第十六周-计算该日在本年中是第几天

#include <stdio.h>
#include <stdlib.h>
typedef struct
{
    int year;
    int month;
    int day;
} y_m_d;
int main()
{
    y_m_d date;
    int days(y_m_d);
    //y_m_d是自定义的类型
    int day_sum;
    scanf("%d%d%d",&date.year,&date.month,&date.day);
    day_sum=days(date);
    printf("%d\n",day_sum);
    return 0;
}
int days(y_m_d date)
{
    int i,count=date.day;
    for(i=1; i<date.month; ++i)
    {
        switch(i)
        {
        case 2:
            count+=((date.year%4==0&&date.year%100!=0)||date.year%400==0)?29:28;
            break;
        case 4:
        case 6:
        case 9:
        case 11:
            count+=30;
            break;
        default:
            count+=31;
            break;
        }
    }
    return count;
}