在C中的时区之间转换

Question

我需要在C语言中转换时区之间的时间(在linux上,所以任何特定的东西都会这样做).

我知道我当前的时间,本地和UTC,我有目标时间的偏移量.我试图使用mktime,gmtime,localtime和类似的功能集,但仍然无法弄明白.

提前致谢.

Answer 1

由于评论不允许发布代码,因此单独发布答案.如果您知道"本地"时间和"UTC"时间,则可以计算"其他"时间与"本地"时间的偏移量.然后将struct tm转换为日历时间,添加所需的秒数(作为目标时间的偏移量),并将其转换回struct tm:

(编辑以说明使用mktime标准化的另一个场景)

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>

int main(int argc, char *argv) {
  struct timeval tv_utc;
  struct tm *local_tm, *other_tm;

  /* 'synthetic' time_t to convert to struct tm for the other time */
  time_t other_t_synt;
  /* Other time is 1 hour ahead of local time */
  int other_local_delta = 1*3600; 


  /* the below two lines are just to set local_tm to something */
  gettimeofday(&tv_utc, NULL);
  local_tm = localtime(&tv_utc.tv_sec);

  printf("Local time: %s", asctime(local_tm));

  #ifdef DO_NOT_WRITE_TO_LOCAL_TM
  other_t_synt = mktime(local_tm) + other_local_delta;
  #else
  local_tm->tm_sec += other_local_delta;
  /* mktime will normalize the seconds to a correct calendar date */
  other_t_synt = mktime(local_tm);
  #endif

  other_tm = localtime(&other_t_synt);

  printf("Other time: %s", asctime(other_tm));

  exit(0);
}