time时间相关的一些函数

#include <utmp.h>

#include <utmpx.h>

#include <stdio.h>

#include <time.h>

int main()

{

time_t t1;

struct timeval t2;

struct tm *local_time, *utc_time;

char date_str[50];

t1 = time(NULL);

printf("Seconds since Epoch %d, %d/n", t1, sizeof(t1));

printf("Date is: %s/n", ctime(&t1));

gettimeofday(&t2, NULL);

printf("Seconds since Epoch %d,%d/n", t2.tv_sec, t2.tv_usec );

utc_time = gmtime(&t2.tv_sec);

local_time = localtime(&t2.tv_sec);

printf("UTC date: %s/n", asctime(utc_time));

printf("Local date: %s/n", asctime(local_time));

strftime(date_str, sizeof(date_str), "%A %B %C %Y, %r", local_time);

printf("Format date: %s/n", date_str);

return 0;

}

gmtime和localtime的区别在于，gmtime是基于UTC的，而localtime是基于TZ环境变量的。