设计并实现二维坐标系下的点的类Point，类的每个对象含有横、纵坐标。为类Point添加必要的计算函数，例如，计算给定点到（0,0）的距离，计算给定点两点间的距离，判断给定点的三个点是否能构成一个三角形等。

代码：

/*
* 04737 c++ 自学考试2019版 第二章课后练习
* 程序设计题 2
* 需求:设计并实现二维坐标系下点的类Point....
*/
#include <iostream>
#include <string>
#include <cmath>
using namespace std;
class Point {
public:
    Point();
    Point(double, double);
    void setPoint(double, double);
    double getDistance();
    double getDistance(Point);
    void printPoint();
private:
    double x, y;
};
Point::Point() {
    x = 0, y = 0;
}
Point::Point(double x0, double y0) {
    x = x0, y = y0;
}
void Point::setPoint(double x0, double y0) {
    x = y0, y = y0;
    return;
}
void Point::printPoint() {
    cout << "(" << x << "," << y << ")" << endl;
    return;

}
double Point::getDistance() {
    return sqrt(x * x + y * y);
}
//求两点之间的距离
double Point::getDistance(Point p) {
    return sqrt(pow(abs(x - p.x), 2) + pow(abs(y - p.y), 2));
    //公式是勾股定理 sqrt()函数求开根号， pow(a,b)函数是a的b次方例如：pow(3,2)是3的平方~
}

bool isTriangle(double a, double b, double c) {
    //三角形的组成条件为： 任意一边小于其他两边之和
    if ((a < b + c) && (b < a + c) && (c < a + b)) {
        return true;
    }
    return false;
}
int main()
{
    Point p(0, 0), p1(1, 2), p2(3, 4), p3(4, 6);
    cout << "有4个点:" << endl;
    cout << "p:";
    p.printPoint();
    cout << "p1:";
    p1.printPoint();
    cout << "p2:";
    p2.printPoint();
    cout << "p3:";
    p3.printPoint();
    
    // 给定点到原点的距离
    cout << endl;
    double d1 = p1.getDistance();
    double d2 = p2.getDistance();
    double d3 = p3.getDistance();
    
    cout << "点p1到原点p的距离:" << d1 << endl;
    cout << "点p2到原点p的距离:" << d2 << endl;
    cout << "点p3到原点p的距离:" << d3 << endl;
    
    // 给定两点间的距离
    cout << endl;
    double a = p1.getDistance(p2);
    double b = p1.getDistance(p3);
    double c = p2.getDistance(p3);
    
    cout << "点p1到p2的距离:" << a << endl;
    cout << "点p1到p3的距离:" << b << endl;
    cout << "点p2到p3的距离:" << c << endl;

    // 判断给定3个点能够构成三角形
    cout << endl;
    bool it = isTriangle(a, b, c);

    if (it) {
        cout << "点p1,p2,p3可以构成三角形";
    }
    else {
        cout << "点p1,p2,p3不可以构成三角形";
    }

    cout << endl;
    return 0;
}

运行结果：