一个类的友元类能访问类的私有数据

// test.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

class CAnimal
{
public :
int m_sex;
public:
void SetSex(int sex)
{
m_sex = sex;
}
//******************************
//定义友元函数
friend int GetSex(CAnimal& am);

///********************************
//声明友类
friend class CCat;
};

int GetSex(CAnimal& am)
{
return am.m_sex ;
}

class CCat
{
public:
int GetSex(CAnimal& am)
{
return am.m_sex ;
}
};

int main(int argc, char* argv[])
{
CAnimal animal;
CCat kitty;
animal.m_sex = 'M';

int sex =kitty.GetSex(animal);
return 0;
}