头文件
*****************************************************************8
#ifndef TOUTOU_H
#define TOUTOU_H

#include<iostream>
#include<string>
using namespace std;
using std::iostream;
using std::string;
using std::cout;
class Screen {
public:
    using pos = std::string::size_type;

    Screen() = default;
    Screen(pos ht, pos wd) :height(ht), width(wd), conents(ht*wd, ' ') {}
    Screen(pos ht, pos wd, char c) :height(ht), width(wd), conents(ht*wd, c) {}

    char get() const { return conents[cursor]; }                                         ***********   cursor未定义
    char get(pos r, pos s)  const { return conents[r*width + s]; }
    Screen &move(pos r, pos s);
    Screen &set(char c);
    Screen &set(pos r, pos s, char c);

    const Screen &display(std::ostream &os) const { do_display(os); return *this; }
    Screen &display(std::ostream &os) { do_display(os); return *this; }

private:
    void do_display const (ostream &os) {
        os << conents;
    }
private:
    pos cursor = 0;
    pos height = 0;
    std::string conents;
    pos width = 0;
};
inline Screen& Screen::move(pos r, pos s) {
    cursor = r*width + s;
    return *this;
}

inline Screen& Screen::set(char c) {
    conents[cursor] = c;
    return *this;
}

inline Screen& Screen::set(pos r, pos s, char c) {
    conents[r*width + s] = c;
    return *this;
}
#endif
 
程序
**********************************************************************
#include"C:\Users\Jin\Desktop\toutou.h"
int main()
{
   

   
    Screen myScreen(5,5,'X');                            ******************* Screen未定义
    myScreen.move(4, 0).set('#').display(cout);          ******************* cout未定义
     cout << "\n";
    myScreen.display(cout);
    cout << "\n";

    return 0;
}

是一个题在github上的答案，不知原来的代码为啥不对呢