两个日期之间的天数有所不同？

Question

比较两天时，我得到的日子不正确。 在这里，我得到699天而不是730天，而dd=14,mm=8,yy=2014

time_t t1, t2;
struct tm my_target_date;

 my_target_date.tm_sec = 0;
 my_target_date.tm_min = 0;
 my_target_date.tm_hour = 0;
 my_target_date.tm_mday = 14;
 my_target_date.tm_mon = 8;
 my_target_date.tm_year = 112; /* Date today */
 t1 = mktime (&my_target_date);
 t2 = time (NULL);
 sprintf (sbuff2,"Number of days since target date : %ld\n", (t2 - t1) / 86400);

Answer 1

在struct tm ，

int tm_mday; // day of the month — [1, 31]
int tm_mon; // months since January — [0, 11]

tm_mday从1开始，但tm_mon从0开始。 因此， my_target_date.tm_mon = 8; 实际上是九月，您要休假一个月。

Answer 2

struct tm结构是-

struct tm {
           int tm_sec;         /* seconds */
           int tm_min;         /* minutes */
           int tm_hour;        /* hours */
           int tm_mday;        /* day of the month */
           int tm_mon;         /* month */
           int tm_year;        /* year */
           int tm_wday;        /* day of the week */
           int tm_yday;        /* day in the year */
           int tm_isdst;       /* daylight saving time */
       };

tm结构的成员是：

   tm_sec    The  number of seconds after the minute, normally in the range 0 to 59, but can be up
             to 60 to allow for leap seconds.

   tm_min    The number of minutes after the hour, in the range 0 to 59.

   tm_hour   The number of hours past midnight, in the range 0 to 23.

   tm_mday   The day of the month, in the range 1 to 31.

   tm_mon    The number of months since January, in the range 0 to 11.

   tm_year   The number of years since 1900.

   tm_wday   The number of days since Sunday, in the range 0 to 6.

   tm_yday   The number of days since January 1, in the range 0 to 365.

   tm_isdst  A flag that indicates  whether  daylight  saving  time  is  in  effect  at  the  time
             described.  The value is positive if daylight saving time is in effect, zero if it is
             not, and negative if the information is not available.

如果将输入设为dd=14,mm=8,yy=2014 ，则表示输入dd=14,mm=8,yy=2014 9月14日，因为在tm_mon month中从0开始。 因此它将计算从September 14th 2014的天数。 因此您在这31天之间不见了。

输入为dd=14,mm=7,yy=2014 。