C ++未声明的标识符错误 [英] C++ undeclared identifier error

问题描述

我收到一个未声明的标识符错误，我不知道为什么.我什至重写了完整的内容，以确保我没有打错字.有人可以告诉我为什么会出现此错误吗?

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 this error?

我的文件是

Connection.hpp

#pragma once

#include "../LogicSimulator.hpp"
#include "CircuitObject.hpp"

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

不要介意 CircuitObjects ，它们不会发出任何错误，错误是:未声明的"LogicSimulator"

Don't mind the CircuitObjects, they don't give out any errors, errors are: undeclared 'LogicSimulator'

Connection.cpp

#pragma once

#include "Connection.hpp"
#include "../LogicSimulator.hpp"
#include "CircuitObject.hpp"

Connection::Connection(CircuitObject& c1, CircuitObject& c2, LogicSimulator& 
    simulator) : c1(c1), c2(c2), simulator(simulator)
{
    state = c1.State;
}

错误:未声明'LogicSimulator'

Errors: undeclared 'LogicSimulator'

LogicSimulator.hpp

#pragma once

#include "Simulator\CircuitObject.hpp"
#include "Simulator\Connection.hpp"
#include <SFML\Graphics.hpp>
#include <vector>

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();
};

不要介意LogicSimulator.cpp，它不会发出任何错误.

Don't mind LogicSimulator.cpp, it doesn't give out any errors.

错误:未声明连接"(是的，并且在连接LogicSimulator中未声明)

Errors: undeclared 'Connection' (Yeah, and in Connection LogicSimulator is undeclared)

推荐答案

正如我在评论中所写，这很可能是由您的通函包含引起的. Connection.hpp 包括 LogicSimulator.hpp ，它本身也包含 Connection.hpp .

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.

就您而言，您甚至不需要包含.对于指针和引用，可以使用向前声明:

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

Connection.hpp:

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:

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();
};

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