C/C++ :: Using Class Parameter In Virtual Class

I am trying to create a platformer and is stuck on a problem regarding my virtual class Entity. I wish to use it to create stuff like the Player and Enemy class(es). But how to do the parameter for my collision check function. Below is my Entity- and player class.

There might be a better way to check CC with a lot of different objects, this is my first attempt.

This is the error I am getting: "error C2664: 'bool Player::CollisionCheck(Hostile)' : cannot convert argument 1 from 'Player' to 'Hostile'"

#ifndef ENTITY_H
#define ENTITY_H
#include <SFMLGraphics.hpp>
class Entity {
public:
Entity();
Entity(sf::Vector2f position, sf::Vector2f size, sf::Color fillColor, sf::Color outlineColor);

[Code] ....

and in Hostile I would (I guess) use
bool CollisionCheck(Player p);

But if I try for example to use Player in the CC in player.h it will complain that the function doesn't have an overload for that. Hostile is just a example class name right now, it isn't implemented yet. I am trying to use Player, but if possible wish to be able to have a different class depending on what kind of entity it is. The entity will probably also be the players projectiles and so on.