C++基础学习(四)，友元函数和友元类

#include <iostream>
#include <string>

using namespace std;

//使用friend关键字让外部函数DisplayAge()能够访问私有数据成员
class Humen
{
public:
	Humen(string name, int age)
		:m_strName(name), m_nAge(age)
	{

	}

private:
	string m_strName;
	int m_nAge;
	friend void DisplayAge(const Humen& person);
};

void DisplayAge(const Humen& person)
{
	cout<<"age : "<<person.m_nAge<<endl;
}

int main()
{
	Humen person("xxx", 11);
	DisplayAge(person);
	system("pause");
	return 0;
}

#include <iostream>
#include <string>

using namespace std;

//使用friend关键字让外部类Utility能够访问私有数据成员
class Humen
{
public:
	Humen(string name, int age)
		:m_strName(name), m_nAge(age)
	{

	}

private:
	string m_strName;
	int m_nAge;
	friend class Utility;
};

class Utility
{
public:
	static void DisplayAge(const Humen& person)
	{
		cout<<"age : "<<person.m_nAge<<endl;
	}
};

int main()
{
	Humen person("xxx", 11);
	Utility::DisplayAge(person);
	system("pause");
	return 0;
}