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

template<class T1,class T2>
class Car;

//全局函数不用作用域
template<class T1,class T2>
void printCar2(Car<T1,T2> p)
{
    cout << "类外实现：name = " << p.c_name << " age = " << p.c_age << endl;
}
template<class T1,class T2>
class Car
{
    //全局函数类内实现
    friend void printCar(Car<T1,T2> p)
    {
        cout << "类内实现：name = " << p.c_name << " age = " << p.c_age << endl;
     }

     // 全局函数类外实现  ：
     // 加一个空模板的参数列表<>
     // 如果全局函数类外实现，需要让编译器提前知道这个函数存在
     friend void printCar2<>(Car<T1,T2> p);

public:
    Car(T1 name,T2 age)
    {
        this->c_age = age;
        this->c_name = name;
    }
    T1 c_name;
    T2 c_age;
};


void test_16()
{
    Car<string,int> c("tom",3);
    printCar(c);
    printCar2(c);
}






int main()
{
    test_16();
}