Generating a random number without random function

i need to generate a random number without using "random" function so i found this code which give me mlliseconds in system:

#include <stdio.h>
#include <sys/timeb.h>

int main()
{
struct timeb tmb;

ftime(&tmb);
printf("tmb.time     = %ld (seconds)\n", tmb.time);
printf("tmb.millitm  = %d (mlliseconds)\n", tmb.millitm);

return 0;
}

it was working good until i tried to use it inside struct in this way :

#include <sys/timeb.h>
#include "stdlib.h"
struct Num{
struct timeb tmb;
ftime(&tmp);    
};
int main()
{

return 0;
}

its giving an error at {ftime}. any help ?