前向声明继承并包含 |不完整的类型或预期的 class 名称

Question

有人可以帮忙吗？

假设，我有以下 C++ 文件：

Room.h

#ifndef ROOM_H
#define ROOM_H

#include "Console.h"

...

class Room {
public:
   void room();
};

#endif // ROOM_H

Room.cpp

#include "Room.h"

void Room::room() {
  Console::print();
}

Console.h

#ifndef CONSOLE_H
#define CONSOLE_H

#include "Room.h"
#include "RoomChild.h"

class Console {
public:
   static void print();
   static void printRoom(Room& room);
   static void printRoomChild(RoomChild& room);
};

#endif // CONSOLE_H

Console.cpp

#include "Console.h"

void Console::print() {
    ;
}

void Console::printRoom(Room& room) { 
    // print member of room 
}

void Console::printRoomChild(RoomChild& roomChild) { 
    // print member of roomChild 
}

RoomChild.h

#ifndef ROOM_CHILD_H
#define ROOM_CHILD_H

#include "Room.h"
#include "Console.h"

class RoomChild : public Room {
public:
    void roomChild();
};

#endif // ROOM_CHILD_H

RoomChild.cpp

#include "RoomChild.h"

void RoomChild::roomChild() {
    Console::print();
}

我的问题是

是否可以让它工作？

我已尝试向每个 class 或仅向其中一些人提出声明。但是，它不起作用并给我 ... has incomplete type 或 expected class-name before '{' token class RoomChild: public Room {

Answer 1

包括的都搞砸了。

从不相关的文件中删除多余的包含指令。

在它们所依赖的文件上添加 include 指令。

Room.h

#ifndef ROOM_H
#define ROOM_H

/* DELETE: because Room.h does not depend on it.
#include "Console.h"
*/

// ...

class Room {
public:
   void room();
};

#endif // ROOM_H

Room.cpp

#include "Room.h"

/* ADD: because Room.cpp does depend on it. */
#include "Console.h"

void Room::room() {
  Console::print();
}

Console.h

#ifndef CONSOLE_H
#define CONSOLE_H

/* DELETE: because Console.h does not depend on them.
#include "Room.h"
#include "RoomChild.h"
*/

class Console {
public:
   static void print();
};

#endif // CONSOLE_H

Console.cpp

#include "Console.h"

void Console::print() {
    ;
}

RoomChild.h

#ifndef ROOM_CHILD_H
#define ROOM_CHILD_H

#include "Room.h"
/* DELETE: because RoomChild.h does not depend on it
#include "Console.h"
*/

class RoomChild : public Room {
public:
    void roomChild();
};

#endif // ROOM_CHILD_H

RoomChild.cpp

#include "RoomChild.h"
/* ADD: because RoomChild.cpp does depend on it. */
#include "Console.h"

void RoomChild::roomChild() {
    Console::print();
}