/* Using example 3 Shuffle the contents of a vector and an array see: https://msdn.microsoft.com/en-us/library/bb982398.aspx */ #include #include #include #include #include #include #include // huh needs research... using namespace std; template void print(const C& c) { for(const auto& e : c) { cout << e << " "; } cout << endl; } template void test(URNG& urng) { //uniform distribution used with a vector //Distribution is [-10, 10] inclusive uniform_int_distribution dist(-10, 10); vector v; for(int i = 0 ; i < 20; ++i){ v.push_back(dist(urng)); } cout << "Randomized Vector: "; print(v); // Shuffle an Array // Note: shuffle() takes a URNG, not a distribution array arr = { { "H", "He", "Li", "Be", "B", "C", "N", "O", "F", "Ne", "Na", "Mg", "Al", "Si", "P", "S", "Cl", "Ar", "K", "Ca", "Sc", "Ti", "V", "Cr", "Mn", "Fe" } }; shuffle(arr.begin(), arr.end(), urng); cout << "Randomized Array: "; print(arr); cout << " -- " << endl; } int main() { // First run: Non-seedable, non-deterministic URNG random_device // Slower but crypto-secure and non-repeatable random_device rd; cout << "Using random_device URNG: " << endl; test(rd); //Second run: simple integer seed, repeatable results cout << "Using constant-seed mersenne twister URNG: " << endl; mt19937 engine1(12345); test(engine1); //Third run: random_device as a seed. Different each run // Desirable for most purposes cout << "Using non-deterministic-seed mersenne twister URNG: " << endl; mt19937 engine2(rd()); test(engine2); //Forth run: "warm-up" sequence as seed, different each run // Advanced uses. Allows more than 32bits of randomness cout << "Using non-deterministic-seed \"warm-up\" sequence mersenne twister URNG: " << endl; array seed_data; generate_n(seed_data.begin(), seed_data.size(), ref(rd)); seed_seq seq(begin(seed_data), end(seed_data)); mt19937 engine3(seq); test(engine3); return 0; }

Using Random #3