pr11013.cpp

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////////////////////////////////////////
// File Name: pr11013.cpp
////////////////////////////////////////
#include <iostream>

// A forward reference to tell the compiler
// that the Date class is defined later.
class Date;

////////////////////////////////////////
// CustomDate date class.
////////////////////////////////////////
class CustomDate
{
    int da, yr;

public:
    CustomDate(int d = 0, int y = 0)
        { da = d; yr = y;}
    void display() const
        {std::cout << std::endl << yr << '-' << da;}

    // Allow Date member functions to
    // see CustomDate private members.
    friend Date;
};

////////////////////////////////////////
// Date date class.
////////////////////////////////////////
class Date
{
    int mo, da, yr;

public:
    Date(int m, int d, int y) { mo = m; da = d; yr = y; }
    operator CustomDate();
};

// Member conversion function (CustomDate <- Date).
Date::operator CustomDate()
{
    static int dys[] = {31,28,31,30,31,30,31,31,30,31,30,31};
    CustomDate cd(0, yr);
    for (int i = 0; i < mo-1; i++)
        cd.da += dys[i];
    cd.da += da;
    return cd;
}

////////////////////////////////////////
// The main() function.
////////////////////////////////////////
int main()
{
    Date dt(11,17,89);
    CustomDate cd(dt);
    cd.display();

    return 0;
}