Multiple Inheritance

A class can inherit more than one class. In such a case, all members of all inherited classes will become members of the derived class. Given the classes ClassA and ClassB, a class ClassC can be defined as inheriting both: 
class ClassA{};

class ClassB {};

class ClassC: public ClassA, public ClassB {};
In the program below, a class Person is declared, then a class StateEmployee is declared. Finally a third class called Teacher, derived both from Person and StateEmployee is declared. All members of Person and all members of StateEmployee become members of Teacher. A Teacher object will contain name, age, setNameAge(), printNameAge(), from Person and socialSecurityNr, setSocialSEcurityNr(), printSocialSEcurityNr(), from StateEmployee. Further, it will contain subject, setSubject() and printSubject(). All members of Teacher inherited from its base classes will retain their visibility level, as a result of the Teacher declaration, in which public comes before both of the inherited classes: 
class Teacher: public Person, public StateEmployee


Example


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

// Base class
class Person
{
     string name;
     int age;
public:
     void setNameAge(string aName, int anAge)
     {
           name = aName;
           age = anAge;
     }

     void printNameAge()
     {
           cout << "name: " << name << ", age: " << age << "\n";
     }
};

// Base class
class StateEmployee
{
int socialSecurityNr;
public:
     void setSocialSEcurityNr(int nr)
     {
        socialSecurityNr = nr;
     }

     void printSocialSEcurityNr()
     {
           cout << "SSN: " << socialSecurityNr << "\n";
     }
};

// Teacher is derived from Person and StateEmployee
class Teacher : public Person, public StateEmployee
{
     string subject;
public:
     void setSubject(string aSubject)
     {
           subject = aSubject;
     }

     void printSubject()
     {
           cout << "subject is: " << subject << "\n";
     }
};

int main()
{

     Teacher teacher;
     teacher.setSubject("Math");
     teacher.setNameAge("Tony", 43);
     teacher.setSocialSEcurityNr(1234);
     teacher.setSubject("English");
     teacher.printNameAge();
     teacher.printSocialSEcurityNr();
     teacher.printSubject();
}

Output

name: Tony, age: 43
SSN: 1234
subject is: English