是否可以访问班级的私人成员？

Is it possible to access private members of a class in c++.

是否可以在c ++中访问类的私有成员。

provided you don't have a friend function and You don't have access to the class definition

如果您没有朋友功能,并且您无权访问类定义

4 个解决方案

#1

You mean using some pointer arithmetic to gain the access ? It is possible but is definitely dangerous. Take a look at this question also: Accessing private members

你的意思是使用一些指针算法来获得访问权限?这是可能的,但绝对是危险的。另请看一下这个问题:访问私人会员

#2

I think there was some old school trick like this:

我觉得有一些像这样的旧学校伎俩:

#define private public
#include "header.h"
#define private private

But you are strongly discouraged to do this (I've read quickly that the said something about this in the C++ standard) - if you want to read more about this google for "#define private public"

但是你强烈反对这样做(我很快就读到了C ++标准中关于这一点的说法) - 如果你想阅读更多关于谷歌的信息“#define private public”

#3

Well I might be talking rubish, but I think you could try to define a "twin" class with same members as the class you want to modify but different public/private modifiers and then use reintepret_cast to cast the original class to yours in which you can access the private members.

好吧,我可能会说rubish,但我认为你可以尝试定义一个“twin”类,其中包含与要修改的类相同的成员,但是使用不同的公共/私有修饰符,然后使用reintepret_cast将原始类转换为您的类可以访问私人会员。

Its a bit hacky ;-)

它有点hacky ;-)

A bit of code to explain the idea:

一些代码来解释这个想法:

class ClassWithNoAccess 
{
public:
  someMethod();

private:
  int someVar;
};

class ClassTwin 
{
public:
  someMethod();

public:
  int someVar;
}

and somewhere in the code:

在代码中的某个地方:

ClassWithNoAccess* noAccess = new ClassWithNoAccess();
ClassTwin* twin = reinterpret_cast<ClassTwin *>(noAccess);
twin->someVar = 1;

edit: so like someone already wrote before, this might work but the standard does not guarantee the order of the variables with public and private modifier will be the same

编辑:所以像之前已经写过的人一样,这可能会有效,但是标准并不能保证变量的顺序与public和private修饰符一样

#4

Even if it were possible through some nasty hack - see earlier posts - you SHOULD not do it.

即使有可能通过一些讨厌的黑客 - 见前面的帖子 - 你也不应该这样做。

Encapsulation exists for a very good purpose, and setting class member as private means that the developer did not intend anyone to mess around with that member. That should mean

封装存在是为了一个非常好的目的,并且将类成员设置为私有意味着开发人员不打算任何人乱搞该成员。那应该意味着

"You don't have to access this member in order to use the public interface to it's full intended extent"

“您不必访问此成员,以便将公共接口用于其完整的预期范围”

#1