模板类的友元重载

c++代码实现模板类的友元重载

#include <iostream>using namespace std;template <class T>class Test;template <class T>ostream& operator<<(ostream& out, const Test<T> &obj);template <class T>class Test{    private:        int num;    public:        Test(int n = 0){            num = n;        }        Test(const Test<T> &copy)        {            num = copy.num;        }        friend ostream& operator<< <T> (ostream& out, const Test<T> &obj);}; template <class T>ostream & operator<< (ostream &out, const Test<T> &obj){    out << obj.num;    return out;}int main(){    Test<int> t(2);    cout << t;    return 0; }