关于友元函数的编译没通过，求帮助！！

#include <iostream>
#include "string"
using namespace std;
class Screen;
class Cursor
{
     typedef string::size_type index;
     void relocate(index, index, Screen& C)
     {cout << C.name << endl;}
private:
};
class Screen
{
     friend void Cursor::relocate(Cursor::index, Cursor::index, Cursor::Screen& C);
     Screen(string &b):name(b){}
private:
     string name;
};
int main()
{
     Cursor A;
     Screen B("HAHA");
     A.relocate(1,1,B);
     system("PAUSE");
     return 0;
}
error C2027: use of undefined type 'Screen'
error C2228: left of '.name' must have class/struct/union type
error C2039: 'Screen' : is not a member of 'Cursor'
error C2664: '__thiscall Screen::Screen(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &)' : cannot convert parameter 1 from 'char [5]'
to 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &'
error C2248: 'relocate' : cannot access private member declared in class 'Cursor'
可能是涉及哪个类先定义，哪个先声明的问题，~~迷惘，求解释

求改正

吧定义与声明分开写

不感兴趣

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是实现和定义……

能详细点么。。不太清楚
void relocate(index, index, Screen& C)
{cout << C.name << endl;}
这个么？还是什么

把relocate 写到Screen类后面，
void Cursor::relocate(index, index, Screen& C)
{ {cout << C.name << endl;}}
有个错误是没了，但其他错误没解决。。肿么改啊

#include <iostream>#include <string>using namespace std;class Screen;class Screen{public: Screen(string &b):name(b){}//构造竟然私有 friend class Cursor;private: string name;};class Cursor{public: typedef string::size_type index; void relocate(index, index, Screen& C) {cout << C.name << endl;}private: };
int main(){ Cursor A; Screen B(string("HAHA"));//汗~~ A.relocate(1,1,B); system("PAUSE"); return 0;}

错误百出了。。但是还是没指出关重点。。重新更正下：
#include <iostream>
#include "string"
using namespace std;
class Screen;//不是有前声明Screen么
class Cursor
{
public:
     typedef string::size_type index;
     void relocate(index, index, Screen& C);//主要这里的Screen
};
class Screen
{
public:
     friend void Cursor::relocate(Cursor::index, Cursor::index, Cursor::Screen& C);    //error C2039: 'Screen' : is not a member of 'Cursor'
     Screen(const string &b):name(b){}
private:
     string name;
};
void Cursor::relocate(index, index, Screen& C)
{
      {cout << C.name << endl;}
}
int main()
{
     Cursor A;
     Screen B("HAHA");
     A.relocate(1,1,B);
     system("PAUSE");
     return 0;
}
更正成这样，但还编译不过！