friend A& operator++(A& a)//前++ { a.data += 10; return a; }我想问的是,前面的friend A& 这个引用有什么意义吗?加和不加有什么区别吗?

friend istream &operator>> friend ostream & operator friend Point operator +(const Point& a,const Point& b); 我是新手,不懂,越详细越好. A.operator+(B) operator 还有请问friend istream& operator >>(istream &,zhui &); 里istream是什么 friend istream&operator>>(istream &in,Point &p) ;friend istream&operator >>(istream &in,Point &p) ; 这里的&符号又是什么意思啊 'operator =' must be a member啥意思#includeclass String{public:String(char *str=NULL);friend void operator=(String&a,String&b);void show();private:char *name;};int main(){return 0;}编译提示：error C2801:'operator =' must be a member friend A& operator++(A& a)//前++ { a.data += 10; return a; }我想问的是,前面的friend A& 这个引用有什么意义吗?加和不加有什么区别吗? She is a keyboard operator变为复数 I'm a keyboard operator.汉语怎莫说? A covert front-line operator.啥意思? C++错误之INTERNAL COMPILER ERROR源代码是：#includeusing namespace std;class complex{ float real,image;public: complex(float r=0,float i=0) {real=r;image=i;} void print(); friend complex operator+(complex a,complex b); friend complex operator- is keyboard operator Tom's father a拼成句子 c++运算符重载为何complex operator+(complex &a,complex &b)也对,complex operator+(complex &a)也对 i am a keyboard operator.i operate keyboard.这么说行吗?看新概念看到的keyboard operator ''operator''是什么意思? operator assist