How to output a calendar program with functions to a .txt file

Question

The question I have is figuring out what is wrong with my program and why it will not write to an output file that I have specified.

#include <iostream>
#include <cstdlib>
#include <iomanip>
#include <fstream>
using namespace std;

int numOfDaysInAMonth(int, int);
void printMonth(int);
void printDaysofMonth(int, int&);
void skipToDay(int);
int main()
{
  ofstream ofile;
  ofile.open("calendar.txt");

  int year, firstDayInCurrentMonth;
  int currentMonth = 1;
  int numDays;

  cout << "What year is this? ";
  cin >> year;

  cout << endl;

  cout << " 0 - Sunday\n";
  cout << " 1 - Monday\n";
  cout << " 2 - Tuesday\n";
  cout << " 3 - Wednesday\n";
  cout << " 4 - Thursday\n";
  cout << " 5 - Friday\n";
  cout << " 6 - Saturday\n";

  cout << "What day of then week is Jan 1? ";

  cin >> firstDayInCurrentMonth;

  ofile << year << endl;

  while (currentMonth <= 12) {
    numDays = numOfDaysInAMonth(currentMonth, year);
    printMonth(currentMonth);
    printDaysofMonth(numDays, firstDayInCurrentMonth);
    ofile << endl << endl << endl;
    currentMonth = currentMonth + 1;
  }

  ofile << endl;

  system("pause");
  return 0;
}

I use ofile to output the text but it is not being returned correctly.

// This function returns the number of days in a month
int numOfDaysInAMonth(int m, int y)
{
  if (m == 1)
    return(31);
  else if (m == 2 && y % 4 != 0)
    return(28);
    if (m == 2 && y % 4 == 0)
        return(29);
  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);
}

    // It takes the number of the month and prints outs the name of the month and the frame of the calander
void printMonth(int m)
{
  ofstream ofile;
  ofile.open("calendar.txt");

  if (m == 1)
  {
    ofile << "January" << endl;
  }
  else if (m == 2)
  {
    ofile << "February" << endl;
  }
  else if (m == 3)
  {
    ofile << "March" << endl;
  }
  else if (m == 4)
  {
    ofile << "April" << endl;
  }
  else if (m == 5)
  {
    ofile << "May" << endl;
  }
  else if (m == 6)
  {
    ofile << "June" << endl;
  }
  else if (m == 7)
  {
    ofile << "July" << endl;
  }
  else if (m == 8)
  {
    ofile << "August" << endl;
  }
  else if (m == 9)
  {
    ofile << "September" << endl;
  }
  else if (m == 10)
  {
    ofile << "October" << endl;
  }
  else if (m == 11)
  {
    ofile << "November" << endl;
  }
  else if (m == 12)
  {
    ofile << "December" << endl;
  }


  ofile << " S  M  T  W  T  F  S" << endl;
  ofile << "_____________________" << endl;
}

// Helps with the skipToDay function
void skip(int i)
{
  ofstream ofile;
  ofile.open("calendar.txt");

  while (i > 0)
  {
    ofile << " ";
    i = i - 1;
  }
}

// This function prints out the days in the month after the header for each month
void printDaysofMonth(int numDays, int &weekDay)
{
  ofstream ofile;
  ofile.open("calendar.txt");

  int day = 1;
  skipToDay(weekDay);
  while (day <= numDays)
  {
    ofile << setw(2) << day << " ";
    if (weekDay == 6)
    {
      ofile << endl;
      weekDay = 0;
    }
    else weekDay = weekDay + 1;
    day = day + 1;
  }
}

// Prints spaces in monthly calander
void skipToDay(int d)
{
  return skip(3 * d);
}

Answer 1

void printDaysofMonth(int numDays, int &weekDay)
{
    ofstream ofile;
    ofile.open("calendar.txt");
    ...
}

int main()
{
  ofstream ofile;
  ofile.open("calendar.txt");
  printDaysofMonth(...);
  ofile << "data...";
  ...
}

The file is already open. The first stream will write over what the second stream had written, if any. Change the function to to pass ofstream by reference:

void printDaysofMonth(ofstream &ofile, int numDays, int &weekDay)
{
    ...
}

int main()
{
  ofstream ofile;
  ofile.open("calendar.txt");
  printDaysofMonth(ofile, ...);
  ...
}

There are other improvements you can make by keeping data in an array, to make the program shorter. Less typing means less potential error.

int is_leap_year(int y)
{
    return (y % 4) == 0 && y % 100 != 0 || y % 400 == 0;
}

int numOfDaysInAMonth(int m, int y)
{
    int days = 0;
    if(m >= 1 && m <= 12)
    {
        const int days_in_month[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
        int days = days_in_month[m - 1];
        if(m == 2 && is_leap_year(y))
            days++;
    }
    return days;
}

const char* get_month_name(int m)
{
    const char *month_name[] = { 
        "January", "February", "March", "April", "May", "June", 
        "July", "August", "September", "October", "November", "December" };
    if(m >= 1 && m <= 12)
        return month_name[m - 1];
    return "month name error";
}

void printMonth(ofstream &ofile, int m)
{
    ofile << get_month_name(m) << "\n";
    ofile << " S  M  T  W  T  F  S" << endl;
    ofile << "_____________________" << endl;
}