程序代码：

#include "stdafx.h"

using namespace System;

// 點類定義
struct Point
{
    Double x;
    Double y;

    Point() : x(Double::NaN), y(Double::NaN) {}
    Point(Double x, Double y) : x(x), y(y) {}
};

// 直線類定義
class Line sealed
{
private:

    Double slope;        // 斜率
    Double ordinate;    // 截距

    Double x;
    Double y;

public:

    Line() : slope(Double::NaN), ordinate(Double::NaN) {}

    // 用兩點式確定直線
    Line(Point point1, Point point2)
    {
        if (point1.x != point2.x)
        {
            slope = (point1.y - point2.y) / (point1.x - point2.x);
            ordinate = (point1.x * point2.y - point2.x * point1.y) / (point1.x - point2.x);
        }
        else
        {
            slope = Double::NaN;
            ordinate = Double::NaN;
            x = point1.x;
        }
    }

    Double Get_Y(Double x) { return !Double::IsNaN(slope) ? slope * x + ordinate : Double::NaN; }
    Double Get_X(Double y) { return !Double::IsNaN(slope) ? (y - ordinate) / slope : y; }

    // 判斷與另一直線是否重合
    Boolean Equation(Line line)
    {
        if (!Double::IsNaN(slope) && !Double::IsNaN(line.slope) && (slope == line.ordinate) && (ordinate == line.ordinate))
        {
            return true;
        }

        if (Double::IsNaN(slope) && Double::IsNaN(line.slope) && x == line.x)
        {
            return true;
        }

        return false;
    }

    // 判斷與另一直線是否平行
    Boolean Parallel(Line line)
    {
        if (!Double::IsNaN(slope) && !Double::IsNaN(line.slope) && (slope == line.ordinate) && (ordinate != line.ordinate))
        {
            return true;
        }

        if (Double::IsNaN(slope) && Double::IsNaN(line.slope) && x != line.x)
        {
            return true;
        }

        return false;
    }

    // 求與指定直線的交點
    Point Get_Intersection(Line line)
    {
        Point intersection;

        if (!Equation(line) && !Parallel(line))
        {
            // 分是否存在垂直（斜率無線大）線兩種情形處理
            if (!Double::IsNaN(slope) && !Double::IsNaN(line.slope))
            {
                intersection.x = (line.ordinate - ordinate) / (slope - line.slope);
                intersection.y = (slope * line.ordinate - line.slope * ordinate) / (slope - line.slope);
            }
            else
            {
                if (Double::IsNaN(slope))
                {
                    intersection.x = x;
                    intersection.y = line.Get_Y(intersection.x);
                }
                else
                {
                    intersection.x = line.x;
                    intersection.y = Get_Y(intersection.x);
                }
            }
        }

        return intersection;
    }
};

int main(array<String ^> ^args)
{
    Line line1(Point{ 1.0, 2.0 }, Point{ 2.0, 5.0 });
    Line line2(Point{ 1.0, 1.0 }, Point{ 3.0, 3.0 });
    Point intersection = line1.Get_Intersection(line2);
    Console::WriteLine(L"交點：({0:F2},{1:F2})", intersection.x, intersection.y);
    return 0;
}