C語言格式化輸出時間

其實函數就那麼幾個，具體方法也不少，以下列出幾種：

	char timestr[128]="";
	time_t app_time_stamp = 0;
	

	//方法1
	app_time_stamp = time( 0 );
    strftime(timestr, 128, "%a, %d %b %Y %H:%M:%S GMT", localtime(&app_time_stamp));
    printf("Date&Time:%s", timestr);

   //方法2
    struct tm *p;
    p=gmtime(&app_time_stamp); //無時區信息
    strftime(timestr, 128, "%Y-%m-%d %H:%M:%S", p);
    printf("Date&Time:%s", timestr);
  
   //方法3
   struct tm timeinfo;
   time_t t = time( 0 );
   timeinfo = *localtime(&app_time_stamp);
   printf("Date&Time:%s", timestr);

   //方法4
   struct timeval tv_now;
   gettimeofday(&tv_now, NULL);
   localtime_r(&tv_now.tv_sec, &timeinfo);
   printf(""Date&Time:%04d-%02d-%02d,%02d:%02d:%02d",\
            1900+(timeinfo.tm_year), (timeinfo.tm_mon)+1,timeinfo.tm_mday, timeinfo.tm_hour, timeinfo.tm_min, \
            timeinfo.tm_sec);