C程序习题-编写计算天数的函数days[11.2]

    写一个函数days,实现上面的计算。由主函数将年，月，日传递给days函数，计算后将日子数传回主函数输出。

    这道题，其实也主要就是让我们去练习如何去使用结构体代码如下：

#include <stdio.h>
#define ISLOOP(year) (((year) % 4 == 0 && (year) % 100 != 0) || ((year) %400 == 0)) ? 1 : 0
struct date
{
       int year;
       int month;
       int day;
};
const int months[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
int days(struct date *);
int main(int argc, char * argv[])
{
    struct date dt1,*p;
    p = &dt1;
    printf("please input year,month,day:");
    scanf("%d,%d,%d",&dt1.year,&dt1.month,&dt1.day);
    while (dt1.year < 1900 || dt1.month > 12 || dt1.month < 1 || dt1.day > 31 || dt1.day < 1)
    {
          printf("your put data is error,please reinput:\n");
          scanf("%d,%d,%d",&dt1.year,&dt1.month,&dt1.day);
    }
    printf("%d year %d month %d day is : %d day's.",p->year,p->month,p->day,days(p));
    system("pause");
    return 0;
}

int days(struct date *p)
{
    int *month = months;
    int i,result = 0;
    for (i = 0; i < p->month - 1;i++)
    {
        result +=*month++;
    }
    result += p->day;
    if(p->month > 2 && ISLOOP(p->year))
    {
        result += 1;
    }
    return result;
}