59.模板和友元

类内实现

main.cpp

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include <string>
using namespace std;

template<class T1, class T2>
class Person
{
	//友元函数类内实现
	friend void printPerson(Person<T1, T2> & p)
	{
		cout << "姓名：" << p.m_Name << "  年龄： " << p.m_Age << endl;
	}
public:
	Person(T1 name, T2 age)
	{
		this->m_Name = name;
		this->m_Age = age;
	}

private:
	T1 m_Name;
	T2 m_Age;
};

void test01()
{
	Person<string, int> p("Tom", 10);
	printPerson(p);//输出：姓名：Tom  年龄： 10
}


int main(){
	test01();


	system("pause");
	return EXIT_SUCCESS;
}

类外实现

main.cpp

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include <string>
using namespace std;

//让编译器提前看到printPerson声明

//让编译器看到Person类声明
template<class T1, class T2> class Person;//Person类的声明
template<class T1, class T2>void printPerson(Person<T1, T2> & p);


template<class T1, class T2>
class Person
{
	//友元函数类内实现  利用空参数列表 告诉编译器 模板函数的声明
	friend void printPerson<>(Person<T1, T2> & p); //普通函数 声明
	/*{
	cout << "姓名：" << p.m_Name << "  年龄： " << p.m_Age << endl;
	}*/
public:
	Person(T1 name, T2 age)
	{
		this->m_Name = name;
		this->m_Age = age;
	}

private:
	T1 m_Name;
	T2 m_Age;
};

//类外实现
template<class T1, class T2>
void printPerson(Person<T1, T2> & p)
{
	cout << "姓名：" << p.m_Name << "  年龄： " << p.m_Age << endl;
}

void test01()
{
	Person<string, int> p("Tom", 10);
	printPerson(p);//输出：姓名：Tom  年龄： 10
}


int main(){

	test01();

	system("pause");
	return EXIT_SUCCESS;
}