5月22日打卡

例具有静态数据、成员函数的Point类

代码部分：

#include<iostream>
using namespace std;
class Point {
private:
    int x, y;
    static int count;
public:
    Point(int x=0,int y=0):x(x),y(y)
    {
        count++;
    }
    Point(Point& p)
    {
        x = p.x;
        y = p.y;
        count++;
    }
    ~Point() { count--; }
    int getX() { return x; }
    int getY() { return y; }
    static void showCount() {
        cout << "Object count=" << count << endl;
    }
};
int Point::count = 0;
int main()
{
    Point a(4, 5);
    cout << "Point a:" << a.getX() << "," << a.getY();
    Point::showCount();
    Point b(a);
    cout << "Point B:" << b.getX() << "," << b.getY();
    Point::showCount();
    return 0;
}

例5-6

题目描述：

使用友元函数计算两点间的距离。

代码部分：

#include<iostream>
#include<cmath>
using namespace std;
class Point {
private:
    int x, y;
public:
    Point(int x = 0, int y = 0) :x(x), y(y) {};
    int getX() { return x; }
    int getY() { return y; }
    friend float dist(Point& p1, Point& p2)
    {
        double x = p1.x - p2.x;
        double y = p1.y - p2.y;
        return static_cast<float>(sqrt(x * x + y * y);
    }
};
int main()
{
    Point myp1(1, 1), myp2(4, 5);
    cout << "The distance is:";
    cout << dist(myp1, myp2) << endl;
    return 0;
}