What all is inherited from parent class in C++?

Following are the things that a derived class inherits from its parent:

• All the public and protected data members and member functions of the base class. Private members are not inherited.
• The assignment operator (=) of the base class.
• The type of the base class, which allows the derived class to be treated as a base class object when necessary.

Following are the properties which a derived class doesn’t inherit from its parent class: 

• Constructors and destructor: The constructors and destructor of a base class are not inherited by a derived class. However, the constructor of the base class can be invoked explicitly from the derived class constructor using the initialization list.
• Friend functions: The friend functions of a base class are not inherited by a derived class. Friend functions are those functions that have access to the private and protected members of a class.
• Overloaded operators: The overloaded operators of a base class are not inherited by a derived class. Overloaded operators are those operators that are redefined to perform specific operations on the objects of a class. However, a derived class can overload the operators that are inherited from its parent class.

Example 1: In this example, we will see how the derived class inherits from its parent.

C++

#include <iostream>
using namespace std;

// Parent class
class Vehicle {
public:
    int wheels;
    string color;
    void start() { cout << "Vehicle started." << endl; }
};

// Child class
class Car : public Vehicle {
public:
    string model;
    void drive()
    {
        cout << "Driving the " << color << " " << model
             << " car on " << wheels << " wheels." << endl;
    }
};

int main()
{
    // Create an object of the child class
    Car myCar;
    myCar.wheels = 4;
    myCar.color = "blue";
    myCar.model = "SUV";

    // Call functions from the parent and child classes
    myCar.start();
    myCar.drive();

    return 0;
}

Example 2: demonstration of the properties that a derived class doesn’t inherit from its parent class.

C++

#include <iostream>
using namespace std;

class Parent {
public:
    int parent_data;
    void parent_method()
    {
        cout << "This is a method in Parent class." << endl;
    }
    Parent()
    {
        cout << "Parent class constructor called." << endl;
    }
    ~Parent()
    {
        cout << "Parent class destructor called." << endl;
    }
};

class Child : public Parent {
public:
    int child_data;
    void child_method()
    {
        cout << "This is a method in Child class." << endl;
    }
};

int main()
{
    Child c;
    c.parent_data = 10;
    c.child_data = 20;
    cout << "Parent data: " << c.parent_data << endl;
    cout << "Child data: " << c.child_data << endl;
    c.parent_method();
    c.child_method();
    return 0;
}

Output:

Explanation: In this example, the Child class is derived from the Parent class. The Child class inherits the parent_data member and parent_method() function from the Parent class. However, the Child does not inherit the Parent class constructor, destructor, and friend functions.