c++ - std::mt19937 doesn't return random number -

i have following piece of code:

unsigned int randomint() {     mt19937 mt_rand(time(0));     return mt_rand(); }; 

if call code, example 4000 times in loop, don't random unsigned integers, instead example 1000 times 1 value , next 1000 times next value.

what doing wrong?

this happens because call f 4000 times in loop, takes less mili second, @ each call time(0) returns same value, hence initializes pseudo-random generator same seed. correct way initialize seed once , all, preferably via std::random_device, so:

#include <random> #include <iostream>  static std::random_device rd; // random device engine, based on /dev/random on unix-like systems // initialize mersennes' twister using rd generate seed static std::mt19937 rng(rd());   int dice() {     static std::uniform_int_distribution<int> uid(1,6); // random dice     return uid(rng); // use rng generator }  int main() {     for(int = 0; < 10; ++i)         std::cout << dice() << " ";    }