实现主函数将年、月、日（结构体类型）传递给days函数，days函数计算该年该月该日是该年的第几天并传回主函数输

#include <stdio.h>   struct dt {                      int year;     int month;     int day; }                   date;   int days(struct dt date) {                      int sum;       switch (date.month)     {                      case 1:         sum = date.day;         break;     case 2:         sum = date.day + 31;         break;     case 3:         sum = date.day + 59;         break;     case 4:         sum = date.day + 90;         break;     case 5:         sum = date.day + 120;         break;     case 6:         sum = date.day + 151;         break;     case 7:         sum = date.day + 181;         break;     case 8:         sum = date.day + 212;         break;     case 9:         sum = date.day + 243;         break;     case 10:         sum = date.day + 273;         break;     case 11:         sum = date.day + 304;         break;     case 12:         sum = date.day + 334;         break;     }     if ((date.year % 4 == 0 && date.year % 100 != 0             || date.year % 400 == 0) && date.month >= 3)     {                          sum += 1;     }       return sum; }                  ;   int main(void) {                      printf("请输入日期（年，月，日）\n");     scanf("%d,%d,%d", &date.year, &date.month, &date.day);       printf("\n%d月%d日是%d年的第%d天。", date.month, date.day, date.year, days(date));       return 0; }