C++ konštantná funkcia triedy

#include <iostream>

class CTested
{
public:
    int param;
    int getParamOf(const CTested & cTested); / tu...
    const int getParam();
};

int CTested::getParamOf(const CTested & tested)
{
    return tested.getParam();
}

const int CTested::getParam()
{
    return param;
}

int main()
{
    CTested c, c2;
    c.param = 5;
    c2.param = 10;
    std::cout << c.getParam() << "\n";
    std::cout << c2.getParamOf(c) << "\n";
    std::cin.get();
}

int getParam() const;

int CTested::getParam() const {...}