题目为计算两点之间距离。

面向过程的思维方式，两点的横坐标之差，纵坐标之差，平方求和，再开跟，得到两点之间距离。

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace Classes_2_point_distance{    class Program    {        static void Main(string[] args)        {            int x1 = -1;            int y1 = -1;            int x2 = int.Parse(Console.ReadLine());            int y2 = int.Parse(Console.ReadLine());            int xdiff = x2 - x1;            int ydiff = y2 - y1;            double distance = Math.Sqrt(xdiff * xdiff + ydiff * ydiff);            Console.WriteLine(distance);            Console.ReadKey();        }    }}

　　面向对象的思路，题目中，两点间直线距离，名词包括点、直线、距离,首先我们构造一个点类。

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace Classes_2_point_distance{    class Point    {        private int x;        private int y;        public Point()        {            x = -1;            y = -1;        }        public Point(int h, int z)        {            x = h;            y = z;        }        public double Distance(Point p)        {            int xdiff = x - p.x;            int ydiff = y - p.y;            return Math.Sqrt(xdiff * xdiff + ydiff * ydiff);                    }    }}

　　

然后再Programe.cs中实例化p1，p2两个点，计算距离

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace Classes_2_point_distance{    class Program    {        static void Main(string[] args)        {            //int x1 = -1;            //int y1 = -1;            int x2 = int.Parse(Console.ReadLine());            int y2 = int.Parse(Console.ReadLine());            //int xdiff = x2 - x1;            //int ydiff = y2 - y1;            //double distance = Math.Sqrt(xdiff * xdiff + ydiff * ydiff);            //Console.WriteLine(distance);            //Console.ReadKey();            Point p1 = new Point();            Point p2 = new Point(x2, y2);            double distance = p1.Distance(p2);            Console.WriteLine(distance);            Console.ReadKey();        }    }}