为c mktime在Windows和GNU / Linux有什么不同？ [英] is c mktime different on Windows and GNU/Linux?
问题描述
以下code：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <sys/time.h>
static const char * wday_abb_names[] =
{
"Mon",
"Tue",
"Wed",
"Thu",
"Fri",
"Sat",
"Sun",
};
static void mb_setenv(const char *name, const char *value)
{
#if !(defined _WIN32) || defined HAVE_SETENV
setenv(name, value, 1);
#else
int len = strlen(name)+1+strlen(value)+1;
char *str = malloc(len);
sprintf(str, "%s=%s", name, value);
putenv(str);
#endif
}
static void mb_unsetenv(const char *name)
{
#if !(defined _WIN32) || defined HAVE_SETENV
unsetenv(name);
#else
int len = strlen(name)+2;
char *str = malloc(len);
sprintf(str, "%s=", name);
putenv(str);
free(str);
#endif
}
time_t mb_timegm(struct tm *tm)
{
time_t ret;
char *tz;
tz = getenv("TZ");
mb_setenv("TZ", "");
tzset();
ret = mktime(tm);
if (tz)
{
mb_setenv("TZ", tz);
}
else
{
mb_unsetenv("TZ");
}
tzset();
return ret;
}
time_t get_test_time()
{
struct tm msg_time;
msg_time.tm_isdst = 0;
msg_time.tm_wday = 4;
msg_time.tm_mon = 5;
msg_time.tm_mday = 16;
msg_time.tm_hour = 4;
msg_time.tm_min = 53;
msg_time.tm_sec = 0;
msg_time.tm_year = 111; //2011 - 1900
time_t retval = mb_timegm(&msg_time);
printf("final msg_time = %ld\n", retval);
return retval;
}
void print_time(const char *msg, struct tm *t)
{
printf("%s %s, %02d.%02d.%2d %2d:%02d\n", msg,
wday_abb_names[t->tm_wday], t->tm_mday, t->tm_mon, t->tm_year,
t->tm_hour, t->tm_min);
}
int main()
{
printf( "=== ENVIRON ===\n");
printf("TZ = %s\n", getenv("TZ"));
time_t now;
struct tm l, g;
time(&now);
l = *localtime(&now);
g = *gmtime(&now);
print_time("Local time :", &l);
print_time("utc :", &g);
printf("=== END ENVIRON ===\n\n");
time_t tt = get_test_time();
printf("fix test (16.6.2011 04:53) --> %s\n", ctime(&tt));
printf("done.\n");
return 0;
}
在GNU / Linux上运行它产生：
running on GNU/Linux it produces:
=== ENVIRON ===
TZ = (null)
Local time : Sat, 24.05.111 14:20
utc : Sat, 24.05.111 12:20
=== END ENVIRON ===
final msg_time = 1308199980
fix test (16.6.2011 04:53) --> Thu Jun 16 06:53:00 2011
done.
Win7上运行它产生：
running on Win7 it produces:
=== ENVIRON ===
TZ = (null)
Local time : Sat, 24.05.111 14:25
utc : Sat, 24.05.111 12:25
=== END ENVIRON ===
final msg_time = 1308196380
fix test (16.6.2011 04:53) --> Thu Jun 16 05:53:00 2011
done.
这两个系统有一个时区UTC + 1，包括DST（使UTC + 2的效应），这两个系统都没有任何时间的问题，在所有的 - 除了显示的差异
Both Systems have a Timezone of UTC+1 including DST (that makes UTC+2 in effect) and both systems are not having any time-problems at all - except for the difference displayed.
正如你所看到的，最后msg_time缺失正是3600秒;所以它不是一个的ctime问题。
As you can see, the "final msg_time" is missing exactly 3600 seconds, so it is not a problem in ctime.
任何人都可以向我解释为什么mktime似乎表现在GNU / Linux和Windows不同 - ？或如何纠正
Can anybody explain to me why mktime seems to behave different on GNU/Linux and Windows - or how to correct that?
编辑：结果
这两种系统（呼叫后 tzset（））的报告TZNAME [0] = CET，TZNAME [1] = CEST，白天= 1时区= -3600
Both systems (after calling tzset()) are reporting tzname[0] = CET, tzname[1] = CEST, daylight=1, timezone = -3600
推荐答案
我mb_timegm是基于对男子3 timegm规定的code 和它说设置TZ环境变量UTC来做到这一点 SETENV（TZ，）; 被称为
My mb_timegm was based on the code stated in man 3 timegm and it stated
"set the TZ environment variable to UTC" to do this setenv("TZ", ""); is called.
不过 - 这并不工作在Windows上
However - this does not work on windows.
使用 SETENV（TZ，UTC）; （或者，在上述情况下，mb_setenv），而不是解决问题。
Using setenv("TZ", "UTC"); (or, in the above case mb_setenv) instead fixes the problem.
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