- Solution

#include <chrono>
#include <iostream>
#include <thread>
class Sleeper{
  public:
    Sleeper(int& i_, int m):i{i_}, milli(m){};
    void operator() (int k){
      for (unsigned int j = 0; j <= 5; ++j){
        std::this_thread::sleep_for(std::chrono::milliseconds(milli));
        i += k;
      }
    }
  private:
    int& i;
    int milli;
};
int main(){
  std::cout << std::endl;
  for (unsigned int i = 0; i <= 20; ++i){
    int valSleeper = 1000;
    std::thread t(Sleeper(valSleeper, (i*50)), 5);
    t.detach();
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
    std::cout << "valSleeper = " << valSleeper << std::endl;
  }
  std::cout << std::endl;
}