[英]In C++, I want two classes to access each other
I have two classes, class A
and class B
. 我有两个班级, class A
class B
和class B
。
A.h -> A.cpp
B.h -> B.cpp
And then, I set B as a member in class A. Then, class A can access class B by 然后,我将B设置为A类的成员。然后,A类可以通过以下方式访问B类:
#include <B.h>
But, how can I get the pointer of class A in class B and access the public member of class A? 但是,如何获取B类中A类的指针并访问A类的公共成员?
I found some information about on the internet: a Cross-class. 我在互联网上找到了一些信息:跨班。 They said you can make it by setting the class B as a nested class in class A. 他们说可以通过将B类设置为A类中的嵌套类来实现。
Do you have any other advice? 您还有其他建议吗?
sorry. 抱歉。 myCode: as follow.. myCode:如下。
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
Just use forward declaration . 只需使用前向声明 。 Like: 喜欢:
Ah: 啊:
#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
Bh: Bh:
#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 丙型肝炎
#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 丙型肝炎
#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.
}
Knowing that B is a class
is enough for compiler to define pointer to B
, whatever B
is. 知道B is a class
就足以使编译器定义pointer to B
,无论B
是什么。 Of course, both .cpp
files should include Ah
and Bh
to be able to access class members. 当然,两个.cpp
文件都应包含Ah
和Bh
以便能够访问类成员。
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