int getDay(int *diffday/*天數*/)
{
	time_t rawtime;
	struct tm nowdate, setdate;
	long dftime;
	long daysecond = 60*60*24;//一天的總秒數

	// 獲取當前時間
	time( &rawtime );
	nowdate = *localtime( &rawtime );
	nowdate.tm_mon = nowdate.tm_mon+1;
	printf("now year:%d, month:%d, day:%d\n",  nowdate.tm_year,  nowdate.tm_mon,  nowdate.tm_mday);

	// 給出指定時間
	setdate = *localtime( &rawtime );
	setdate.tm_hour = 0; setdate.tm_min = 0; setdate.tm_sec=0;
	setdate.tm_mon = 1; setdate.tm_mday = 1; setdate.tm_year = 114;//2014-1900
	printf("modify now year:%d, month:%d, day:%d\n", setdate.tm_year, setdate.tm_mon, setdate.tm_mday);

	// 計算兩個時間點之間的間隔秒數
	dftime = difftime(mktime(&nowdate), mktime(&setdate));
	printf("dftime=%ld, daysecond=%ld, result=%ld\n", dftime, daysecond, dftime / daysecond);
	*diffday/*天數*/ = (int)floor(dftime / daysecond);//通過計算秒數來確定所給天數（總秒數/一天所含秒數=天數）
	return 0;
}