包含问题 [英] A problem with include

问题描述

//Class1.h
#include "Class3.h"
class Class1 { ... };

//Class2.h
#include "Class1.h" // error C2504: 'Class1' : base class undefined
class Class2 : public Class1 { ... };

//Class3.h
#include "Class2.h"
class Class3 { ... };

我该如何解决.非常感谢.

How can I solve this. Thanks a lot.

推荐答案

那是因为您没有仔细阅读我的回复.

您需要从Class1.h中删除#include "Class3.h"，并从Class3.h中删除#include "Class2.h".

-Saurabh

That is because you didn''t read my reply carefully.

You need to remove #include "Class3.h" from Class1.h and #include "Class2.h" from Class3.h.

-Saurabh

您具有循环依赖性.您可以使用前向声明将其删除.但是，对于前向依赖项，只允许头文件中的类指针.

You have cyclic dependencies. You can use forward declaration to remove them. However, with forward dependencies you are allowed only class pointers in the header file.

//Class1.h
class Class3; // Forward declaration.
class Class1
{
   ...
   
private:
   
   Class3* mClass3;
};

<br />

//Class2.h
#include "Class1.h" // Cannot use forward declaration because of inheritance.
class Class2 : public Class1 { ... };

<br />

//Class3.h
class Class2;  // Forward declaration.
class Class3
{
   ...
   
private:
   
   Class2* mClass2;
};

-Saurabh

-Saurabh

我尝试了

//Class1.h
#include "Class3.h"
class Class3;
class Class1 { ... };

//Class2.h
#include "Class1.h" // error C2504: ''Class1'' : base class undefined
class Class2 : public Class1 { ... };

//Class3.h
#include "Class2.h"
class Class2;
class Class3 { ... };

但这是行不通的.如上所示的错误C2504

but it doesn''t work. Error C2504 as shown above

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