Start with the COUNTEN2 program in this chapter. It can increment or decrement a counter, but only using prefix notation. Using inheritance, add the ability to use postfix notation for both incrementing and decrementing. (See Chapter 8 for a description of postfix notation.)

SOLUTION:

#include "stdafx.h"

#include "iostream"

using namespace std;

/////////////////////////////////////////////////////////////////////////////////////////

class Counter        

{

            protected:

                        unsigned int count;

            public:

                        Counter( ) : count( )

                                    { }

                        Counter(int c) : count(c)

                                    { }

                        unsigned int get_count( ) const

                        {

return count;

}

                        Counter operator ++ ( )

                        {

return Counter(++count);

}

};

class CountDn : public Counter

{

            public:

                        CountDn( ) : Counter( )

                                    { }

                        CountDn(int c) : Counter(c)

                                    { }

                        CountDn operator -- ( )

                        {

return CountDn(--count);

}

};

class post_inc_dec : public Counter

{

            public:

                        post_inc_dec( ) : Counter( )

                                    { }

                        post_inc_dec(int c) : Counter(c)

                                    { }

                        post_inc_dec operator ++ (int)

                        {

return post_inc_dec(count++);

}

                        post_inc_dec operator -- (int)

                                    { return post_inc_dec(count--); }

};

/////////////////////////////////////////////////////////////////////////////////////////

void main( )

{

            CountDn c1;

            CountDn c2(100);

            post_inc_dec c3(200);

            cout << "c1=" << c1.get_count( );

            cout << "\nc2=" << c2.get_count( );

            cout << "\nc3=" << c3.get_count( );

            ++c1;  

c1++;

++c1;

            cout << "\nc1=" << c1.get_count( );

            --c2;

            --c2;

            cout << "\nc2=" << c2.get_count( );

            c3--;

            c3++;

            c3++;

            c3++;

            post_inc_dec c4 = c3--;

            cout << "\nc3=" << c3.get_count( );

            cout << endl;

            system("pause");

}

OUTPUT:

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