请问这个代码的问题
#include <stdio.h>
int main()
{
/* 定义需要计算的日期 */
int year = 2008;
int month = 8;
int day = 8;
int sum,flag;
switch(month)
{
case:1;sum= 0;break;
case:2;sum= 31;break;
case:3;sum=59; break;
case:4;sum= 90;break;
case:5;sum=120; break;
case:6;sum=151; break;
case:7;sum= 181;break;
case:8;sum= 212;break;
case:9;sum= 243;break;
case:10;sum=273; break;
case:11;sum= 304;break;
case:12;sum=334; break;
default:printf("一年只有12个月份哦~");break;
}
sum= sum+day;
if((year%4==0 && year%100!=0) || year%400==0)
flag=1;
else
flag=0;
if(flag==1&&month>2)
sum = sum++;
printf("%d年%d月%d日是该年的第%d天。",year,month,day,sum);
return 0;
}