头文件

#include<time.h>

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) ;