#include <time.h>
#include <stdio.h>
static void
print_globals(struct tm *tm)
{
  printf("%04d-%02d: %s/%s (%s) %d %ld (%ld)\n",
	 1900 + tm->tm_year, 1 + tm->tm_mon,
	 tzname[0], tzname[1], tm->tm_zone?tm->tm_zone:"NULL",
	 daylight, timezone, -tm->tm_gmtoff);
}

int main() {
  struct tm tm = {0, 0, 0, 1, 0, -100};
  print_globals(&tm);
  tzset();
  print_globals(&tm);
  mktime(&tm);
  print_globals(&tm);
  tm.tm_year = 43;
  mktime(&tm);
  print_globals(&tm);
  tm.tm_year = 45;
  tm.tm_mon = 8;
  mktime(&tm);
  print_globals(&tm);
}