c - time.h 是否允许闰年 C

Question

我正在寻找一种方法来找出两个日期之间的差异。该解决方案需要考虑闰年。请参阅下面的两个代码块。 2012 年是闰年而 2013 年不是，所以我不明白为什么两个程序都输出“32 天差异”。如果 time.h 确实考虑到了闰年，它们肯定应该不同吗？

第一个:

#include <stdio.h>  
#include <time.h>       
int main ()
{
  struct tm start_date;
  struct tm end_date;
  time_t start_time, end_time;
  double days;

  start_date.tm_hour = 0;  start_date.tm_min = 0;  start_date.tm_sec = 0;
  start_date.tm_mon = 2; start_date.tm_mday = 1; start_date.tm_year = 112;

  end_date.tm_hour = 0;  end_date.tm_min = 0;  end_date.tm_sec = 0;
  end_date.tm_mon = 3; end_date.tm_mday = 1; end_date.tm_year = 112;

  start_time = mktime(&start_date);
  end_time = mktime(&end_date);

  days = difftime(end_time, start_time) / 86400;

  printf ("%.f days difference\n", days);

  return 0;
}

第二个:

#include <stdio.h>  
#include <time.h>       
int main ()
{
  struct tm start_date;
  struct tm end_date;
  time_t start_time, end_time;
  double days;

  start_date.tm_hour = 0;  start_date.tm_min = 0;  start_date.tm_sec = 0;
  start_date.tm_mon = 2; start_date.tm_mday = 1; start_date.tm_year = 113;

  end_date.tm_hour = 0;  end_date.tm_min = 0;  end_date.tm_sec = 0;
  end_date.tm_mon = 3; end_date.tm_mday = 1; end_date.tm_year = 113;

  start_time = mktime(&start_date);
  end_time = mktime(&end_date);

  days = difftime(end_time, start_time) / 86400;

  printf ("%.f days difference\n", days);

  return 0;
}

Answer 1

Buddy 只需尝试以下操作(将您的月份分别更改为 1 和 2，而不是 2 和 3，它会给您正确的结果，此更改已经过测试)。

根据 Joachim 和 Floris 的说法，tm_mon 成员的月份为零，您计算的是 3 月 1 日和 4 月 1 日之间的差异，而不是 2 月 1 日和 3 月 1 日之间的差异。

  start_date.tm_hour = 0;  start_date.tm_min = 0;  start_date.tm_sec = 0;
  start_date.tm_mon = 1; start_date.tm_mday = 1; start_date.tm_year = 112;

  end_date.tm_hour = 0;  end_date.tm_min = 0;  end_date.tm_sec = 0;
  end_date.tm_mon = 2; end_date.tm_mday = 1; end_date.tm_year = 112;