在C++中，我希望兩個類互相訪問

Question

我有兩個班，class A和class B。

A.h -> A.cpp 
B.h -> B.cpp 

然後，我集B爲A類成員之後，A類可以通過

#include <B.h> 

訪問B類但是，我怎麼能得到A類的指針B類並訪問A類公共成員？

我在互聯網上發現了一些信息：一個跨班級。他們說你可以通過設置B類爲A類

你有任何其他建議嵌套類做的？

對不起。 mycode的：爲遵循..

class A: 

#ifndef A 
#define A 

#include "B.h" 

class A 
{ 
public: 
    A() { 
     b = new B(this); 
    } 

private: 
    B* b; 
}; 

#endif 


#ifndef B 
#define B 

#include"A.h" 

class B 
{ 
public: 
    B(A* parent = 0) { 
     this->parent = parent; 
    } 

private: 
    A* parent; 
}; 

#endif 

Answer 1

只需使用forward declaration。像：

A.H：

#ifndef A_h 
#define A_h 

class B; // B forward-declaration 

class A // A definition 
{ 
public: 
    B * pb; // legal, we don't need B's definition to declare a pointer to B 
    B b; // illegal! B is an incomplete type here 
    void method(); 
}; 

#endif 

B.h：

#ifndef B_h 
#define B_h 

#include "A.h" // including definition of A 

class B // definition of B 
{ 
public: 
    A * pa; // legal, pointer is always a pointer 
    A a; // legal too, since we've included A's *definition* already 
    void method(); 
}; 

#endif 

A.cpp

#inlude "A.h" 
#incude "B.h" 

A::method() 
{ 
    pb->method(); // we've included the definition of B already, 
        // and now we can access its members via the pointer. 
} 

B.cpp

#inlude "A.h" 
#incude "B.h" 

B::method() 
{ 
    pa->method(); // we've included the definition of A already 
    a.method(); // ...or like this, if we want B to own an instance of A, 
        // rather than just refer to it by a pointer. 
} 

知道B is a class足以讓編譯器定義pointer to B，無論B是什麼。當然，.cpp文件應包括A.h和B.h以便能夠訪問類成員。