linux下用time(NULL)函数和localtime()获取当前时间的方法

/* time - 获取计算机系统当前的日历时间(Calender Time)
 *     处理日期时间的函数都是以本函数的返回值为基础进行运算
 *
 * 函数原型：
 *   #include <time.h>
 * 
 *   time_t time(time_t *calptr);
 *
 * 返回值：
 *   成功：秒数，从1970-1-1,00:00:00
 *
 * 使用：
 *   time_t now;
 * 
 *   time(&now); // == now = time(NULL);
 */

/*
 * localtime - 将时间数值变换成本地时间,考虑到本地时区和夏令时标志
 *
 * 函数声明:
 *   #include <time.h>
 *
 *   struct tm * localtime(const time_t *timer);
 *
 */

//结构tm的定义为： 
 struct tm 
 { 
   int tm_sec; /* Seconds: 0-59 (K&R says 0-61?) */ 
   int tm_min; /* Minutes: 0-59 */ 
   int tm_hour; /* Hours since midnight: 0-23 */ 
   int tm_mday; /* Day of the month: 1-31 */ 
   int tm_mon; /* Months *since* january: 0-11 */ 
   int tm_year; /* Years since 1900 */ 
   int tm_wday; /* Days since Sunday (0-6) */ 
   int tm_yday; /* Days since Jan. 1: 0-365 */ 
   int tm_isdst; /* +1 Daylight Savings Time, 0 No DST, 
    * -1 don't know */ 
 }; 

/*
* time();
* @author 李政 <1244109467@qq.com>
*/

#include <time.h> 
#include <stdio.h> 

int main(int argc, char* argv[])
{ 
  struct tm *tp; 
  time_t t = time(NULL); 
  tp = localtime(&t);

  printf("%d/%d/%d\n",tp->tm_mon+1,tp->tm_mday,tp->tm_year+1900); 
  printf("%d:%d:%d\n",tp->tm_hour,tp->tm_min,tp->tm_sec); 

  return 0;
}