如何从静态成员函数返回副本？

Question

What's wrong with my static topStock method? It takes in a reference to Stock s and Stock t. Shouldn't it return a copy of s or t?

error: expected primary-expression before '.' token|

#include <iostream>

using namespace std;

class Stock {

public:

    Stock() : x(0){ }
    Stock(int val) : x(val){}

    void display() const;

    static Stock topStock(const Stock& s, const Stock& t) {
     if (s.x > t.x)
        return s;
    else
        return t;
    }

    int x;
};

void Stock::display() const
{

    std::cout << this->x;

}


int main()
{
    Stock s(9);
    Stock y(8);
    Stock z = Stock.topStock(s, y);
    return 0;
}

Answer 1

Change

Stock.topStock(s, y);

to

Stock::topStock(s, y);

because it is a static member function.