Calender Program in C Programming Language Display Day of the month

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#include<stdio.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; ///f(m) formula fmonth = fmonth %7; ///bring it in range of 0 to 6 return fmonth; } int day_of_week(int date, int month, int year) { int dow; //day of week int YY = year % 100; int century = year / 100; printf("\nDate: %d/%d/%d\n\n",date,month,year); dow = 1.25 * YY + fm(date,month,year) + date - 2*( century % 4); ///function of weekday for Gregorian dow = dow % 7; ///remainder on division by 7 switch (dow) { 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("Enter the day "); scanf("%d",&date); printf("Enter the month "); scanf("%d",&month); printf("Enter the year "); scanf("%d",&year); if(date<=0||date>31||month<=0||month>12) { printf("\nINVALID INPUT\n.......TRY AGAIN.....\n\n"); return main(); } else day_of_week(date,month,year); getch(); }