I want two loops to run in parallel

Question

Here is what I'm trying to do, I want a part of code in main() to run on a continuous loop to check the input and other things. And another part of code to run on delay of every X milliseconds.

while(true) //want this to run continuously, without any delay.
{
    Input();
}

while(true) //want this to run every 1500 miliseconds.
{
    DoSomething();
    Sleep(1500); //from <windows.h> library.
}

Is there any way to do this properly?

Does this answer your question? [Simple example of threading in C++](https://stackoverflow.com/questions/266168/simple-example-of-threading-in-c) — Richard Critten, Dec 29 '19 at 20:10
What's the target system? Many OSes have the ability to do this without threads, for example Overlapped IO in Windows. or `epoll` or `select` with a timeout on Linux. — user4581301, Dec 29 '19 at 20:18

score 6 · Answer 1 · answered Dec 29 '19 at 20:12

You'll want to run two threads:

void f()
{
    while(true) //want this to run continuously, without any delay.
    {
        Input();
    }
}

void g()
{    
    while(true) //want this to run every 1500 miliseconds.
    {
        DoSomething();
        Sleep(1500); //from <windows.h> library.
    }
}

int main()
{
    std::thread t1(f);
    std::thread t2(g);
    ...

score 0 · Answer 2 · answered Dec 30 '19 at 12:46

I used high_resolution_clock to keep track of time. I used simple while loop for continuous update and added if condition to do some specific task, after a time interval.

#include<chrono> //For clock
using namespace std::chrono;

high_resolution_clock::time_point t1, t2;

int main()
{
    t1 = high_resolution_clock::now();
    t2 = {};

    while(true)
    {
        CheckInput(); //Runs every time frame

        t2 = high_resolution_clock::now();

        if(duration_cast<duration<float>>(t2 - t1).count()>=waitingTime)
        {
            DoSomething();  //Runs every defautWaitTime.
            t1 = high_resolution_clock::now();
            t2 = {};
        }
    }
    return 0;
}

I want two loops to run in parallel

2 Answers2