子类中的虚拟函数调用父函数一次

这个问题似乎与线程和运行程序的速度非常快有关。我有 2 个类，ThreadParent 个类和ThreadChild类，一个从另一个继承。 ThreadParent创建一个线程并运行函数func，声明为静态以规避指针问题。但是，我确实希望继承的类（例如ThreadChild）决定线程究竟做什么，func调用虚拟函数Do。

但是，当创建ThreadChild对象并立即运行线程调用时，ThreadParent::Do开始时调用一次，并且所有后续调用都将ThreadChild::Do。有趣的是，当我在打电话之前等待Do时，它不会发生。

有没有比等待更好的解决方案？更重要的是，为什么会发生这种情况？

这是一个小而完整的示例。它创建一个ThreadChild对象，每 200 毫秒执行一次Do。程序在 1 秒后结束（等待进入按）。

#include <iostream>
#include <windows.h>
#include <thread>
// The parent class
class ThreadParent {
protected:
    bool _loopThread; //setting this to false should end the thread
    std::thread _thread; //the thread
public:
    // Basic constructor
    ThreadParent(ThreadParent* child)
        : _loopThread(true),
        _thread(func, child, &_loopThread) {}
    // Stops the thread and waits for it to finish
    void StopThread() {
        _loopThread = false;
        _thread.join();
    }
protected:
    // The function the thread will be running (static because of pointer issues)
    static void func(ThreadParent* child, bool* loopThread) {
        //Sleep(10); //<- uncomment to solve the problem?
        while (*loopThread) {
            child->Do(); // Do is called every 200ms
            Sleep(200);
        }
    }
    // The function which is called repeatedly until _loopThread is set to false
    virtual void Do() {
        std::cout << "Parent calln";
    }
};
// The child class
class ThreadChild : public ThreadParent {
public:
    // Basic constructor
    ThreadChild()
        : ThreadParent(this) {}
protected:
    // Redefines Do() with another message
    void Do() {
        std::cout << "Child calln";
    }
};
// The program
int main() {
    ThreadChild thread;  // Create and run the thread
    Sleep(1000);         // Run the thread for 1s
    thread.StopThread(); // End it
    std::cout << "Press <enter> to terminate...";
    std::cin.get(); // Wait for user to end program
    return 0;
}

输出：

Parent call
Child call
Child call
Child call
Child call
Press <enter> to terminate...