Can't do async run member function in other class

Question

I try to async to member function in other class but can't. this is overview in my code

#include <iostream>
#include <thread>
#include <future>
#include <vector>

using namespace std;
class Work
{
public:
    void doWork(int A);
};

 void Work::doWork(int A)
{
    cout<<"I got "<<A<<endl;    
}   

class Worker
{
private:
    vector<int> work_list;
    Work* workset = NULL;
public:
    void Work_MP();
};
void Worker::Work_MP()
{
    vector<std::future<void>> v_async;
    v_async.reserve(8);
    for (size_t i = 0; i < 8; i++)
    {   
        Work* workset = new Work();
        v_async.emplace_back(std::async(std::launch::async, &Work::doWork, &workset, i));
    }   
}

int main ()
{
}

Although, I give pointer about other class function and instance. didn't work. Is other needed statement missing?

Answer 1

I tried to fix your code and came up with a version that is working. You have a lot of unecessary cluttering in there. Also your code will leak the workset pointer. As pointed out in the comments the main mistake was the &workset which created a "ref to pointer" where all you need was the pointer itself. You should avoid the plain pointers altogether. This is what I came up with, hope it helps:

#include <vector>
#include <future>
#include <iostream>

class Work
{
public:
    void doWork(int A){
        std::cout << "I got " << A << std::endl;    
    }
};

class Worker
{
public:
    void Work_MP(){
        std::vector< std::future<void> > v_async;
        v_async.reserve( 8 );
        for( size_t i = 0; i < 8; ++i ){   
            std::shared_ptr<Work> workset = std::make_shared<Work>();
            v_async.emplace_back( std::async( std::launch::async, &Work::doWork, workset, i ) );
        }  
    }
};

int main ()
{
    Worker worker;
    worker.Work_MP();
    return 0;
}

As you can see I inlined the function definition for briefness. Converted the plain pointer to shared pointer and removed unused vars.

See it in action here: https://onlinegdb.com/vFQo8R1rA