Doc.

3 ADT&Classes.pdf

Code

date.h

class date {
private:
    int day; // day number: 1-31
    int month; // month number: 1-12
    int year; // year number: 1901-2099
public:
    void set(int d,int m,int y); // set date
    bool valid(); // true if date is valid
    void print(); // display "Month dd, yyyy"
    int year_day(); // day number in current year
    int days_1901(); // days since Jan 1,1901
    int weekday(); // return weekday number
};

date.cpp

// Implantation of Date Class
#include <iostream.h>
#include "date.h"

void date::set(int d, int m, int y) {
    day = d; month = m; year = y;
}

bool date::valid() {
    int month_days[] = {0,31,28,31,30,31,30,31,31,30,31,30,31};
    if (year < 1901 || year > 2099) return false;
    if (month < 1 || month > 12) return false;
    if (year % 4 == 0) month_days[2] = 29;
    if (day < 1 || day > month_days[month]) return false;
    return true;
}

void date::print() {
    char *name[] = {"", "Jan","Feb","Mar","Apr","May","Jun",
                    "Jul","Aug","Sep","Oct","Nov","Dec"};
    if (!valid()) cout << "Invalid Date\\n";
    else cout << name[month] << ' ' << day << ", " << year << endl;
}

int date::year_day() {
    if (!valid()) return -1;
    int sum_days[] = {0,31,59,90,120,151,181,212,243,273,304,334};
    int yr_day = sum_days[month-1]+day;
    if (year % 4 == 0 && month > 2) yr_day++;
    return yr_day;
}

int date::days_1901() {
    if (!valid()) return -1;
    return (int) ((year-1901)*365.25 + year_day() – 1);
}

int date::weekday() {
// Sunday = 0, Monday = 1, January 1, 1901 is Tuesday = 2
    if (!valid()) return -1;
    return (days_1901() + 2) % 7;
}

main.cpp

#include <iostream.h>
#include "date.h"

void main() {
    date oneDay;
    int d,m,y;

    cout << "Enter a day, month, year: "; cin >> d >> m >> y;
    oneDay.set(d, m, y);

    cout << oneDay.year_day() << endl;
    cout << oneDay.days_1901() << endl;
    cout << oneDay.weekday() << endl;
    
    oneDay.print();
    oneDay.year = 2000;
}