This question is a direct follow-up of:

Have a look at this Mersenne Twister random-number generator function

Thanks to Code Review and Stack Overflow, I now realize, that:

• unsigned long long int is not guaranteed to be 64-bit

• I don’t want to re-initialize the random_device on every function call

and a few other things.

So, based on current information, I’ve re-written it as follows:

#include <iostream>     // std::cout #include <cstdint>      // std::uint64_t #include <random>       // std::random_device, etc.  std::uint64_t random_integer(std::uint64_t rand_min, std::uint64_t rand_max) {     // use Mersenne Twister as random-number generator engine     // initialize = seed the random device; static thread_local = only once     // avoid "most vexing parse" by using "uniform initialization syntax" = { something{}() }     static thread_local std::mt19937_64 random_number_generator{std::random_device{}()};      // uniform number distribution, guaranteed unbiased     std::uniform_int_distribution<std::uint64_t> number_distribution(rand_min, rand_max);      // return one random number     return number_distribution(random_number_generator); }  // this is just to test the output int main() {     for (int i = 1; i <= 10; i++)     {         std::cout << random_integer(10000000, 100000000) << std::endl;     }     return 0; } 

If you could guide me further on improving it, I would be grateful.