c++ - friend ，模板，重载<<

我正在尝试使用友元函数来重载 Point.cpp:11: error: shadows template parm 'class T'Point.cpp:12: error: declaration of 'const Point<T>& T'对于这个文件#include "Point.h"template <class T>Point<T>::Point() : xCoordinate(0), yCoordinate(0){}template <class T>Point<T>::Point(T xCoordinate, T yCoordinate) : xCoordinate(xCoordinate), yCoordinate(yCoordinate){}template <class T>std::ostream &operator<<(std::ostream &out, const Point<T> &T){ std::cout << "(" << T.xCoordinate << ", " << T.yCoordinate << ")"; return out;}我的标题看起来像:#ifndef POINT_H#define POINT_H#include <iostream>template <class T>class Point{public: Point(); Point(T xCoordinate, T yCoordinate); friend std::ostream &operator<<(std::ostream &out, const Point<T> &T);private: T xCoordinate; T yCoordinate;};#endif我的标题也给出了警告:Point.h:12: warning: friend declaration 'std::ostream& operator<<(std::ostream&, const Point<T>&)' declares a non-template function我也不确定为什么。有什么想法吗？谢谢。 最佳答案 模板参数和函数参数都具有相同的名称。将其更改为:template <class T>std::ostream &operator<<(std::ostream &out, const Point<T> &point){ std::cout << "(" << point.xCoordinate << ", " << point.yCoordinate << ")"; return out;}头文件中 friend 函数的声明也应该改变:template <class G>friend std::ostream &operator<<(std::ostream &out, const Point<G> &point);关于c++ - friend ，模板，重载<<，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/2963842/