C++ class method that take instance of the same class

Im new to c++, I'm trying to have a class that has a method that take an instance of it self. Here what I'm try to achieve.

Class A {

public:

std::vector<int>* getData(){return &data;}

// I need to merge the data from 2 class, so in my code 
//I can call p.merge(c) where p&c instance of A

void Merge (A ptr) {
   data = ptr->getData()->data;
}

private:

std::vector<int> data;

}

Any idea how to do the merge function.