输入年月日判断这是一年中的第几天.

#include <stdio.h>
int main()
{      /*输入年月日判断这是一年中的第几天.*/
    int year,month,day,sum,leap;
    printf("please input year month day\n");
    scanf("%d %d %d",&year,&month,&day);
    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;
        defaut:printf("data error.\n");
    }
    if(year%400==0||(year%4==0&&year%100!=0))
        leap=1;
    else
        leap=0;
    if(1==leap&&month>3)
    sum++;
    printf("it is the %dth day\n",sum+day);
    getch();
    return 0;

}