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            : Worker(wk), Waiter(wk,p), Singer(wk,v) {}

    SingingWaiter(const Waiter & wt, int v = other)

            : Worker(wt),Waiter(wt), Singer(wt,v) {}

    SingingWaiter(const Singer & wt, int p = 0)

            : Worker(wt),Waiter(wt,p), Singer(wt) {}

    void Set();

    void Show() const;

};

#endif

Listing 14.11. workermi.cpp

// workermi.cpp -- working class methods with MI

#include "workermi.h"

#include

using std::cout;

using std::cin;

using std::endl;

// Worker methods

Worker::~Worker() { }

// protected methods

void Worker::Data() const

{

    cout << "Name: " << fullname << endl;

    cout << "Employee ID: " << id << endl;

}

void Worker::Get()

{

    getline(cin, fullname);

    cout << "Enter worker's ID: ";

    cin >> id;

    while (cin.get() != '\n')

        continue;

}

// Waiter methods

void Waiter::Set()

{

    cout << "Enter waiter's name: ";

    Worker::Get();

    Get();

}

void Waiter::Show() const

{

    cout << "Category: waiter\n";

    Worker::Data();

    Data();

}

// protected methods

void Waiter::Data() const

{

    cout << "Panache rating: " << panache << endl;

}

void Waiter::Get()

{

    cout << "Enter waiter's panache rating: ";

    cin >> panache;

    while (cin.get() != '\n')

        continue;

}

// Singer methods

char * Singer::pv[Singer::Vtypes] = {"other", "alto", "contralto",

            "soprano", "bass", "baritone", "tenor"};

void Singer::Set()

{

    cout << "Enter singer's name: ";

    Worker::Get();

    Get();

}

void Singer::Show() const

{

    cout << "Category: singer\n";

    Worker::Data();

    Data();

}

// protected methods

void Singer::Data() const

{

    cout << "Vocal range: " << pv[voice] << endl;

}

void Singer::Get()

{

    cout << "Enter number for singer's vocal range:\n";

    int i;

    for (i = 0; i < Vtypes; i++)

    {

        cout << i << ": " << pv[i] << "   ";

        if ( i % 4 == 3)

            cout << endl;

    }

    if (i % 4 != 0)

        cout << '\n';

    cin >>  voice;

    while (cin.get() != '\n')

        continue;

}

// SingingWaiter methods

void SingingWaiter::Data() const

{

    Singer::Data();

    Waiter::Data();

}

void SingingWaiter::Get()

{

    Waiter::Get();

    Singer::Get();

}

void SingingWaiter::Set()

{

    cout << "Enter singing waiter's name: ";

    Worker::Get();

    Get();

}

void SingingWaiter::Show() const

{

    cout << "Category: singing waiter\n";

    Worker::Data();

    Data();

}

Of course, curiosity demands that you test these classes, and Listing 14.12 provides code to do so. Note that the program makes use of polymorphism by assigning the addresses of various kinds of classes to base-class pointers. Also the program uses the C-style string library function strchr() in the following test:

while (strchr("wstq", choice) == NULL)

This function returns the address of the first occurrence of the choice character value in the string "wstq"; the function returns the NULL pointer if the character isn’t found. This test is simpler to write than an if statement that compares choice to each letter individually.

Be sure to compile Listing 14.12 along with workermi.cpp.

Listing 14.12. workmi.cpp

// workmi.cpp -- multiple inheritance

// compile with workermi.cpp

#include

#include

#include "workermi.h"

const int SIZE = 5;

int main()

{

   using std::cin;

   using std::cout;

   using std::endl;

   using std::strchr;

   Worker * lolas[SIZE];

    int ct;

    for (ct = 0; ct < SIZE; ct++)

    {

        char choice;

        cout << "Enter the employee category:\n"

            << "w: waiter  s: singer  "

            << "t: singing waiter  q: quit\n";

        cin >> choice;

        while (strchr("wstq", choice) == NULL)

        {

            cout << "Please enter a w, s, t, or q: ";

            cin >> choice;

        }

        if (choice == 'q')

            break;

        switch(choice)

        {

            case 'w':   lolas[ct] = new Waiter;

                        break;

            case 's':   lolas[ct] = new Singer;

                        break;

            case 't':   lolas[ct] = new SingingWaiter;

                        break;

        }

        cin.get();

        lolas[ct]->Set();

    }

    cout << "\nHere is your staff:\n";

    int i;

    for (i = 0; i < ct; i++)

    {

        cout << endl;

        lolas[i]->Show();

    }

    for (i = 0; i < ct; i++)

        delete lolas[i];

    cout << "Bye.\n";

    return 0;

}

Here is a sample run of the program in Listings 14.10, 14.11, and 14.12:

Enter the employee category:

w: waiter  s: singer  t: singing waiter  q: quit

w

Enter waiter's name: Wally Slipshod

Enter worker's ID: 1040

Enter waiter's panache rating: 4

Enter the employee category:

w: waiter  s: singer  t: singing waiter  q: quit

s

Enter singer's name: Sinclair Parma

Enter worker's ID: 1044

Enter number for singer's vocal range:

0: other   1: alto   2: contralto   3: soprano

4: bass   5: baritone   6: tenor

5

Enter the employee category:

w: waiter  s: singer  t: singing waiter  q: quit

t

Enter singing waiter's name: Natasha Gargalova

Enter worker's ID: 1021

Enter waiter's panache rating: 6

Enter number for singer's vocal range:

0: other   1: alto   2: contralto   3: soprano

4: bass   5: baritone   6: tenor

3

Enter the employee category:

w: waiter  s: singer  t: singing waiter  q: quit

q

Here is your staff:

Category: waiter

Name: Wally Slipshod

Employee ID: 1040

Panache rating: 4

Category: singer

Name: Sinclair Parma

Employee ID: 1044

Vocal range: baritone

Category: singing waiter

Name: Natasha Gargalova

Employee ID: 1021

Vocal range: soprano

Panache rating: 6

Bye.

Let’s look at a few more matters concerning MI.

Mixed Virtual and Nonvirtual Bases