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我似乎很难理解下面的代码有什么问题。该程序运行正确，但在行

startCounter.join();

我的程序似乎崩溃了，错误代码为 EXC_BAD_ACCESS（代码=13，地址=0x0）。我正在使用 XCode。

直到该行正常工作为止的所有内容；当另一个线程无限期地递增该值时，程序每秒打印出 n 的值。我究竟做错了什么？

#include <iostream>
#include <boost/thread.hpp>

boost::mutex mtx;

class Worker
{
public:
    Worker(int n);
    void increment();
    void printValue();
private:
    int n;
};

int main()
{
    Worker test(5);

    boost::thread startCounter(boost::bind(&Worker::increment, &test));
    std::cout << "Increment Thread Started..." << std::endl;

    boost::thread startPrinter(boost::bind(&Worker::printValue, &test));
    std::cout << "Print Thread Started..." << std::endl;

    startPrinter.join();
    startCounter.join();

    std::cout << "Program Complete." << std::endl;

    return EXIT_SUCCESS;
}

Worker::Worker(int n) : n(n)
{
    std::cout << "Initial Value: " << n << std::endl;
}

void Worker::increment()
{
    for (int i = 0; i < 60000000; i++) {
        boost::lock_guard<boost::mutex> lock(mtx);
        n = i;
    }

    std::cout << "Increment Thread Finished. Final Value: " << n << "." << std::endl;
}

void Worker::printValue()
{
    for (int i = 0; i < 10; i++) {
        {
            boost::lock_guard<boost::mutex> lock(mtx);
            std::cout << "Current value: " << n << std::endl;
        }
        boost::this_thread::sleep(boost::posix_time::milliseconds(1000));
    }

    std::cout << "Print Thread Finished." << std::endl;
}

非常感谢！

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