Making a Calendar

my assignment is to make a calendar program

-program asks for year
-asks for day of january 1st (0 = sunday, 1 = monday, etc)
-asks for a filename so that all output is thrown into a file

i wanna try and make this program so that the main function isn't a large one (my teacher said a function should never be more then a page long?) - so far i have not thought of a way to accomplish this.

so far, ive gottten it to output and all, but the formatting is terrible.. you'll see if you run the program
can someone help me:
1. make the program output the calendar properly
2. devise a way to make the code cleaner.. with use of multiple functions and what not.

here she is:
[code]
#include <iostream.h>
#include <fstream.h>

int main()
{
      
      int year, jan_day;
      char filename[10];

      cout << "Enter the Year: ";
      cin >> year;

      cout << "Enter the day of week that January 1st is on (0 = sunday, 1 = monday, etc): ";
      cin >> jan_day;

      cout << "Enter the name of the file you want created (example: cal2003.txt): ";
      cin >> filename;

      ofstream file (filename); // create output buffer called 'file' to be used in place of cout. directs all content into 'filename' inputed by the user


      int dim = 31; // days in month
      int a = 1;
      int montharray[12]={'jan', 'feb', 'mar', 'apr', 'may', 'jun', 'jul', 'aug', 'sep', 'oct', 'nov', 'dec'}; //array to store months
      montharray[a] = 1;


      file << montharray[1] << endl;
      file << "Sun\tMon\tTue\tWed\tThr\tFri\tSat" << endl;
      for(int b=0; b < jan_day; b++) // b is number of empty tabs
      {
            file << " \t";
      }

      int c = 0; // variable for containing value of j when it is saturday
      int d = 0; // variable for tabs for each new month

      if (jan_day == 0)
      {
            for(int j = 1; j <= dim; j++) // j is each date (ie. 1, 2, 3, 4 ... 28, 29, 30, 31)
            {
                  if ((j%7 == 1) || (j == 8))
                  {
               file << endl;
                  }
            file << j << "\t";
            }
      }

      if (jan_day != 0)
      {
            for(int j = 1; j <= dim; j++)
            {
                  if ((b - 1 + j == 7) && (j != 8)) // endl when j is saturday
                  {
                        c = j; // assign c the saturday value (can't assign j becaues it is constantly incrementing)
                        file << endl;
                  }
             
                  if (c == j - 7 || c == j - 14 || c == j - 21 || c == j - 28) // endl on multiples of 7 from c
                  {
                        file << endl;
                  }

                  file << j << "\t";
            }
      }

      file << endl;
      
      for (a=1; a < 12; a++) // cycling through the montharray
      {
            // d is number of tabs for next month
            if (jan_day == 0)
            {
                  d = 3;
            }
            else if (jan_day == 1)
            {
                  d = 4;
            }
            else if (jan_day == 2)
            {
                  d = 5;
            }
            else if (jan_day == 3)
            {
                  d = 6;
            }
            else if (jan_day == 4)
            {
                  d = 0;
            }
            else if (jan_day == 5)
            {
                  d = 1;
            }
            else
            {
                  d = 2;
            }



            if (montharray[a] == 'jan' || montharray[a] == 'mar' || montharray[a] == 'may' || montharray[a] == 'jul' ||
                  montharray[a] == 'aug' || montharray[a] == 'oct' || montharray[a] == 'dec')
            {
                  dim = 31; // months with 31 days
            }
            else if (montharray[a] == 'apr' || montharray[a] == 'jun' || montharray[a] == 'sep' || montharray[a] == 'nov')
            {
                  dim = 30; // months with 30 days
            }      
            else
            {
                  dim = 28; // february
                  if (((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0))
                  {
                        dim = 29; // compensate for leap year..
                  }
            }

            d = jan_day + 2;
            file << endl;
            file << montharray[a] << endl;
            file << "Sun\tMon\tTue\tWed\tThr\tFri\tSat" << endl;

            for (int e = 0; e <= d; e++)
            {
                  file << "\t";
            }
            for(int j = 1; j <= dim; j++)
            {
                  if(j % 7 == 0)
                  {
               file << endl;
                  }
            file << j << "\t";
            }
            file << endl;
      }
      
    return 0;
}
[/code]

i could use some help =/