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问题描述
I am curious about a scenario set up like the following example:
Here is code that would be placed in a file called Header1.h:
#ifndef HEADER1_H
#define HEADER1_H
#include "Header2.h"
class Class1
{
Class2 class2Instance;
};
#endif
Here is code that would be placed in a file called Header2.h:
#ifndef HEADER2_H
#define HEADER2_H
#include "Header1.h"
class Class2
{
Class1 class1Instance;
};
#endif
I get error messages when I do this (because of the includes I assume), but it feels like I would need to do this in order to include each of the objects in the separate classes. Can anyone help me accomplish this, what am I doing wrong?
解决方案
The problem is that the size of Class1 depends on Class2, and vice-versa. Therefore, there's no way to calculate the size for either one. Forward-declare one of the classes, and change one of the attributes to be a pointer or reference:
#ifndef HEADER2_H
#define HEADER2_H
class Class1;
class Class2
{
Class1 *class1Instance;
// or
Class1 &class1Instance;
};
#endif
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