时间如何提前8个小时

#include <time.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/timeb.h>
#include <string.h>

void main()
{
    time_t ltime;
    struct tm *today;
 
    time( &ltime );
    ltime -= 8*3600;
    today = localtime( &ltime );

}