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7.23 screen.cpp
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7.23 screen.cpp
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#include <iostream>
#include <string>
using namespace std;
class Screen {
public:
typedef std::string::size_type pos;
// default function
Screen() = default;
Screen(pos ht, pos wd) : height(ht), width(wd), contents(ht * wd, ' ') { }
Screen(pos ht, pos wd, char c) : height(ht), width(wd), contents(ht * wd, c) { }
private:
// initial variable
pos cursor = 0;
pos width = 0;
pos height = 0;
string contents;
public:
Screen &set(char);
Screen &set(pos, pos, char);
Screen &move(pos, pos);
// decided by const how to display
Screen &display(std::ostream &os) { do_display(os); return *this; } // no const
const Screen &display(std::ostream &os) const { do_display(os); return *this; } //const
private:
void do_display(std::ostream &os) const { os << contents; } // subfunction
};
inline Screen &Screen::set(char c) {
contents[cursor] = c;
return *this;
}
inline Screen &Screen::set(pos r, pos c, char ch) {
contents[r * width + c] = ch;
return *this;
}
inline Screen &Screen::move(pos r, pos c) {
pos row = r * width;
cursor = row + c;
return *this;
}
int main() {
Screen myScreen(5, 5, 'X');
myScreen.move(4, 0).set('#').display(cout);
cout << endl;
myScreen.display(cout);
cout << endl;
return 0;
}