요일 프로그램

동생 숙제를 하다가,,,,,,

#include <stdio.h>
#include <stdlib.h>

void main() // int main(int arcg, char **argv)
{

 int year = 0, month = 0, day = 0;
    int total = 0, day_count = 0;

 int i;

 printf("Enter the Year: ");
 scanf("%d", &year);
 printf("Enter the Month: ");
 scanf("%d", &month);
 printf("Enter the Day: ");
    scanf("%d", &day);

 for(i = 1; i < month; i++)
 { 

if(i == 2)
{

if((year%4 == 0 && year%100 != 0) || year%400 == 0) day_count = 29; 
   
else day_count = 28;

}

else if(i==4 || i==6 || i==9 || i==11) day_count = 30; 
  
else day_count = 31; 
 

total += day_count; 

 }

 total = ( (year-1) * 365 + (year-1) / 4 - (year-1) / 100 + (year-1) / 400 + total + day) % 7;

 switch(total)
 {

      case 0: printf("%d Years %d Months %d Days is Sunday\n", year, month, day); break;
      case 1: printf("%d Years %d Months %d Days is Monday\n", year, month, day); break;
      case 2: printf("%d Years %d Months %d Days is Tuesday\n", year, month, day); break;
      case 3: printf("%d Years %d Months %d Days is Wednesday\n", year, month, day); break;
      case 4: printf("%d Years %d Months %d Days is Thursday\n", year, month, day); break;
      case 5: printf("%d Years %d Months %d Days is Friday\n", year, month, day); break;
      case 6: printf("%d Years %d Months %d Days is Saturday\n", year, month, day); break;

}

}