c++11线程类如何使用类成员函数

Question

我的程序如下所示

#include <iostream>
#include <thread>

class A {
public:
    void foo(int n ) { std::cout << n << std::endl; }
};

int main()
{
    A a;

    std::thread t1(&A::foo, std::ref(a), 100);

    t1.join();
    return 0;
}

当我使用以下命令编译它时，我得到了错误

g++ -o main main.cc -lpthread -std=c++11

错误:

In file included from /usr/local/include/c++/4.8.2/thread:39:0,
                  from check.cc:2:
/usr/local/include/c++/4.8.2/functional: In instantiation of ‘struct std::_Bind_simple<std::_Mem_fn<void (A::*)(int)>(std::reference_wrapper<A>, int)>’:
/usr/local/include/c++/4.8.2/thread:137:47:   required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (A::*)(int); _Args = {std::reference_wrapper<A>, int}]’
check.cc:13:42:   required from here
/usr/local/include/c++/4.8.2/functional:1697:61: error：no type named ‘type’ in ‘class std::result_of<std::_Mem_fn<void (A::*)(int)>(std::reference_wrapper<A>, int)>’
        typedef typename result_of<_Callable(_Args...)>::type result_type;
                                                              ^
/usr/local/include/c++/4.8.2/functional:1727:9: error：no type named ‘type’ in ‘class std::result_of<std::_Mem_fn<void (A::*)(int)>(std::reference_wrapper<A>, int)>’
          _M_invoke(_Index_tuple<_Indices...>)
          ^

Answer 1

这不是引用包装器的正确位置。不过，一个简单的指针就足够了，并且可以达到预期的效果:

std::thread t1(&A::foo, &a, 100);