问答题 【说明】Point是平面坐标系上的点类，Line是从Point派生出来的直线类。
#include ＜iostream.h＞
class Point
public:
Point (int x, int y) ;
Point (Point &p) ;
～Point();
void set (double x, double y) ;
void print();
private:double X,Y;
;
Point::Point (int x, int y) //Point 构造函数
X=x; Y=y;
Point::Point ( (1) ) //Point 拷贝构造函数
X=p.X; Y=p.Y；
void Point::set (double x, double y)
X=x; Y=y;
void Point::print()
cout＜＜' ('＜＜X＜＜","＜＜Y＜＜") "＜＜endl;
Point::～Point()
cout＜＜"Point 的析构函数被调用! "＜＜endl;
class Line: public Point
public:
Line (int x, int y, int k) ;
Line (Line &s) ;
～Line();
void set (double x, double y, double k)
void print();
private:double K;
;
(2) //Line 构造函数实现
K=k;
(3) //Line 拷贝构造函数实现
K=s.K;
void Line::set (double x, double y, double k)
(4) ;
K=k;

void Line::print()
cout＜＜" 直线经过点";
(5) ;
cout＜＜"斜率为: k="＜＜K＜＜endl;

Line: :～Line()
cout＜＜"Line 析构函数被调用! "＜＜endl;

void main()
Line 11 (1,1,2) ;
11 .print();
Linel2 (11) ;
12.set (3,2,1) ;
12.print();