using namespace std;

/*

This is a complete example!
        - A base class "Animal"
        - subclass "Human"
        - subclass "Pet"

We set up an array of four Animals in a test program (2
humans and 2 pets) and then we loop thought them, reporting
the age (which is implemented ONCE in the base class because
it's common code) and the name (which is implemented in each
subclass, because it differs between humans and pets)

Compile and load line:

g++ -o first_i first_inheritance.cpp

Take a deep breath. It's unusual to do this in one file. It
would normally be in ... 7
        3 files of headers, one for each class
        3 files of source, one for each class
        and the test program (a.k.a. the application)
You would compile each of the four sources separately, pulling
in the correct headers via #includes, and you would use #ifndefs
to avoid duplicate loading. That will be our next example.

*/

#include <iostream>

// Define the API to the classes
// -----------------------------

// Common things in "animal"

/* Note the "virtual" declaration which says that every
animal has a name, but it will be handled differently
depending on the type of animal. (The {} pair is VITAL!) */

class Animal {
        public:
                Animal(int age);
                int getAge();
                virtual char *getName() {};
        protected:
                int age;
};

// Specifics in "human" and "pet"

class Human : public Animal {
        public:
                Human(char *forename, char *surname, int age);
                char *getName();
        protected:
                char *forename;
                char *surname;
};

class Pet : public Animal {
        public:
                Pet(char *name, int age, char *breed, int weight);
                char *getName();
        protected:
                char *name;

};

// Define the classes themselves
// -----------------------------

Animal::Animal(int age) {
        this->age = age;
        }

int Animal::getAge() {
        return this->age;
        }

// Note that the Human constructor calls the Animal constructor ...

Human::Human(char *forename, char *surname, int age) : Animal (age){
        this->forename = forename;
        this->surname = surname;
        }

Pet::Pet(char *name, int age, char *breed, int weight): Animal (age) {
        this->name = name;
        }

char *Human::getName() {
        // Should really concat strings but this is an inheritance
        // demo and not a string one!
        return "Mrs Smith";
        }

char *Pet::getName() {
        return this->name;
        }

// Main test program
// -----------------

int main () {

        // Set up object pointer array for the underlying base class

        Animal * Ourhouse [4];
        int k;

        // Set up objects that are animals within that array
        // even if they are specialised types of animal

        Ourhouse[0] = new Human("Lisa","Ellis",21);
        Ourhouse[1] = new Human("Graham","Ellis",55);
        Ourhouse[2] = new Pet("Gypsy",4,"Dog",30);
        Ourhouse[3] = new Pet("Charlie",13,"Cat",3);

        // Loop through the animals and get their names, even
        // through that will be done differenly for pets and humans

        for (k=0; k<4; k++) {
                char * Name = Ourhouse[k]->getName();
                int years = Ourhouse[k]->getAge();
                cout << "Living there ... " << Name
                        << " aged " << years << endl;
                }

        return 0;
        }

/* Sample Output

wizard:cpp graham$ ./first_i
Living there ... Mrs Smith aged 21
Living there ... Mrs Smith aged 55
Living there ... Gypsy aged 4
Living there ... Charlie aged 13
wizard:cpp graham$

*/