預計初始化*令牌

Question

所以我有這個頭文件：

#pragma once 

#include "engine.hpp" 

namespace spacecubes 
{ 
    extern engine* _engine; 
} 

和包括engine.hpp：

#pragma once 

#include <iostream> 

#include "glinclude.hpp" 
#include "debug.hpp" 
#include "convert.hpp" 
#include "renderer.hpp" 
#include "global.hpp" 

namespace spacecubes { 
    void display(); 

    class engine { 
     renderer renderengine; 

    public: 
     void start(int argc, char* argv[]); 
     void stop(int status = 0); 
     void poll(); 

     renderer getRenderEngine() {return renderengine;} 
    }; 
} 

編譯報導什麼以後是：

g++ -c -o bin/obj/engine.o src/engine.cpp 
In file included from src/engine.hpp:9, 
       from src/engine.cpp:1: 
src/global.hpp:7: error: expected initializer before '*' token 
src/engine.cpp: In function 'void spacecubes::display()': 
src/engine.cpp:5: error: '_engine' was not declared in this scope 

我不明白。這是什麼意思，它預計初始化？提前致謝！

Answer 1

與向前聲明替換

#include "engine.hpp" 

：

namespace spacecubes { class engine; }