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Calendar Reference

RCUniversal (9)
I found this code online while searching for a solution to something I wanted to do. I am wondering if it is possible to change this code to use it as a reference so that when a user were to input a a day, month, and year it would return what day of the week it is. Is it possible? Is there an easier way to accomplish what I'm talking about? Please help.

[\code]

#include <iostream>
#include <cstdlib>
#include <iomanip>

using namespace std;

bool isLeapYear(int); //good check for leap years
int firstDayofnewyearMonth(int);
int numOfDaysInMonth(int, bool); // takes the number of the month, a flag saying whether year is leap
void printHeader(int); // takes the number of the month, and the first day, prints, and updates
void printMonth(int, int&); // the first day of the next month
void skip(int);// prints the specified amount of spaces
void skipToDay(int);// prints leading spaces in monthly calendar
void disaster(); // terminates program in case of unrecoverable errors

int main()
{
system("color f1 ");
int year, firstDayInCurrentMonth;
int currentMonth = 1;
int numDays;
bool leap;
cout << "What year do you want a calendar for? ";
cin >> year;
cout << endl;
firstDayInCurrentMonth = firstDayofnewyearMonth(year);
leap = isLeapYear(year);
skip(9);
cout << year << endl;
while (currentMonth <= 12)
{
numDays = numOfDaysInMonth(currentMonth, leap);
printHeader(currentMonth);
printMonth(numDays, firstDayInCurrentMonth);
cout << endl << endl << endl;
currentMonth = currentMonth + 1;
}
cout << endl;
system("PAUSE");
}
bool isLeapYear(int year)
{
return ((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0);
}
int firstDayofnewyearMonth(int year)
{
int day_start;
int x1, x2, x3;
x1 = (year - 1) / 4;
x2 = (year - 1) / 100;
x3 = (year - 1) / 400;
day_start = (year + x1 - x2 + x3) % 7;
return day_start;
}
int numOfDaysInMonth(int m, bool leap)
{
if (m == 1) return(31);
else if (m == 2) if (leap) return(29); else return(28);
else if (m == 3) return(31);
else if (m == 4) return(30);
else if (m == 5) return(31);
else if (m == 6) return(30);
else if (m == 7) return(31);
else if (m == 8) return(31);
else if (m == 9) return(30);
else if (m == 10) return(31);
else if (m == 11) return(30);
else if (m == 12) return(31);
else disaster();
}
void printHeader(int m)
{
if (m == 1)
{
skip(7);
cout << "January" << endl;
}
else if (m == 2) { skip(7); cout << "February" << endl; }
else if (m == 3) { skip(7); cout << "March" << endl; }
else if (m == 4) { skip(7); cout << "April" << endl; }
else if (m == 5) { skip(7); cout << "May" << endl; }
else if (m == 6) { skip(7); cout << "June" << endl; }
else if (m == 7) { skip(7); cout << "July" << endl; }
else if (m == 8) { skip(7); cout << "August" << endl; }
else if (m == 9) { skip(7); cout << "September" << endl; }
else if (m == 10) { skip(7); cout << "October" << endl; }
else if (m == 11) { skip(7); cout << "November" << endl; }
else if (m == 12) { skip(7); cout << "December" << endl; }
else disaster();

cout << " S M T W T F S" << endl;
cout << "____________________" << endl;
}
void skip(int i)
{
while (i > 0)
{
cout << " ";
i = i - 1;
}
}
void printMonth(int numDays, int &weekDay)
{
int day = 1;
skipToDay(weekDay);
while (day <= numDays)
{
cout << setw(2) << day << " ";
if (weekDay == 6)
{
cout << endl;
weekDay = 0;
}
else weekDay = weekDay + 1;
day = day + 1;
}
}
void skipToDay(int d)
{
return skip(3 * d);
}
void disaster()
{
cout << "Disaster! Exiting ..." << endl;
exit(-1);
}

[\code]
gunnerfunner (2127)
... user were to input a a day, month, and year it would return what day of the week it is.

using the inbuilt libraries and functions:
http://en.cppreference.com/w/cpp/chrono/c/tm
http://en.cppreference.com/w/cpp/chrono/c/mktime
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#include <iostream>
#include <chrono>
#include <ctime>

void getDay (int year, int mon, int day)//suggest input validation
{
    struct std::tm t;
    t.tm_sec = 0;
    t.tm_min = 1;
    t.tm_hour = 1;
    t.tm_mday = day;       // day of month (1 .. 31)
    t.tm_mon = mon-1;      // month of year (0 .. 11)
    t.tm_year = year-1900; // year since 1900
    t.tm_isdst = -1;       // determine whether daylight saving time
    std::time_t tt = std::mktime(&t);
    if (tt == -1) {
        throw "no valid system time";
    }
    switch(t.tm_wday)
    {
        case 0: std::cout << "Sun \n"; break;
        case 1: std::cout << "Mon \n"; break;
        case 2: std::cout << "Tue \n"; break;
        case 3: std::cout << "Wed \n"; break;
        case 4: std::cout << "Thu \n"; break;
        case 5: std::cout << "Fri \n"; break;
        case 6: std::cout << "Sat \n"; break;
        default: std::cout << " \n"; break;
    }
}

int main()
{
   getDay(2017, 06, 10);
}

RCUniversal (9)
This is not quite what I'm trying to do. I want the user to enter the year, the month, and the day. Then it uses the numbers to figure out what day of the week it is.

P.S. - Your program kept telling me it was Saturday.
RCUniversal (9)
Gunnerfunner,

this is what I have so far. I was wondering why it wont accept any date after 1970. Also is it possible to limit the months to the number of days in that month?

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#include<iostream>
#include<cmath>
#include<string>
#include<ctime>
#include<chrono>

using namespace std;

int main()
{
	int month;
	int day;
	int year;
	int time;
	char confirm;

	cout << "Year(Any Year After and Including 1970):  ";
	cin >> year;
	cout << "Month(1 - 12):  ";
	cin >> month;
	cout << "Day:  ";
	cin >> day;
	cout << "Time(24 Hour Format):  ";
	cin >> time;

	struct std::tm t;
	t.tm_sec = 0;
	t.tm_min = 1;
	t.tm_hour = 1;
	t.tm_mday = day;       // day of month (1 .. 31)
	t.tm_mon = month - 1;      // month of year (0 .. 11)
	t.tm_year = year - 1900; // year since 1900
	t.tm_isdst = -1;       // determine whether daylight saving time
	time_t tt = mktime(&t);
	if (tt == -1)
	{
		throw "No valid system time";
	}

	switch (t.tm_wday)
	{
	case 0:
	{
		cout << "Sun \n";
		if (time >= 0 && time < 500)
		{
			cout << "Sorry we aren't open yet.\n";
		}
		else if (time >= 2300 && time <= 2400)
		{
			cout << "Sorry we are closed for the day.\n";
		}
		else if (time >= 500 && time <= 2300)
		{
			cout << "Congrats!  We are open for now.\n";
			break;
		}
	case 1:
	{
		cout << "Mon \n";
		if (time >= 0 && time < 500)
		{
			cout << "Sorry we aren't open yet.\n";
		}
		else if (time >= 2300 && time <= 2400)
		{
			cout << "Sorry we are closed for the day.\n";
		}
		else if (time >= 500 && time <= 2300)
		{
			cout << "Congrats!  We are open for now.\n";
			break;
		}
	case 2:
	{
		cout << "Tue \n";
		if (time >= 0 && time < 500)
		{
			cout << "Sorry we aren't open yet.\n";
		}
		else if (time >= 2300 && time <= 2400)
		{
			cout << "Sorry we are closed for the day.\n";
		}
		else if (time >= 500 && time <= 2300)
		{
			cout << "Congrats!  We are open for now.\n";
			break;
		}
	case 3:
	{
		cout << "Wed \n";
		if (time >= 0 && time < 500)
		{
			cout << "Sorry we aren't open yet.\n";
		}
		else if (time >= 2300 && time <= 2400)
		{
			cout << "Sorry we are closed for the day.\n";
		}
		else if (time >= 500 && time <= 2300)
		{
			cout << "Congrats!  We are open for now.\n";
			break;
		}
	case 4:
	{
		cout << "Thu \n";
		if (time >= 0 && time < 500)
		{
			cout << "Sorry we aren't open yet.\n";
		}
		else if (time >= 2300 && time <= 2400)
		{
			cout << "Sorry we are closed for the day.\n";
		}
		else if (time >= 500 && time <= 2300)
		{
			cout << "Congrats!  We are open for now.\n";
			break;
		}
	case 5:
	{
		cout << "Fri \n";
		if (time >= 0 && time < 500)
		{
			cout << "Sorry we aren't open yet.\n";
		}
		else if (time >= 2300 && time <= 2400)
		{
			cout << "Sorry we are closed for the day.\n";
		}
		else if (time >= 500 && time <= 2300)
		{
			cout << "Congrats!  We are open for now.\n";
			break;
		}
	}
	case 6:
	{
		cout << "Sat \n";
		if (time >= 0 && time < 500)
		{
			cout << "Sorry we aren't open yet.\n";
		}
		else if (time >= 2300 && time <= 2400)
		{
			cout << "Sorry we are closed for the day.\n";
		}
		else if (time >= 500 && time <= 2300)
		{
			cout << "Congrats!  We are open for now.\n";
			break;
		}
	default:
		cout << "Coming Soon";
		break;
	}

	cout << "Welcome to the Roadkill Cafe." << endl;
	}
	}
	}
	}
	}
	}
	system("PAUSE");
	return 0;
}


RCUniversal
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