Function Hiding

#include <iostream>
using namespace std;

class Base {
public:
    void fun()
    {
        cout << "void" << endl;
    }

    void fun(int i)
    {
        cout << "Base" << endl;
    }
};

class Derived : public Base {
public:
    //using Base::fun; // comment/uncomment this line

    int fun(char c)
    {
        cout << "Derived" << endl;
        return 0;
    }
};

int main()
{
    Derived d;

    //d.fun(); // error unless uncomented 'using' line in Derived class
    d.Base::fun();

    d.fun(1);
    d.Base::fun(1);

    d.fun('a');

    return 0;
}