C 语言程序设计实践 4.6 第几天

AC代码：

#include <stdio.h>  int main()  {      int y,m,d,s=0;      scanf("%d/%d/%d",&y,&m,&d);      switch (m)      {          case 12:s+=30;          case 11:s+=31;                  case 10:s+=30;          case 9:s+=31;           case 8:s+=31;          case 7:s+=30;          case 6:s+=31;                  case 5:s+=30;          case 4:s+=31;           case 3:if ((y%4 == 0 && y%100!=0) || (y%400==0)){              s+=29;              }else{                  s+=28;                  }          case 2:s+=31;          case 1:s+=d;          }                    printf("%d\n",s);                    return 0;  }