C++ Have a function repeat in the background

Question

I am using microsoft visual express.

I have viewed the accepted answer for this question and it seems to not be doing what I want it to do.

This is the function

Answer 1

What you want is a std::thread as I mentioned in my comment. But also note you need a synchronization mechanism to prevent concurrent access for your global variables:

double time_counter = 0;
clock_t this_time = clock();
clock_t last_time = this_time;
const int NUM_SECONDS = 1;
std::mutex protect; // <<<<
void repeat() {
    while (1) {
        this_time = clock();

        time_counter += (double)(this_time - last_time);
        last_time = this_time;
        if (time_counter > (double)(NUM_SECONDS * CLOCKS_PER_SEC)) {
            time_counter -= (double)(NUM_SECONDS * CLOCKS_PER_SEC);
            std::lock_guard lock(protect); // <<<<
            rockSecPast++;
        }
    }
}

and do the same in your main thread

std::thread t(repeat);
t.detach();

// ....

int currentRockSecPast = 0;
{
    // read the asynchronously updated value safely
    std::lock_guard lock(protect);
    currentRockSecPast = rockSecPast; 
}

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_{If I were you I'd put all that mess from above together in a separate class.}