A Simple Calendar

[krisskady]

Alright, hey everyone!
This is my first time to try this website out, so sorry if I do something incorrectly!

So, I'm attempting to create a calander using basic C++ concepts.
Honestly, I've only been doing this for about 5 weeks now, and alot of the basics of C++ are still giving me trouble.
Anyway, I'm shooting for creating a calander that takes the user input of the year and what day of the week that specific year starts on then outputs a single year calendar. I know it needs take into account leap years.

This is as far as I've gotten, and I'm just kind of confused as to which step I should take next.

I know I need to somehow take out the month input, because I put that in before I refined my requirements, but I'm not sure how to without losing my leap year equations!

Thank you for your help!

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    int month, year;
    int first_day, n_days;
    
    
	cout << "Enter the year:";
      cin >> year;
	cout << endl;

	cout << "Enter the month:";
		cin >> month;
		cout << endl;
    
      cout << "Enter the first day of the year (1 for Sunday, 2 for Monday, etc.): ";
      cin >> first_day;

    
    switch (month)
    {
       case 2:  

if((year%400==0) || (year%4==0 && year%100 !=0))

	n_days = 29;

else
		n_days = 28;
    
break;
       case 4:
       case 6:
       case 9:
       case 11:
		   n_days = 30;
		   break;
	  case 1:
      case 3:
      case 5:
      case 7:
      case 8:
      case 10:
      case 12:
            n_days = 31;
            break; 
	}
            

    
    cout << endl << "Sun\tMon\tTue\tWed\tThr\tFri\tSat\n";
    for (int i = 1; i < first_day; i++)
    {
        cout << " \t";
    }
    for (int j = 1; j <= n_days; j++)
    {
        if (((j + first_day - 2) % 7 == 0) && (j != 1))
            cout << endl;
        cout << j  << "\t";
    }
    cout << endl << endl;

    return 0;
}

[bbrown]

using the zeller algorithm it would look exactly like this (I created and tested this myself):

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

using namespace std;

int main(int argc, char** argv) {
    
    int day = 1, month = 1, year, k, c, d;
    string daysOfTheWeekStrings[] = {
        "Sunday",
        "Monday",
        "Tuesday",
        "Wednesday",
        "Thursday",
        "Friday",
        "Saturday"
    };
    cout << "Please enter a year: ";
    cin >> year;
    
    if (month == 1 || month == 2) {
        month += 10;
        year--;
    } else {
        month -= 2;
    }
    
    month *= 26;
    month -= 2;
    month /= 10;
    
    k = year % 100;
    c = year / 100;
    d = (k + k / 4 + c / 4 + c * 5 + day + month) % 7;
    
    cout << endl << daysOfTheWeekStrings[d];
    
    return 0;
}