C Program to Implement Calender Program to display Day of the month

C Program to Implement Calender Program to display Day of the month

 #include<stdio.h>
#include<conio.h>
#include<math.h>

int fm(int date, int month, int year)
 {
   int fmonth, leap;

   //leap function 1 for leap & 0 for non-leap
   if ((year % 100 == 0) && (year % 400 != 0))
      leap = 0;
   else if (year % 4 == 0)
      leap = 1;
   else
      leap = 0;

   fmonth = 3 + (2 - leap) * ((month + 2) / (2 * month))
         + (5 * month + month / 9) / 2;

   //bring it in range of 0 to 6
   fmonth = fmonth % 7;

   return fmonth;
}


int day_of_week(int date, int month, int year)
{

   int dayOfWeek;
   int YY = year % 100;
   int century = year / 100;

   printf("\nDate: %d/%d/%d \n", date, month, year);

   dayOfWeek = 1.25 * YY + fm(date, month, year) + date - 2 * (century % 4);

   //remainder on division by 7
   dayOfWeek = dayOfWeek % 7;

   switch (dayOfWeek) {
      case 0:
         printf("weekday = Saturday");
         break;
      case 1:
         printf("weekday = Sunday");
         break;
      case 2:
         printf("weekday = Monday");
         break;
      case 3:
         printf("weekday = Tuesday");
         break;
      case 4:
         printf("weekday = Wednesday");
         break;
      case 5:
         printf("weekday = Thursday");
         break;
      case 6:
         printf("weekday = Friday");
         break;
      default:
         printf("Incorrect data");
   }
   return 0;
}

int main()
{
   int date, month, year;

   printf("\nEnter the year ");
   scanf("%d", &year);

   printf("\nEnter the month ");
   scanf("%d", &month);

   printf("\nEnter the date ");
   scanf("%d", &date);

   day_of_week(date, month, year);

   return 0;
}