public DataTable this[int minRow, int maxRow, int minCol, int maxCol]
            {
                get
                {
                    //数据有效性验证

                    CheckRowValid(minRow);
                    CheckMaxRowValid(maxRow);
                    CheckColValid(minCol);
                    CheckMaxColValid(maxCol);
                    if (maxRow == -1)
                    {
                        maxRow = RowCount;
                    }
                    if (maxCol == -1)
                    {
                        maxCol = ColCount;
                    }
                    if (maxRow < minRow)
                    {
                        throw new Exception("最大行数不能小于最小行数");
                    }
                    if (maxCol < minCol)
                    {
                        throw new Exception("最大列数不能小于最小列数");
                    }
                   DataTable csvDT = new DataTable();
                    int i;
                    int col;
                    int row;

                    //增加列

                    for (i = minCol; i <= maxCol; i++)
                    {
                        csvDT.Columns.Add(i.ToString());
                    }
                    for (row = minRow; row <= maxRow; row++)
                    {
                        DataRow csvDR = csvDT.NewRow();

                        i = 0;
                        for (col = minCol; col <= maxCol; col++)
                        {
                            csvDR[i] = this[row, col];
                            i++;
                        }
                        csvDT.Rows.Add(csvDR);
                    }

                    return csvDT;
                }
            }


看到读csv文件中有如下写法,看不懂. 我看了 入门到精通也没有这个介绍啊.