Is there a possibility to use cin parallel to cout?

问题

I'm trying to write a program in C++ which will be responsible for simulating blinkers in cars. I want it to be simple and to compile it in a console window.

Is it possible to create one thread for input which will be always active and second for output that will run simultaneously?

I wanted to use threads to solve this but it doesn't work as I would like. I have a little trouble to understand threads. If anyone could help me to fix this I would be grateful.

int in()
{
    int i;
    cout<<"press 1 for left blinker or 0 to turn it off: ";
    cin>>i;
    return i;
}

void leftBlinker()
{
    int i;
    cout << "<-";
    Sleep(1000/3);
    cout << "  ";
    Sleep(1000/3);

}


int main()
{
    thread t1 (in);


    if (in()==1)
    {
        for (int i=0; i<100; i++)
        {
            thread t2(leftBlinker);
            if (in()==0)
                break;
        }
    }

    system("pause");
    return 0;
}

回答1:

Here is a simple example code:

#include <atomic>
#include <chrono>
#include <iostream>
#include <thread>

int in(std::atomic_int &i) {
  while (true) {
    std::cout << "press 1 for left blinker or 0 to turn it off: ";
    int input;
    std::cin >> input;
    i = input;
  }
}

void leftBlinker(std::atomic_int &i) {
  while (true) {
    if (i) {
      std::cout << "<-" << std::endl;
      std::this_thread::sleep_for(std::chrono::milliseconds{333});
      std::cout << "  " << std::endl;
      std::this_thread::sleep_for(std::chrono::milliseconds{333});
    }
  }
}

int main() {
  std::atomic_int i{0};
  std::thread t1(in, std::ref(i));
  std::thread t2(leftBlinker, std::ref(i));

  t1.join();
  t2.join();
  return 0;
}

A reference to std::atomic_int is passed to both functions for communication. std::atomic_int ensures thread-safe reads and writes. At the end you should join or detach the threads.

来源：https://stackoverflow.com/questions/61275142/is-there-a-possibility-to-use-cin-parallel-to-cout

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c++

printf

cin

cout