C: Create semi-open interval [min, max).

gistfile1.c

// Create semi-open interval [min, max).
int random_in_range(unsigned int min, unsigned int max) {
  int base_random = ::rand(); // in [0, RAND_MAX]
	if (RAND_MAX == base_random) {
		return random_in_range(min, max);
	}

	// Now guaranteed to be in [0, RAND_MAX).
	int range = max - min;
	int remainder = RAND_MAX % range;
	int bucket = RAND_MAX / range;

	// There are range buckets, plus one smaller interval
	// within remainder of RAND_MAX.
	if (base_random < RAND_MAX - remainder) {
		return min + base_random / bucket;
	} else {
		return random_in_range(min, max);
	}
}