How Would I Make A Random Seed/Hash To Make Rand Actually Random? [duplicate]

Question

how would i generate a seed or hash that would make rand actually random? I need it to change every time it picks a number. New to c++ so i'm not exactly sure how to do this. Thanks! :D

Answer 1

With C++11 you can use std::random_device. I would suggest you to watch link for a comprehensive guide.

Extracting the essential message from the video link : You should never use srand & rand, but instead use std::random_device and std::mt19937 -- for most cases, the following would be what you want:

#include <iostream>
#include <random>
int main() {
    std::random_device rd;
    std::mt19937 mt(rd());
    std::uniform_int_distribution<int> dist(0,99);
    for (int i = 0; i < 16; i++) {
        std::cout << dist(mt) << " ";
    }
    std::cout << std::endl;
}

Answer 2

There is no such thing as an "actually random" random number generator without sampling environmental data or accessing a quantum random number source. Consider accessing the ANU random number source if you require truly random numbers (http://qrng.anu.edu.au/FAQ.php#api).

Otherwise, Boost provides a more robust pseudo-RNG, which should suffice for most purposes: http://www.boost.org/doc/libs/1_58_0/doc/html/boost_random.html