriding.