在C ++中的循环引用[复制](Circular Reference in C++ [duplicate])

 
 
 这个问题在这里已经有了答案： 
 
 
 
  
 解决由于类之间的循环依赖关系造成的错误 8个答案 
 
 
 
 
 我正在做一个Snake游戏，并且我在C ++中遇到了Circular Reference的问题。 这是SnakeBody类的头部，代表Snake的任何部分，而不是头部。 
 
#ifndef SNAKEBODY_HPP_
#define SNAKEBODY_HPP_

class SnakeBody {
    public:
        SnakeBody(SnakeHead *origin, int left, int x, int y);
        ~SnakeBody() = default;
        void move();
        void grow(int size);
    protected:
        SnakeBody *next;
        SnakeHead *head;
        SnakeGame *game;
        int x;
        int y;
        int growWait;
};

#endif /* !SNAKEBODY_HPP_ */
 
 还有源代码（包含构造函数的部分）。 
 
#include "../include/SnakeHead.hpp"
#include "../include/SnakeGame.hpp"
#include "../include/SnakeBody.hpp"

SnakeBody::SnakeBody(SnakeHead *origin, int left, int x, int y)
{
    this->head = origin;
    this->game = this->head->getGame();
    this->x = x;
    this->y = y;
    this->growWait = 0;
    if (left > 0)
        this->next = new SnakeBody(origin, left - 1, x + 1, y);
    else
        this->next = nullptr;
}
 
 我一直在关心如何使每个包含在源代码中而不是标题中，以避免未完成的引用和循环。 但它仍然显示SnakeHead有一个未定义的参考。 
 
 SnakeBody：蛇的任何部分不是头部。 SnakeHead：蛇的头。 SnakeGame：包含棋盘的状态，需要SnakeHead和SnakeHead的参考，而SnakeBody需要SnakeGame的参考来获取有关游戏状态的数据（例如墙壁，食物等）。 
 
 错误消息是：./src/../include/SnakeBody.hpp:19:9：错误：'SnakeHead'没有命名一个类型; 你的意思是'SnakeBody'吗？ SnakeHead *头; 

 
 
This question already has an answer here:
 
 
 
  
 Resolve build errors due to circular dependency amongst classes  11 answers  
 
 
 
 
i'm working on a Snake game and i'm having trouble with Circular Reference in C++. This is the header of the class SnakeBody who represent anypart of the Snake that is not the head.
 
#ifndef SNAKEBODY_HPP_
#define SNAKEBODY_HPP_

class SnakeBody {
    public:
        SnakeBody(SnakeHead *origin, int left, int x, int y);
        ~SnakeBody() = default;
        void move();
        void grow(int size);
    protected:
        SnakeBody *next;
        SnakeHead *head;
        SnakeGame *game;
        int x;
        int y;
        int growWait;
};

#endif /* !SNAKEBODY_HPP_ */
 
And there is the source code (the part containing the constructor).
 
#include "../include/SnakeHead.hpp"
#include "../include/SnakeGame.hpp"
#include "../include/SnakeBody.hpp"

SnakeBody::SnakeBody(SnakeHead *origin, int left, int x, int y)
{
    this->head = origin;
    this->game = this->head->getGame();
    this->x = x;
    this->y = y;
    this->growWait = 0;
    if (left > 0)
        this->next = new SnakeBody(origin, left - 1, x + 1, y);
    else
        this->next = nullptr;
}
 
I have been carefull about make every include in source and not header to avoid unfinished reference and loop. But it still appear that SnakeHead has a undefined reference.
 
SnakeBody : Any part of the snake that is not the head. SnakeHead : The head of the snake. SnakeGame : Contain the state of the board, need a reference of SnakeHead and SnakeHead and SnakeBody need a reference of SnakeGame to get data about the state of the game (ie : wall, food, etc...).
 
The error message is : ./src/../include/SnakeBody.hpp:19:9: error: ‘SnakeHead’ does not name a type; did you mean ‘SnakeBody’? SnakeHead *head;

原文：https://stackoverflow.com/questions/49684818