C++ undeclared identifier error

Question

I\'m getting an undeclared identifier error and I don\'t know why. I even rewrote the complete stuff to make sure I didn\'t do a typo. Can someone tell me why I got thi

Answer 1

This is, as I wrote in the comments, most likely caused by your circular includes. Connection.hpp includes LogicSimulator.hpp which itself includes Connection.hpp.

In your case, you don't even need the includes. For Pointers and References, a forward declaration is fine:

Connection.hpp:

#pragma once

class CircuitObject;
class LogicSimulator;

class Connection
{
public:
    Connection(CircuitObject& c1, CircuitObject& c2, LogicSimulator& 
        simulator);
private:
    int state;
    CircuitObject& c1;
    CircuitObject& c2;
    LogicSimulator& simulator;
};

LogicSimulator.hpp:

#pragma once

#include <SFML\Graphics.hpp>
#include <vector>

class CircuitObject;
class Connection;

class LogicSimulator
{
public:
    std::vector<CircuitObject*> circuitObjects;
    std::vector<CircuitObject*> selectedCircuitObjects;
    std::vector<Connection*> connections;
    sf::RenderWindow Window;

    void Init();
private:
    void start();
    void draw();
};