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#include "std_lib_facilities_3.h"
bool LeapYear (int year)
// "year" must be between 1900 and 2999.
// Returns true if "year" is a leap year.
{
// true, if year is divisible by 4, and ...
// ... either not divisible by 100, or divisible by 400.
return (year % 4 == 0 &&
(year % 100 != 0  year % 400 == 0));
}
//**************************************
const int daysInMonth[12] = {
31, 28, 31, 30, 31, 30,
31, 31, 30, 31, 30, 31
};
// Days from the beginning of the year
// to the beginning of the month:
const int daysToMonth[12] = {
0, 31, 59, 90, 120, 151,
181, 212, 243, 273, 304, 334
};
const char *dayName[7] = {
"Sunday",
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday",
"Saturday" // ** made constant " #"
};
const int DAY0 = 1; // Day of week for 01011900 is Monday = 1.
//**************************************
bool ValidDate (int month, int day, int year)
// Returns true if monthdayyear is a valid date between
// 01011900 and 12312999.
{
bool valid = false; // First assume the date is invalid.
int days;
// If year and month have valid values:
if (year >= 1900 && year <= 2999 &&
month >= 1 && month <= 12) {
// Get the number of days in this month from the table:
days = daysInMonth[month1]; // (1, because the indices
// of an array start from 0.)
// If February of a leap year  increment the number
// of days in this month:
if (month == 2 && LeapYear(year))
days++;
// Check that the given day is within the range.
// If so, set valid to true:
if (day >= 1 && day <= days)
valid = true;
}
return valid;
}
//**************************************
long DaysSince1900 (int month, int day, int year)
// Returns the number of days elapsed since 01011900
// to monthdayyear
{
long days;
// Calculate days to 0101 of this year with correction for
// all the previous leap years:
if (year == 1900)
days = 0;
else
days = long(year  1900) * 365
+ (year  1901) / 4 // +1 for each 4th year
 (year  1901) / 100 // 1 for each 100th year
+ (year  1601) / 400; // +1 for each 400th year,
// starting at 2000
// Add days for previous months with correction for
// the current leap year:
days += daysToMonth[month1];
if (LeapYear(year) && month > 2) days++;
// Add days since the beginning of the month:
days += day  1;
return days;
}
//**************************************
int DayOfWeek (int month, int day, int year)
// Returns the day of the week for a given date:
// 0  Sunday, 1  Monday, etc.
{
return int((DAY0 + DaysSince1900(month, day, year)) % 7);
}
int main()
{
int month, day = 1, year, days, j;
int weekday;
cout << "Please enter a month and a year==> ";
cin >> month >> year;
if (!ValidDate(month, day, year)) {
cout << "*** Invalid date ***\n";
return 1;
}
if(month == 1) days = 31;
if(month == 2) days = 28;
if(month == 3) days = 31;
if(month == 4) days = 30;
if(month == 5) days = 31;
if(month == 6) days = 30;
if(month == 7) days = 31;
if(month == 8) days = 31;
if(month == 9) days = 30;
if(month == 10) days = 31;
if(month == 11) days = 30;
if(month == 12) days = 31;
for(j = 1; j <= days; j++)
{
cout << j << " ";
weekday = DayOfWeek(month, j, year);
if(weekday == 0) cout << "Sunday 0 ";
if(weekday == 1) cout << "Monday 1 ";
if(weekday == 2) cout << "Tuesday 2 ";
if(weekday == 3) cout << "Wednesday 3 ";
if(weekday == 4) cout << "Thursday 4 ";
if(weekday == 5) cout << "Friday 5 ";
if(weekday == 6) cout << "Saturday 6";
cout << endl;
}
keep_window_open("~"); // For some Windows(tm) setups
return 0;
}
 