自考新教材-p90_5(3)

源程序：

#include <iostream>
#include <math.h>
using namespace std;
class Point
{
private:
float x, y;
public:
Point(float a, float b);
float getX();
float getY();
void print();
};
Point::Point(float a, float b)
{
x = a;
y = b;
}
float Point::getX()
{
return x;
}
float Point::getY()
{
return y;
}
void Point::print()
{
cout << "(" << "," << y << ")" << endl;
}
class Line
{
private:
Point p1, p2;
public:
Line(Point &, Point &);
friend float distance(Line &p, Point &q);

double xielv()
{
return abs((p1.getY() - p2.getY())) / abs((p1.getX() - p2.getX()));
}
};
Line::Line(Point &_p1, Point &_p2) :p1(_p1), p2(_p2)
{
//p1 = _p1;
//p2 = _p2;
}

float distance(Line &p, Point &q)
{
float x1 = p.p1.getX();
float y1 = p.p1.getY();
float x2 = p.p2.getX();
float y2 = p.p2.getY();
float x = q.getX();
float y = q.getY();
return ((x - x1)*(y2 - y1) - (x2 - x1)*(y - y1)) / sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
}
int main()
{
Point p1(2, 5);
Point p2(7, 9);
Point p(0, 0);
Line L(p1, p2);
cout << "直线的斜率为："<<L.xielv() << endl;
cout << "点p到直线的距离为："<<distance(L, p) << endl;
system("pause");
return 1;
}

运行结果：