C++ OO Multiple Inheritance

Multiple inheritance is a feature in C++ that allows a class to inherit from more than one base class. This means that the derived class can have access to all the members of the base classes that it inherits from.

The need for multiple inheritance arises when a derived class needs to inherit functionality from more than one base class. For example, suppose you want to create a class that represents a square shape in both two-dimensional and three-dimensional space. You could have a base class for two-dimensional shapes and another base class for three-dimensional shapes. By using multiple inheritance, you can create a derived class that inherits from both of these base classes and has access to the functionality of both.

Multiple inheritance can also be used to create a hierarchy of classes with different levels of specialization. 

#include <iostream>

using namespace std;

class First{
    public:
        string name = "Jordan";

        void printName() {
            cout << "Name: " << name  << endl;
        }
};

class Second{
    public:
        string last_name = "Peterson";

        void printLastName() {
            cout << "Last Name: " << last_name << endl;
        }

};

class Third : public First, Second {
    public:
        void caller() {
            printName();
            printLastName();
        }
};

int main() {

    Third Object;
    Object.caller();

    return 0;
}

In this code, the classes First and Second are being inherited publicly by the class Third, which means that the public and protected members of First and Second will be accessible by the objects of Third.

Third class has a member function caller() which calls the member functions of both the base classes, First and Second. The printName() and printLastName() functions of the First and Second classes respectively are being called using the object of the Third class. 

int main() {

    Third Object;
    Object.caller();

    First Obj_1;
    Obj_1.printName();

    Second Obj_2;
    Obj_2.printLastName();

    return 0;
}

We have created three objects of three different classes.

The first object Object is of the class Third, which inherits from both First and Second classes. Object calls the caller function, which in turn calls printName function from First class and printLastName function from Second class. Therefore, when Object.caller() is executed, it prints out both the name and the last name.

The second object Obj_1 is of the class First, and we call the printName function of First class, which simply prints out the name variable.

The third object Obj_2 is of the class Second, and we call the printLastName function of Second class, which simply prints out the last_name variable.

So, in summary, we are able to create objects of different classes and call their respective member functions, and in case of Third class object, it is able to call member functions of both First and Second classes because it inherits from both of them.