头文件
time_t now ;
struct tm *tm_now ;
time(&now) ;
tm_now = localtime(&now) ;
printf("now datetime: %d-%d-%d %d:%d:%d\n", tm_now->tm_year+1900, tm_now->tm_mon+1, tm_now->tm_mday, tm_now->tm_hour, tm_now->tm_min, tm_now->tm_sec) ;