C++ Primer（第5版） 练习 7.27

练习 7.27 给你自己的Screen类添加move、set和display函数，通过执行下面的代码检验你的类是否正确。

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

环境：Linux Ubuntu（云服务器）

工具：vim

代码块

/*************************************************************************
	> File Name: ex7.27.cpp
	> Author: 
	> Mail: 
	> Created Time: Thu 15 Feb 2024 09:18:54 PM CST
 ************************************************************************/

#include<iostream>
using namespace std;

class Screen{
    public:
    using pos = string::size_type;
    
    Screen() = default;
    Screen(pos ht, pos wd): height(ht), width(wd), contents(20, ' ') {}
    Screen(pos ht, pos wd, char c): height(ht), width(wd), contents(ht * wd, c) {}
    
    char get() const;
    char get(pos ht, pos wd) const;
    Screen &move(pos r, pos c);
    Screen &set(char c);
    Screen &set(pos ht, pos wd, char c);
    Screen &display(ostream &output);
    const Screen &display(ostream &output) const;

    private:
    void do_display(ostream &output) const { output<<contents; }

    pos cursor = 0;
    pos height = 0;
    pos width = 0;
    string contents;
};

inline char Screen::get() const{
    return contents[cursor];
}

inline char Screen::get(pos ht, pos wd) const{
    pos row = ht * width;
    return contents[row + wd];
}

inline Screen &Screen::move(pos r, pos c){
    pos row = r * width;
    cursor = row = c;
    return *this;
}

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

inline Screen &Screen::set(pos ht, pos wd, char c){
    contents[ht * width + wd] = c;
    return *this;
}

inline Screen &Screen::display(ostream &output){
    do_display(output);
    return *this;
}

inline const Screen &Screen::display(ostream &output) const{
    do_display(output);
    return *this;
}

int main(){
    Screen myScreen(5, 5, 'X');
    myScreen.move(4, 0).set('#').display(cout);
    cout<<"\n";
    myScreen.display(cout);
    cout<<"\n";

    return 0;
}

运行结果显示如下