C#小白在线乞求大佬解释一下这一整段代码，这段代码对我非常重要，希望有大佬能帮我解析一下

Question

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 索引器的使用
{
    class Program
    {
        private double[,] elements;
        private int row = 1;
        private int col = 1;
        public int Row
        {
            get
            {
                return row;
            }
        }
        public int Col
        {
            get
            {
                return col;
            }
        }
        public double[] this[int r]
        {
            get
            {
                if(r>=row||r<0)
                {
                    throw new IndexOutOfRangeException();
                }
                double[] vector = new double[col];
                for(int i=0;i<col;i++)
                {
                    vector[i] = elements[r, i];
                }
                return vector;
            }
            set
            {
                if(r>=row||r<0)
                {
                    throw new IndexOutOfRangeException();
                }
                for(int i=0;i<col;i++)
                {
                    elements[r, i] = value[i];
                }
            }
            
        }
        public double this[int r,int c]
        {
            get
            {
                if(r>=row||r<0||c>=col||c<0)
                {
                    throw new IndexOutOfRangeException();
                }
                return elements[r, c];
            }
            set
            {
                if(r>=row||r<0||c>=col||c<0)
                {
                    throw new IndexOutOfRangeException();
                }
                elements[r, c] = value;
            }
        }
        public void Chuli ()
        {
            row = 1;
            col = 1;
            elements = new double[row, col];
        }
        public void Chuli(int row,int col)
        {
            this.row = row;
            this.col = col;
            elements = new double[row, col];
        }
        static void Main(string[] args)
        {
            const int ROW= 8;
            const int COL = 8;
            Program chuli = new Program();
            chuli.Chuli(ROW, COL);
            for (int i=0;i<chuli.Row;i++)
            {
                for(int j=0;j<chuli.Col;j++)
                {
                    chuli[i, j] = i * j;
                }
            }
            for(int i=0;i<chuli.Row;i++)
            {
                for(int j=0;j<chuli.Col;j++)
                {
                    Console.Write("{0,4}", chuli[i, j]);
                }
                Console.WriteLine();
                Console.ReadKey();
            }
            double[] vector = chuli[4];
            for(int j=0;j<vector.Length;j++)
            {
                Console.Write("{0,4}", vector[j]);
            }
            Console.ReadKey();
        }
    }
}

Answer 1

using System;

namespace 索引器的使用
{
    class Program
    {
        private double[,] elements;                                                 //定义二维数组
        private int row = 1;                                                        //定义行
        private int col = 1;                                                        //列
        public int Row                                                              //get方法获取值:属性
        {                                                                           //同一个类里能访问到row和col，还写了个只读属性（问号脸）
            get
            {
                return row;
            }
        }
        public int Col                                                              //get方法获取值:属性
        {
            get
            {
                return col;
            }
        }
        public double[] this[int r]                                                 //声明返回一维double数组的索引器，索引为r
        {
            get
            {
                if (r >= row || r < 0)                                              //如果索引元素异常，抛出异常
                {
                    throw new IndexOutOfRangeException();
                }
                double[] vector = new double[col];
                for (int i = 0; i < col; i++)
                {
                    vector[i] = elements[r, i];                                     //赋值给vector
                }
                return vector;                                                      //返回vector数组
            }
            set
            {
                if (r >= row || r < 0)                                              //如果索引元素异常，抛出异常
                {                                                                   
                    throw new IndexOutOfRangeException();
                }
                for (int i = 0; i < col; i++)
                {
                    elements[r, i] = value[i];                                     //设置elements[r, i]的值
                }
            }

        }
        public double this[int r, int c]                                          //声明返回值为double的索引器。索引为r，c
        {
            get
            {
                if (r >= row || r < 0 || c >= col || c < 0)                       //如果索引元素异常，抛出异常
                {
                    throw new IndexOutOfRangeException();
                }
                return elements[r, c];                                            //否则返回elements[r, c]元素
            }
            set
            {
                if (r >= row || r < 0 || c >= col || c < 0)
                {
                    throw new IndexOutOfRangeException();
                }
                elements[r, c] = value;                                            //设置elements[r, c]的值
            }
        }
        //public void Chuli()                                                         //没用到可注释掉，其实是测试异常的方法
        //{
        //    row = 1;
        //    col = 1;
        //    elements = new double[row, col];
        //}
        public void Chuli(int row, int col)                                           //函数赋值兼声明数组长度
        {
            this.row = row;
            this.col = col;
            elements = new double[row, col];
        }
        static void Main(string[] args)
        {                                                                             
            const int ROW = 8;                                                        
            const int COL = 8;                                                        
            Program chuli = new Program();                                            //实例化program对象为chuli
            chuli.Chuli(ROW, COL);                                                    //调用Chuli函数
            for (int i = 0; i < chuli.Row; i++)                                       //遍历行
            {                                                                         //
                for (int j = 0; j < chuli.Col; j++)                                   //遍历列
                {                                                                     //
                    chuli[i, j] = i * j;                                              //赋值给数组元素
                }
            }
            for (int i = 0; i < chuli.Row; i++)                                       //遍历行
            {                                                                         //
                for (int j = 0; j < chuli.Col; j++)                                   //遍历列
                {                                                                     //
                    Console.Write("{0,4}", chuli[i, j]);                              //输出数组元素
                }
                Console.WriteLine();
                Console.ReadKey();
            }
            double[] vector = chuli[4];                                               //声明vector一维数组，把chuli第五行元素赋值给vector
            for (int j = 0; j < vector.Length; j++)
            {
                Console.Write("{0,4}", vector[j]);                                    //输出vector元素
            }
            Console.ReadKey();
        }
    }
}

应该就是这样了，本人只是学了一个月左右吧，如果有不对的地方请大佬指出，欢迎批评，题主有不懂的问我我尽量给你解答一下