Dunk

        /// <summary>
        /// Exports the datagrid to CSV.
        /// </summary>
        /// <param name="dataGridView1">The data grid view1.</param>
        /// <param name="FileName">Name of the file.</param>
        /// <param name="ColumnName">Name of the column.</param>
        /// <param name="HasColumnName">if set to <c>true</c> [has column name].</param>
        public static void ExportDatagridToCsv(DataGridView dataGridView1 , string FileName ,string[] ColumnName,bool HasColumnName)
        {            
            string strValue = string.Empty;
            //CSV 匯出的標題 要先塞一樣的格式字串 充當標題
            if(HasColumnName == true)            
                strValue = string.Join(",", ColumnName);            
            for (int i = 0; i < dataGridView1.Rows.Count-1; i++)
            {
                for (int j = 0; j < dataGridView1.Rows[i].Cells.Count; j++)
                {
                    if (!string.IsNullOrEmpty(dataGridView1[j, i].Value.ToString()))
                    {
                        if (j > 0)
                            strValue = strValue + "," + dataGridView1[j, i].Value.ToString();
                        else
                        {
                            if (string.IsNullOrEmpty(strValue))
                                strValue = dataGridView1[j, i].Value.ToString();
                            else
                                strValue = strValue + Environment.NewLine + dataGridView1[j, i].Value.ToString();
                        }
                    }
                    else
                    {
                        if (j > 0)
                            strValue = strValue + ",";
                        else                        
                            strValue = strValue + Environment.NewLine;                        
                    }
                }

            }
            //存成檔案
            string strFile = FileName;
            if (!string.IsNullOrEmpty(strValue))
            {
                File.WriteAllText(strFile, strValue, Encoding.Default);
            }
        }
        /// <summary>
        /// Exports the data table to CSV.
        /// </summary>
        /// <param name="dt">The dt.</param>
        /// <param name="FileName">Name of the file.</param>
        /// <param name="ColumnName">Name of the column.</param>
        /// <param name="HasColumnName">if set to <c>true</c> [has column name].</param>
        public static void ExportDataTableToCsv(DataTable dt, string FileName, string[] ColumnName,bool HasColumnName)
        {
            string strValue = string.Empty;
            //CSV 匯出的標題 要先塞一樣的格式字串 充當標題
            if(HasColumnName == true)
                strValue = string.Join(",", ColumnName);
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    if (!string.IsNullOrEmpty(dt.Rows[i][j].ToString()))
                    {
                        if (j > 0)
                            strValue = strValue + "," + dt.Rows[i][j].ToString();
                        else
                        {
                            if (string.IsNullOrEmpty(strValue))
                                strValue = dt.Rows[i][j].ToString();
                            else
                                strValue = strValue + Environment.NewLine + dt.Rows[i][j].ToString();
                        }
                    }
                    else
                    {
                        if (j > 0)
                            strValue = strValue + ",";
                        else
                            strValue = strValue + Environment.NewLine;
                    }
                }

            }
            //存成檔案
            string strFile = FileName;
            if (!string.IsNullOrEmpty(strValue))
            {
                File.WriteAllText(strFile, strValue, Encoding.Default);
            }
        }
        /// <summary>
        /// Reads the CSV to list.
        /// </summary>
        /// <param name="FileName">Name of the file.</param>
        /// <returns></returns>
        public static List<string> ReadCsvToList(string FileName)
        {
            FileInfo fi = new FileInfo(FileName);
            if(fi.Exists)
            {
                List<string> result = new List<string>();
                using(StreamReader sr = new StreamReader(FileName))
                {
                    while (sr.Peek() >= 0)
                    {
                        result.Add(sr.ReadLine());
                    }

                }
                return result;
            }
            else return null;
        }
        /// <summary>
        /// Reads the CSV to data table.
        /// </summary>
        /// <param name="FileName">Name of the file.</param>
        /// <param name="HasColumnName">if set to <c>true</c> [has column name].</param>
        /// <returns></returns>
        public static DataTable ReadCsvToDataTable(string FileName, bool HasColumnName)
        {
            List<string> Input = ReadCsvToList(FileName);
            if(Input != null)
            {
                string[] sep = new string[]{","};
                DataTable dt = new DataTable();
                int StartCount = (HasColumnName == true) ? 1:0;
                string[] ColumnName = Input[0].Split(sep,StringSplitOptions.None);
                for (int i = 0; i < ColumnName.Length; i++)
                    dt.Columns.Add((HasColumnName == true) ? ColumnName[i] : "C" + i.ToString(), typeof(string));
                for(int j= StartCount; j<Input.Count; j++)
                {
                    string[] valuetemp = Input[j].Split(sep,StringSplitOptions.None);
                    dt.Rows.Add(valuetemp);
                }
                return dt;
            }
            else return null;
        }
        #endregion