【共读Primer】63.[7.3]类的其他特性Page243

class Screen
{
public:typedef std::string::size_type pos; // 类型成员 //using pos &＃61; std::string::size_type; // C&＃43;&＃43;11 风格的类型别名定义&＃xff0c;与上一行效果一致
private:pos cursor &＃61; 0;pos height &＃61; 0, width &＃61; 0;std::string contents;
};

class Screen
{
public:typedef std::string::size_type pos; // 类型成员 //using pos &＃61; std::string::size_type; // C&＃43;&＃43;11 风格的类型别名定义&＃xff0c;与上一行效果一致Screen()&＃61;default; // 因为存在带参构造函数&＃xff0c;如果需要使用无参默认构造函数则需要显示声明Screen(pos ht, pos wd, char c): height(ht), width(wd),contents(ht*wd,c){}char get() const{return contents[cursor];} // 类内定义&＃xff0c;默认为内联函数&＃xff08;隐式内联&＃xff09;inline char get(pos ht, pos wd) const; // 类外定义&＃xff0c;但是具有内联关键字为内联函数&＃xff08;显示内联&＃xff09;Screen &move(pos r, pos c); // 在定义时被设为内联函数
private:pos cursor &＃61; 0;pos height &＃61; 0, width &＃61; 0;std::string contents;
};inline Screen &Screen::move(pos r, pos c) // 在定义时指定为内联
{pos row &＃61; r * width; cursor &＃61; row &＃43; c;return *this; // 返回自身的引用
}char Screen::get(pos r, pos c) const
{pos row &＃61; r * width;return contents[row &＃43; c];
}

class Screen
{
public:typedef std::string::size_type pos; // 类型成员 //using pos &＃61; std::string::size_type; // C&＃43;&＃43;11 风格的类型别名定义&＃xff0c;与上一行效果一致Screen()&＃61;default; // 因为存在带参构造函数&＃xff0c;如果需要使用无参默认构造函数则需要显示声明Screen(pos ht, pos wd, char c): height(ht), width(wd),contents(ht*wd,c){}char get() const{return contents[cursor];} // 类内定义&＃xff0c;默认为内联函数&＃xff08;隐式内联&＃xff09;inline char get(pos ht, pos wd) const; // 类外定义&＃xff0c;但是具有内联关键字为内联函数&＃xff08;显示内联&＃xff09;Screen &move(pos r, pos c); // 在定义时被设为内联函数void some_member() const;
public:Screen &set(char);Screen &set(pos, pos, char);Screen &display(std::ostream &os){do_display(os); return *this;}const Screen &display(std::ostream &os) const {do_display(os); return *this;}
private:void do_display(std::ostream &os) const {os << contents;}
private:pos cursor &＃61; 0;pos height &＃61; 0, width &＃61; 0;std::string contents;mutable size_t access_ctr; // 在const对象中也可以被修改
};void Screen::some_member() const
{&＃43;&＃43;access_ctr; // 用于计数被调用次数
}inline Screen &Screen::move(pos r, pos c) // 在定义时指定为内联
{pos row &＃61; r * width; cursor &＃61; row &＃43; c;return *this; // 返回自身的引用
}char Screen::get(pos r, pos c) const
{pos row &＃61; r * width;return contents[row &＃43; c];
}inline Screen &Screen::set(char c)
{contents[cursor] &＃61; c;return *this;
}inline Screen &Screen::set(pos r, pos col, char ch)
{contents[r * width &＃43; col] &＃61; ch;return *this;
}