Ez miért nem jó? C++

# include <iostream>

using namespace std;

const macska &functiontwo ( const macska &morcos2 );

class macska

{

public:

macska() { cout <<"macska konstruktor \n"; itsAge = 1; }

macska(macska&) { cout <<"macska masolo konstruktor \n"; }

~macska() { cout <<"macska destruktor \n"; }

void Bage(short age) { itsAge = age; }

short Vage() const { return itsAge; }

private:

short itsAge;

};

int main()

{

cout <<"Macska letrehozasa \n";

macska morcos;

cout <<"morcos " << morcos.Vage() <<" eves \n";

short age = 4;

morcos.Bage(age);

cout <<"morcos " << morcos.Vage() <<" eves \n";

functiontwo(morcos);

cout <<"morcos " << morcos.Vage() <<" eves \n";

std::cin.clear();

std::cin.get();

return 0;

}

const macska &functiontwo ( const macska &morcos2)

{

cout <<"functiontwo returning \n";

cout <<"morcos most " << morcos2.Vage() <<" eves \n";

// morcos2.Bage(8); nem mukodik (const)!!!

return morcos2;

}