/* itob(n,s,b) * converts the integer n into a base b char */void itob(int n, char s[], int b){    static char digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";    int i, sign;    if ( b < 2 || b > 36 ) {             fprintf(stderr, "EX3_5: Cannot support base %d\n", b);                  exit(EXIT_FAILURE);    }    if ((sign = n) < 0)             n = -n;    i = 0;    do {             s[i++] = digits[n % b];    } while ((n /= b) > 0);    if (sign < 0)             s[i++] = '-';    s[i]='\0';    reverse(s);}