How to initialize an unsigned long long type?

unsigned long  buf[254];

snprintf(systemlogmsg, sizeof(systemlogmsg), "INFO: %lu ",  buf[0]);  // ok

int s = 0, i;
for (i=0; i< 254; i++)
  s+=snprintf(systemlogmsg+s, 
       sizeof(systemlogmsg)-s, "INFO: %lu ",  buf[i]);  // ok

if(number<0)
{
    void Calculate_neg_power(number,expo);
}
else{
    void Calculate_pos_power(number,expo);
}

if(number<0)
{
    Calculate_neg_power(number,expo);
}
else{
    Calculate_pos_power(number,expo);
}

int Driver(NUMBER,EXPO, ans);

size_t N;

fscanf(txt, "%zu", &N);

memset(dist, LONG_MAX, N*sizeof(long int));

void *memset(void *s, int c, size_t n);