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

std::atomic<double> counter{0};

void some_thread()
{
    for(unsigned i=0; i<1000; ++i)
    {
        //++counter; // Does not compile
        for(double v = counter.load(); counter.compare_exchange_weak(v, v+1)==false; )
            {}
        std::cout << '\b';
    }
}

int main()
{
    std::thread t1(some_thread), t2(some_thread);
    t1.join();
    t2.join();
    std::cout << "counter = " << counter << std::endl;
}