unique id generator

unique_id_generator.c

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

int main()
{
        int i;
        for(i =0;i < 32; i++)
                func(i);
        return 0;
}
int func(unsigned long u_id)
{
        struct timeval t;
        unsigned long id;
        gettimeofday(&t,NULL);
        id = (t.tv_sec * 1000 * 1000) + (t.tv_usec * 1000) << 42;
        id |= (u_id % 16777216) << 24;
        printf("%lu\n ",id);
        return 0;
}