Develop Reference

DataGridViewS export to excel sheetS

I want to export all my DataGridViews in one Excell document.
For every DataGridView there shoud be a own sheet in the Excell File.
But with my code i only recive the Error: System.Runtime.InteropServices.COMException: HRESULT: 0x800A03EC"
I think there is something wrong with my parameters.
private void exportToExcellButton_Click(object sender, EventArgs e)
{
SaveFileDialog saveFileD = new SaveFileDialog();
string fileName = truckListBox.SelectedItem.ToString() + "__" + DateTime.Now.ToShortDateString();
saveFileD.InitialDirectory = #"C:/TML/";
saveFileD.FileName = fileName;
if (!Directory.Exists(#"C:/TML/"))
Directory.CreateDirectory(#"C:/TML/");
List<DataGridView> dataGridViews = getAllDataGridViews();
Microsoft.Office.Interop.Excel.Application app;
Microsoft.Office.Interop.Excel.Workbook book;
Microsoft.Office.Interop.Excel.Worksheet sheet;
app = new Excel.Application();
app.Visible = true;
book = app.Workbooks.Add(System.Reflection.Missing.Value);
foreach (var grid in dataGridViews)
{
int count = book.Worksheets.Count;
sheet = (Worksheet)book.Sheets.Add(Type.Missing, book.Worksheets[count], Type.Missing, Type.Missing);
sheet.Name = grid.Name.ToString().Remove(0, 13);
int cMin = 0, rMin = 0;
int c = cMin, r = rMin;
// Set Headers
foreach (DataGridViewColumn column in grid.Columns)
{
//Here appears the Error: System.Runtime.InteropServices.COMException: HRESULT: 0x800A03EC"
sheet.Cells[r, c] = column.HeaderText;
c++;
}
sheet.Range[sheet.Cells[r, cMin], sheet.Cells[r, c]].Font.Bold = true;
sheet.Range[sheet.Cells[r, cMin], sheet.Cells[r, c]].VerticalAlignment = Microsoft.Office.Interop.Excel.XlVAlign.xlVAlignCenter;
// Set Rows
foreach (DataGridViewRow row in grid.Rows)
{
r++;
c = cMin;
// Set Cells
foreach (DataGridViewCell item in row.Cells)
{
sheet.Cells[r, c++] = item.Value;
}
}
}
book.Save();
book.Close();
app.Quit();
}
Spended allready days into it and cant get it work.
Thx for your Help!
EDIT: Fixed one error to get to the new one.

There are a few problems you may have with the posted code. Therefore, I will break them down.
For starters, it appears you are using a SaveFileDialog however I do not see where it is being used. The code sets the InitalDirectory and FileName, but it is never used. This is not that important as a dialog is not really needed, however the way the code is getting the file name is going to have some problems. The line of code…
string fileName = truckListBox.SelectedItem.ToString() + "__" + DateTime.Now.ToShortDateString();
is going to have problems if you try to save the file name because the string returned from DateTime.Now.ToShortDateString() is going to be in a format like “2019\11\26”… Obviously the “\” characters are going to be interpreted as a path (folder) and will most likely fail when the code tries to save the file. Creating a method that returns a string that uses some other character should be easy to fix this.
Next is the fact that Excel files are NOT zero based on their rows and columns. Therefore, setting the initial Excel row column variables (int c = 0, r = 0;) will fail on the first try. These values should be one (1).
Another problem is on the line…
book.Save();
Is most likely going to save the file to the users “Documents” folder using the file name of “Book1.xlsx.” When saving the file you need to supply the complete path and file name which as stated earlier does not appear to be used.
Lastly, anytime you use “COM” objects such as Excel apps, workbooks and worksheets, it is very important for the code to “RELEASE” the com objects your code creates before you exit the program. In the current posted code, it is highly likely that there are lingering “Excel” resources still running. Therefore, to avoid leaking resources, it is important for your code to release the com objects it creates.
In my example below the code to release the resources is in the finally clause of the try/catch/finally statement.
private void button1_Click(object sender, EventArgs e) {
//SaveFileDialog saveFileD = new SaveFileDialog();
//string fileName = truckListBox.SelectedItem.ToString() + "__" + DateTime.Now.ToShortDateString();
string fileName = #"C:\Users\John\Desktop\Grr\TestExcelFile" + "__" + DateTime.Now.Year + "_" + DateTime.Now.Month;
//saveFileD.InitialDirectory = #"C:\Users\John\Desktop\Grr\";
//saveFileD.FileName = fileName;
//if (!Directory.Exists(#"C:/TML/"))
// Directory.CreateDirectory(#"C:/TML/");
//List<DataGridView> dataGridViews = getAllDataGridViews();
List<DataGridView> dataGridViews = getGrids();
Microsoft.Office.Interop.Excel.Application app = null;
Microsoft.Office.Interop.Excel.Workbook book = null;
Microsoft.Office.Interop.Excel.Worksheet sheet = null;
app = new Microsoft.Office.Interop.Excel.Application();
app.Visible = true;
book = app.Workbooks.Add(System.Reflection.Missing.Value);
try {
foreach (var grid in dataGridViews) {
int count = book.Worksheets.Count;
//sheet = (Microsoft.Office.Interop.Excel.Worksheet)book.Sheets.Add(Type.Missing, book.Worksheets[count], Type.Missing, Type.Missing);
sheet = (Microsoft.Office.Interop.Excel.Worksheet)book.Worksheets.Add();
//sheet.Name = grid.Name.ToString().Remove(0, 13);
sheet.Name = grid.Name.ToString();
int cMin = 1, rMin = 1;
int c = cMin, r = rMin;
// Set Headers
foreach (DataGridViewColumn column in grid.Columns) {
//Here appears the Error: System.Runtime.InteropServices.COMException: HRESULT: 0x800A03EC"
sheet.Cells[r, c] = column.HeaderText;
c++;
}
sheet.Range[sheet.Cells[r, cMin], sheet.Cells[r, c]].Font.Bold = true;
sheet.Range[sheet.Cells[r, cMin], sheet.Cells[r, c]].VerticalAlignment = Microsoft.Office.Interop.Excel.XlVAlign.xlVAlignCenter;
// Set Rows
foreach (DataGridViewRow row in grid.Rows) {
r++;
c = cMin;
// Set Cells
foreach (DataGridViewCell item in row.Cells) {
sheet.Cells[r, c++] = item.Value;
}
}
}
book.SaveAs(fileName, Type.Missing, Type.Missing, Type.Missing);
book.Close();
app.Quit();
}
catch (Exception ex) {
MessageBox.Show("Error writing to excel: " + ex.Message);
}
finally {
if (sheet != null)
Marshal.ReleaseComObject(sheet);
if (book != null)
Marshal.ReleaseComObject(book);
if (app != null)
Marshal.ReleaseComObject(app);
}
}
Hope this helps.

Simply Make a method and pass DataGridView
using Excel = Microsoft.Office.Interop.Excel;
public void ete(DataGridView dgv)//ExportToExcel
{
// Creating a Excel object.
Excel._Application excel = new Excel.Application();
Excel._Workbook workbook = excel.Workbooks.Add(Type.Missing);
Excel._Worksheet worksheet = null;
excel.Columns.ColumnWidth = 20;
try
{
worksheet = workbook.ActiveSheet;
worksheet.Name = "ExportedFromDatGrid";
int cellRowIndex = 1;
int cellColumnIndex = 1;
//Loop through each row and read value from each column.
for (int i = -1; i < dgv.Rows.Count; i++)
{
for (int j = 0; j < dgv.Columns.Count; j++)
{
// Excel index starts from 1,1. As first Row would have the Column headers, adding a condition check.
if (cellRowIndex == 1)
{
worksheet.Cells[cellRowIndex, cellColumnIndex] = dgv.Columns[j].HeaderText;
}
else
{
worksheet.Cells[cellRowIndex, cellColumnIndex] = dgv.Rows[i].Cells[j].Value.ToString();
}
cellColumnIndex++;
}
cellColumnIndex = 1;
cellRowIndex++;
}
//Getting the location and file name of the excel to save from user.
SaveFileDialog saveDialog = new SaveFileDialog();
saveDialog.Filter = "Excel files (*.xlsx)|*.xlsx|All files (*.*)|*.*";
saveDialog.FilterIndex = 2;
if (saveDialog.ShowDialog() == DialogResult.OK)
{
workbook.SaveAs(saveDialog.FileName.ToString());
MessageBox.Show("Export Successful");
}
}
catch (System.Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
excel.Quit();
workbook = null;
excel = null;
}
}
Now Call Method
ete(datagridview1);

How to read large excel file in asp.net c# by splitting it into simpler? [duplicate]

How to read an Excel file using C#? I open an Excel file for reading and copy it to clipboard to search email format, but I don't know how to do it.
FileInfo finfo;
Excel.ApplicationClass ExcelObj = new Excel.ApplicationClass();
ExcelObj.Visible = false;
Excel.Workbook theWorkbook;
Excel.Worksheet worksheet;
if (listView1.Items.Count > 0)
{
foreach (ListViewItem s in listView1.Items)
{
finfo = new FileInfo(s.Text);
if (finfo.Extension == ".xls" || finfo.Extension == ".xlsx" || finfo.Extension == ".xlt" || finfo.Extension == ".xlsm" || finfo.Extension == ".csv")
{
theWorkbook = ExcelObj.Workbooks.Open(s.Text, 0, true, 5, "", "", true, Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, false, false);
for (int count = 1; count <= theWorkbook.Sheets.Count; count++)
{
worksheet = (Excel.Worksheet)theWorkbook.Worksheets.get_Item(count);
worksheet.Activate();
worksheet.Visible = false;
worksheet.UsedRange.Cells.Select();
}
}
}
}

OK,
One of the more difficult concepts to grasp about Excel VSTO programming is that you don't refer to cells like an array, Worksheet[0][0] won't give you cell A1, it will error out on you. Even when you type into A1 when Excel is open, you are actually entering data into Range A1. Therefore you refer to cells as Named Ranges. Here's an example:
Excel.Worksheet sheet = workbook.Sheets["Sheet1"] as Excel.Worksheet;
Excel.Range range = sheet.get_Range("A1", Missing.Value)
You can now literally type:
range.Text // this will give you the text the user sees
range.Value2 // this will give you the actual value stored by Excel (without rounding)
If you want to do something like this:
Excel.Range range = sheet.get_Range("A1:A5", Missing.Value)
if (range1 != null)
foreach (Excel.Range r in range1)
{
string user = r.Text
string value = r.Value2
}
There might be a better way, but this has worked for me.
The reason you need to use Value2 and not Value is because the Value property is a parametrized and C# doesn't support them yet.
As for the cleanup code, i will post that when i get to work tomorrow, i don't have the code with me, but it's very boilerplate. You just close and release the objects in the reverse order you created them. You can't use a Using() block because the Excel.Application or Excel.Workbook doesn't implement IDisposable, and if you don't clean-up, you will be left with a hanging Excel objects in memory.
Note:
If you don't set the Visibility property Excel doesn't display, which can be disconcerting to your users, but if you want to just rip the data out, that is probably good enough
You could OleDb, that will work too.
I hope that gets you started, let me know if you need further clarification. I'll post a complete
here is a complete sample:
using System;
using System.IO;
using System.Reflection;
using NUnit.Framework;
using ExcelTools = Ms.Office;
using Excel = Microsoft.Office.Interop.Excel;
namespace Tests
{
[TestFixture]
public class ExcelSingle
{
[Test]
public void ProcessWorkbook()
{
string file = #"C:\Users\Chris\Desktop\TestSheet.xls";
Console.WriteLine(file);
Excel.Application excel = null;
Excel.Workbook wkb = null;
try
{
excel = new Excel.Application();
wkb = ExcelTools.OfficeUtil.OpenBook(excel, file);
Excel.Worksheet sheet = wkb.Sheets["Data"] as Excel.Worksheet;
Excel.Range range = null;
if (sheet != null)
range = sheet.get_Range("A1", Missing.Value);
string A1 = String.Empty;
if( range != null )
A1 = range.Text.ToString();
Console.WriteLine("A1 value: {0}", A1);
}
catch(Exception ex)
{
//if you need to handle stuff
Console.WriteLine(ex.Message);
}
finally
{
if (wkb != null)
ExcelTools.OfficeUtil.ReleaseRCM(wkb);
if (excel != null)
ExcelTools.OfficeUtil.ReleaseRCM(excel);
}
}
}
}
I'll post the functions from ExcelTools tomorrow, I don't have that code with me either.
Edit:
As promised, here are the Functions from ExcelTools you might need.
public static Excel.Workbook OpenBook(Excel.Application excelInstance, string fileName, bool readOnly, bool editable,
bool updateLinks) {
Excel.Workbook book = excelInstance.Workbooks.Open(
fileName, updateLinks, readOnly,
Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
Type.Missing, editable, Type.Missing, Type.Missing, Type.Missing,
Type.Missing, Type.Missing);
return book;
}
public static void ReleaseRCM(object o) {
try {
System.Runtime.InteropServices.Marshal.ReleaseComObject(o);
} catch {
} finally {
o = null;
}
}
To be frank, this stuff is much easier if you use VB.NET. It's in C# because I didn't write it. VB.NET does option parameters well, C# does not, hence the Type.Missing. Once you typed Type.Missing twice in a row, you run screaming from the room!
As for you question, you can try to following:
http://msdn.microsoft.com/en-us/library/microsoft.office.interop.excel.range.find(VS.80).aspx
I will post an example when I get back from my meeting... cheers
Edit: Here is an example
range = sheet.Cells.Find("Value to Find",
Type.Missing,
Type.Missing,
Type.Missing,
Type.Missing,
Excel.XlSearchDirection.xlNext,
Type.Missing,
Type.Missing, Type.Missing);
range.Text; //give you the value found
Here is another example inspired by this site:
range = sheet.Cells.Find("Value to find", Type.Missing, Type.Missing,Excel.XlLookAt.xlWhole,Excel.XlSearchOrder.xlByColumns,Excel.XlSearchDirection.xlNext,false, false, Type.Missing);
It helps to understand the parameters.
P.S. I'm one of those weird people who enjoys learning COM automation. All this code steamed from a tool I wrote for work which required me to process over 1000+ spreadsheets from the lab each Monday.

You can use Microsoft.Office.Interop.Excel assembly to process excel files.
Right click on your project and go to Add reference. Add the
Microsoft.Office.Interop.Excel assembly.
Include using
Microsoft.Office.Interop.Excel; to make use of assembly.
Here is the sample code:
using Microsoft.Office.Interop.Excel;
//create the Application object we can use in the member functions.
Microsoft.Office.Interop.Excel.Application _excelApp = new Microsoft.Office.Interop.Excel.Application();
_excelApp.Visible = true;
string fileName = "C:\\sampleExcelFile.xlsx";
//open the workbook
Workbook workbook = _excelApp.Workbooks.Open(fileName,
Type.Missing, Type.Missing, Type.Missing, Type.Missing,
Type.Missing, Type.Missing, Type.Missing, Type.Missing,
Type.Missing, Type.Missing, Type.Missing, Type.Missing,
Type.Missing, Type.Missing);
//select the first sheet
Worksheet worksheet = (Worksheet)workbook.Worksheets[1];
//find the used range in worksheet
Range excelRange = worksheet.UsedRange;
//get an object array of all of the cells in the worksheet (their values)
object[,] valueArray = (object[,])excelRange.get_Value(
XlRangeValueDataType.xlRangeValueDefault);
//access the cells
for (int row = 1; row <= worksheet.UsedRange.Rows.Count; ++row)
{
for (int col = 1; col <= worksheet.UsedRange.Columns.Count; ++col)
{
//access each cell
Debug.Print(valueArray[row, col].ToString());
}
}
//clean up stuffs
workbook.Close(false, Type.Missing, Type.Missing);
Marshal.ReleaseComObject(workbook);
_excelApp.Quit();
Marshal.FinalReleaseComObject(_excelApp);

Why don't you create OleDbConnection? There are a lot of available resources in the Internet. Here is an example
OleDbConnection con = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source="+filename+";Extended Properties=Excel 8.0");
con.Open();
try
{
//Create Dataset and fill with imformation from the Excel Spreadsheet for easier reference
DataSet myDataSet = new DataSet();
OleDbDataAdapter myCommand = new OleDbDataAdapter(" SELECT * FROM ["+listname+"$]" , con);
myCommand.Fill(myDataSet);
con.Close();
richTextBox1.AppendText("\nDataSet Filled");
//Travers through each row in the dataset
foreach (DataRow myDataRow in myDataSet.Tables[0].Rows)
{
//Stores info in Datarow into an array
Object[] cells = myDataRow.ItemArray;
//Traverse through each array and put into object cellContent as type Object
//Using Object as for some reason the Dataset reads some blank value which
//causes a hissy fit when trying to read. By using object I can convert to
//String at a later point.
foreach (object cellContent in cells)
{
//Convert object cellContect into String to read whilst replacing Line Breaks with a defined character
string cellText = cellContent.ToString();
cellText = cellText.Replace("\n", "|");
//Read the string and put into Array of characters chars
richTextBox1.AppendText("\n"+cellText);
}
}
//Thread.Sleep(15000);
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
//Thread.Sleep(15000);
}
finally
{
con.Close();
}

try
{
DataTable sheet1 = new DataTable("Excel Sheet");
OleDbConnectionStringBuilder csbuilder = new OleDbConnectionStringBuilder();
csbuilder.Provider = "Microsoft.ACE.OLEDB.12.0";
csbuilder.DataSource = fileLocation;
csbuilder.Add("Extended Properties", "Excel 12.0 Xml;HDR=YES");
string selectSql = #"SELECT * FROM [Sheet1$]";
using (OleDbConnection connection = new OleDbConnection(csbuilder.ConnectionString))
using (OleDbDataAdapter adapter = new OleDbDataAdapter(selectSql, connection))
{
connection.Open();
adapter.Fill(sheet1);
}
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
This worked for me. Please try it and let me know for queries.

First of all, it's important to know what you mean by "open an Excel file for reading and copy it to clipboard..."
This is very important because there are many ways you could do that depending just on what you intend to do. Let me explain:
If you want to read a set of data and copy that in the clipboard and you know the data format (e.g. column names), I suggest you use an OleDbConnection to open the file, this way you can treat the xls file content as a Database Table, so you can read data with SQL instruction and treat the data as you want.
If you want to do operations on the data with the Excel object model then open it in the way you began.
Some time it's possible to treat an xls file as a kind of csv file, there are tools like File Helpers which permit you to treat and open an xls file in a simple way by mapping a structure on an arbitrary object.
Another important point is in which Excel version the file is.
I have, unfortunately I say, a strong experience working with Office automation in all ways, even if bounded in concepts like Application Automation, Data Management and Plugins, and generally I suggest only as the last resort, to using Excel automation or Office automation to read data; just if there aren't better ways to accomplish that task.
Working with automation could be heavy in performance, in terms of resource cost, could involve in other issues related for example to security and more, and last but not at least, working with COM interop it's not so "free"..
So my suggestion is think and analyze the situation within your needs and then take the better way.

Here's a 2020 answer - if you don't need to support the older .xls format (so pre 2003) you could use either:
LightweightExcelReader to access specfic cells, or cursor through all the data in a spreadsheet.
or
ExcelToEnumerable if you want to map spreadsheet data to a list of objects.
Pros :
Performance - at the time of writing (the the fastest way to read an .xlsx file)[https://github.com/ChrisHodges/ExcelToEnumerable#performance].
Simplicity - less verbose than OLE DB or OpenXml
Cons:
Neither LightweightExcelReader nor ExcelToEnumerable support .xls files.
Disclaimer: I am the author of LightweightExcelReader and ExcelToEnumerable

Use Open XML.
Here is some code to process a spreadsheet with a specific tab or sheet name and dump it to something like CSV. (I chose a pipe instead of comma).
I wish it was easier to get the value from a cell, but I think this is what we are stuck with. You can see that I reference the MSDN documents where I got most of this code. That is what Microsoft recommends.
/// <summary>
/// Got code from: https://msdn.microsoft.com/en-us/library/office/gg575571.aspx
/// </summary>
[Test]
public void WriteOutExcelFile()
{
var fileName = "ExcelFiles\\File_With_Many_Tabs.xlsx";
var sheetName = "Submission Form"; // Existing tab name.
using (var document = SpreadsheetDocument.Open(fileName, isEditable: false))
{
var workbookPart = document.WorkbookPart;
var sheet = workbookPart.Workbook.Descendants<Sheet>().FirstOrDefault(s => s.Name == sheetName);
var worksheetPart = (WorksheetPart)(workbookPart.GetPartById(sheet.Id));
var sheetData = worksheetPart.Worksheet.Elements<SheetData>().First();
foreach (var row in sheetData.Elements<Row>())
{
foreach (var cell in row.Elements<Cell>())
{
Console.Write("|" + GetCellValue(cell, workbookPart));
}
Console.Write("\n");
}
}
}
/// <summary>
/// Got code from: https://msdn.microsoft.com/en-us/library/office/hh298534.aspx
/// </summary>
/// <param name="cell"></param>
/// <param name="workbookPart"></param>
/// <returns></returns>
private string GetCellValue(Cell cell, WorkbookPart workbookPart)
{
if (cell == null)
{
return null;
}
var value = cell.CellFormula != null
? cell.CellValue.InnerText
: cell.InnerText.Trim();
// If the cell represents an integer number, you are done.
// For dates, this code returns the serialized value that
// represents the date. The code handles strings and
// Booleans individually. For shared strings, the code
// looks up the corresponding value in the shared string
// table. For Booleans, the code converts the value into
// the words TRUE or FALSE.
if (cell.DataType == null)
{
return value;
}
switch (cell.DataType.Value)
{
case CellValues.SharedString:
// For shared strings, look up the value in the
// shared strings table.
var stringTable =
workbookPart.GetPartsOfType<SharedStringTablePart>()
.FirstOrDefault();
// If the shared string table is missing, something
// is wrong. Return the index that is in
// the cell. Otherwise, look up the correct text in
// the table.
if (stringTable != null)
{
value =
stringTable.SharedStringTable
.ElementAt(int.Parse(value)).InnerText;
}
break;
case CellValues.Boolean:
switch (value)
{
case "0":
value = "FALSE";
break;
default:
value = "TRUE";
break;
}
break;
}
return value;
}

Use OLEDB Connection to communicate with excel files. it gives better result
using System.Data.OleDb;
string physicalPath = "Your Excel file physical path";
OleDbCommand cmd = new OleDbCommand();
OleDbDataAdapter da = new OleDbDataAdapter();
DataSet ds = new DataSet();
String strNewPath = physicalPath;
String connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + strNewPath + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";
String query = "SELECT * FROM [Sheet1$]"; // You can use any different queries to get the data from the excel sheet
OleDbConnection conn = new OleDbConnection(connString);
if (conn.State == ConnectionState.Closed) conn.Open();
try
{
cmd = new OleDbCommand(query, conn);
da = new OleDbDataAdapter(cmd);
da.Fill(ds);
}
catch
{
// Exception Msg
}
finally
{
da.Dispose();
conn.Close();
}
The Output data will be stored in dataset, using the dataset object you can easily access the datas.
Hope this may helpful

Using OlebDB, we can read excel file in C#, easily, here is the code while working with Web-Form, where FileUpload1 is file uploading tool
string path = Server.MapPath("~/Uploads/");
if (!Directory.Exists(path))
{
Directory.CreateDirectory(path);
}
//get file path
filePath = path + Path.GetFileName(FileUpload1.FileName);
//get file extenstion
string extension = Path.GetExtension(FileUpload1.FileName);
//save file on "Uploads" folder of project
FileUpload1.SaveAs(filePath);
string conString = string.Empty;
//check file extension
switch (extension)
{
case ".xls": //Excel 97-03.
conString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Excel03ConString;Extended Properties='Excel 8.0;HDR=YES'";
break;
case ".xlsx": //Excel 07 and above.
conString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Excel07ConString;Extended Properties='Excel 8.0;HDR=YES'";
break;
}
//create datatable object
DataTable dt = new DataTable();
conString = string.Format(conString, filePath);
//Use OldDb to read excel
using (OleDbConnection connExcel = new OleDbConnection(conString))
{
using (OleDbCommand cmdExcel = new OleDbCommand())
{
using (OleDbDataAdapter odaExcel = new OleDbDataAdapter())
{
cmdExcel.Connection = connExcel;
//Get the name of First Sheet.
connExcel.Open();
DataTable dtExcelSchema;
dtExcelSchema = connExcel.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
string sheetName = dtExcelSchema.Rows[0]["TABLE_NAME"].ToString();
connExcel.Close();
//Read Data from First Sheet.
connExcel.Open();
cmdExcel.CommandText = "SELECT * From [" + sheetName + "]";
odaExcel.SelectCommand = cmdExcel;
odaExcel.Fill(dt);
connExcel.Close();
}
}
}
//bind datatable with GridView
GridView1.DataSource = dt;
GridView1.DataBind();
Source : https://qawithexperts.com/article/asp-net/read-excel-file-and-import-data-into-gridview-using-datatabl/209
Console application similar code example
https://qawithexperts.com/article/c-sharp/read-excel-file-in-c-console-application-example-using-oledb/168
If you need don't want to use OleDB, you can try https://github.com/ExcelDataReader/ExcelDataReader
which seems to have the ability to handle both formats (.xls and .xslx)

Excel File Reader & Writer Without Excel On u'r System
Download and add the dll for
NPOI u'r project.
Using this code to read a excel file.
using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
XSSFWorkbook XSSFWorkbook = new XSSFWorkbook(file);
}
ISheet objxlWorkSheet = XSSFWorkbook.GetSheetAt(0);
int intRowCount = 1;
int intColumnCount = 0;
for (; ; )
{
IRow Row = objxlWorkSheet.GetRow(intRowCount);
if (Row != null)
{
ICell Cell = Row.GetCell(0);
ICell objCell = objxlWorkSheet.GetRow(intRowCount).GetCell(intColumnCount); }}

You can use ExcelDataReader see GitHub
You need to install nugets :
-ExcelDataReader
-ExcelDataReader.DataSet
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.IO;
using ExcelDataReader;
using System.Text;
/// <summary>
/// Excel parsing in this class is performed by using a common shareware Lib found on:
/// https://github.com/ExcelDataReader/ExcelDataReader
/// </summary>
public static class ExcelParser
{
/// <summary>
/// Load, read and get values from Excel sheet
/// </summary>
public static List<FileRow> GetExcelRows(string path, string sheetName, bool skipFirstLine)
{
if (File.Exists(path))
{
return GetValues(path, sheetName, skipFirstLine);
}
else
throw new Exception("The process cannot access the file");
}
/// <summary>
/// Parse sheet names from given Excel file.
/// </summary>
public static List<string> GetSheetNames(string path)
{
using (var stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
{
Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
using (var excelReader = GetExcelDataReader(path, stream))
{
var dataset = excelReader.AsDataSet(new ExcelDataSetConfiguration()
{
ConfigureDataTable = (_) => new ExcelDataTableConfiguration()
{
UseHeaderRow = true
}
});
var names = from DataTable table in dataset.Tables
select table.TableName;
return names.ToList();
}
}
}
/// <summary>
/// Parse values from Excel sheet and add to Rows collection.
/// </summary>
public static List<FileRow> GetValues(string path, string sheetName, bool skipFirstLine)
{
var rowItems = new List<FileRow>();
using (var stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
{
using (var excelReader = GetExcelDataReader(path, stream))
{
var dataset = excelReader.AsDataSet(new ExcelDataSetConfiguration()
{
ConfigureDataTable = (_) => new ExcelDataTableConfiguration()
{
UseHeaderRow = skipFirstLine
}
});
foreach (DataRow row in dataset.Tables[sheetName].Rows)
{
var rowItem = new FileRow();
foreach (var value in row.ItemArray)
rowItem.Values.Add(value);
rowItems.Add(rowItem);
}
}
}
return rowItems;
}
private static IExcelDataReader GetExcelDataReader(string path, Stream stream)
{
var extension = GetExtension(path);
switch (extension)
{
case "xls":
return ExcelReaderFactory.CreateBinaryReader(stream);
case "xlsx":
return ExcelReaderFactory.CreateOpenXmlReader(stream);
default:
throw new Exception(string.Format("'{0}' is not a valid Excel extension", extension));
}
}
private static string GetExtension(string path)
{
var extension = Path.GetExtension(path);
return extension == null ? null : extension.ToLower().Substring(1);
}
}
With this entity :
public class FileRow
{
public List<object> Values { get; set; }
public FileRow()
{
Values = new List<object>();
}
}
Use like that :
var txtPath = #"D:\Path\excelfile.xlsx";
var sheetNames = ExcelParser.GetSheetNames(txtPath);
var datas = ExcelParser.GetExcelRows(txtPath, sheetNames[0], true);

The recommended way to read Excel files on server side app is Open XML.
Sharing few links -
https://msdn.microsoft.com/en-us/library/office/hh298534.aspx
https://msdn.microsoft.com/en-us/library/office/ff478410.aspx
https://msdn.microsoft.com/en-us/library/office/cc823095.aspx

public void excelRead(string sheetName)
{
Excel.Application appExl = new Excel.Application();
Excel.Workbook workbook = null;
try
{
string methodName = "";
Excel.Worksheet NwSheet;
Excel.Range ShtRange;
//Opening Excel file(myData.xlsx)
appExl = new Excel.Application();
workbook = appExl.Workbooks.Open(sheetName, Missing.Value, ReadOnly: false);
NwSheet = (Excel.Worksheet)workbook.Sheets.get_Item(1);
ShtRange = NwSheet.UsedRange; //gives the used cells in sheet
int rCnt1 = 0;
int cCnt1 = 0;
for (rCnt1 = 1; rCnt1 <= ShtRange.Rows.Count; rCnt1++)
{
for (cCnt1 = 1; cCnt1 <= ShtRange.Columns.Count; cCnt1++)
{
if (Convert.ToString(NwSheet.Cells[rCnt1, cCnt1].Value2) == "Y")
{
methodName = NwSheet.Cells[rCnt1, cCnt1 - 2].Value2;
Type metdType = this.GetType();
MethodInfo mthInfo = metdType.GetMethod(methodName);
if (Convert.ToString(NwSheet.Cells[rCnt1, cCnt1 - 2].Value2) == "fn_AddNum" || Convert.ToString(NwSheet.Cells[rCnt1, cCnt1 - 2].Value2) == "fn_SubNum")
{
StaticVariable.intParam1 = Convert.ToInt32(NwSheet.Cells[rCnt1, cCnt1 + 3].Value2);
StaticVariable.intParam2 = Convert.ToInt32(NwSheet.Cells[rCnt1, cCnt1 + 4].Value2);
object[] mParam1 = new object[] { StaticVariable.intParam1, StaticVariable.intParam2 };
object result = mthInfo.Invoke(this, mParam1);
StaticVariable.intOutParam1 = Convert.ToInt32(result);
NwSheet.Cells[rCnt1, cCnt1 + 5].Value2 = Convert.ToString(StaticVariable.intOutParam1) != "" ? Convert.ToString(StaticVariable.intOutParam1) : String.Empty;
}
else
{
object[] mParam = new object[] { };
mthInfo.Invoke(this, mParam);
NwSheet.Cells[rCnt1, cCnt1 + 5].Value2 = StaticVariable.outParam1 != "" ? StaticVariable.outParam1 : String.Empty;
NwSheet.Cells[rCnt1, cCnt1 + 6].Value2 = StaticVariable.outParam2 != "" ? StaticVariable.outParam2 : String.Empty;
}
NwSheet.Cells[rCnt1, cCnt1 + 1].Value2 = StaticVariable.resultOut;
NwSheet.Cells[rCnt1, cCnt1 + 2].Value2 = StaticVariable.resultDescription;
}
else if (Convert.ToString(NwSheet.Cells[rCnt1, cCnt1].Value2) == "N")
{
MessageBox.Show("Result is No");
}
else if (Convert.ToString(NwSheet.Cells[rCnt1, cCnt1].Value2) == "EOF")
{
MessageBox.Show("End of File");
}
}
}
workbook.Save();
workbook.Close(true, Missing.Value, Missing.Value);
appExl.Quit();
System.Runtime.InteropServices.Marshal.FinalReleaseComObject(ShtRange);
System.Runtime.InteropServices.Marshal.FinalReleaseComObject(NwSheet);
System.Runtime.InteropServices.Marshal.FinalReleaseComObject(workbook);
System.Runtime.InteropServices.Marshal.FinalReleaseComObject(appExl);
}
catch (Exception)
{
workbook.Close(true, Missing.Value, Missing.Value);
}
finally
{
GC.Collect();
GC.WaitForPendingFinalizers();
System.Runtime.InteropServices.Marshal.CleanupUnusedObjectsInCurrentContext();
}
}
//code for reading excel data in datatable
public void testExcel(string sheetName)
{
try
{
MessageBox.Show(sheetName);
foreach(Process p in Process.GetProcessesByName("EXCEL"))
{
p.Kill();
}
//string fileName = "E:\\inputSheet";
Excel.Application oXL;
Workbook oWB;
Worksheet oSheet;
Range oRng;
// creat a Application object
oXL = new Excel.Application();
// get WorkBook object
oWB = oXL.Workbooks.Open(sheetName);
// get WorkSheet object
oSheet = (Microsoft.Office.Interop.Excel.Worksheet)oWB.Sheets[1];
System.Data.DataTable dt = new System.Data.DataTable();
//DataSet ds = new DataSet();
//ds.Tables.Add(dt);
DataRow dr;
StringBuilder sb = new StringBuilder();
int jValue = oSheet.UsedRange.Cells.Columns.Count;
int iValue = oSheet.UsedRange.Cells.Rows.Count;
// get data columns
for (int j = 1; j <= jValue; j++)
{
oRng = (Microsoft.Office.Interop.Excel.Range)oSheet.Cells[1, j];
string strValue = oRng.Text.ToString();
dt.Columns.Add(strValue, System.Type.GetType("System.String"));
}
//string colString = sb.ToString().Trim();
//string[] colArray = colString.Split(':');
// get data in cell
for (int i = 2; i <= iValue; i++)
{
dr = dt.NewRow();
for (int j = 1; j <= jValue; j++)
{
oRng = (Microsoft.Office.Interop.Excel.Range)oSheet.Cells[i, j];
string strValue = oRng.Text.ToString();
dr[j - 1] = strValue;
}
dt.Rows.Add(dr);
}
if(StaticVariable.dtExcel != null)
{
StaticVariable.dtExcel.Clear();
StaticVariable.dtExcel = dt.Copy();
}
else
StaticVariable.dtExcel = dt.Copy();
oWB.Close(true, Missing.Value, Missing.Value);
oXL.Quit();
MessageBox.Show(sheetName);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
}
}
//code for class initialize
public static void startTesting(TestContext context)
{
Playback.Initialize();
ReadExcel myClassObj = new ReadExcel();
string sheetName="";
StreamReader sr = new StreamReader(#"E:\SaveSheetName.txt");
sheetName = sr.ReadLine();
sr.Close();
myClassObj.excelRead(sheetName);
myClassObj.testExcel(sheetName);
}
//code for test initalize
public void runValidatonTest()
{
DataTable dtFinal = StaticVariable.dtExcel.Copy();
for (int i = 0; i < dtFinal.Rows.Count; i++)
{
if (TestContext.TestName == dtFinal.Rows[i][2].ToString() && dtFinal.Rows[i][3].ToString() == "Y" && dtFinal.Rows[i][4].ToString() == "TRUE")
{
MessageBox.Show(TestContext.TestName);
MessageBox.Show(dtFinal.Rows[i][2].ToString());
StaticVariable.runValidateResult = "true";
break;
}
}
//StaticVariable.dtExcel = dtFinal.Copy();
}

I'd recommend you to use Bytescout Spreadsheet.
https://bytescout.com/products/developer/spreadsheetsdk/bytescoutspreadsheetsdk.html
I tried it with Monodevelop in Unity3D and it is pretty straight forward. Check this sample code to see how the library works:
https://bytescout.com/products/developer/spreadsheetsdk/read-write-excel.html

How to create(export) excel file readonly using Open Xml 2.5 SDK

I am developing one WPF application (using MVVM). I am also able to export my List to Excel file.But my problem is I am not able to make it readonly, so no one can able to make changes afterwards.
document.WorkbookPart.Workbook.WorkbookProtection=new WorkbookProtection
{
LockStructure=true
};
I only found this, but it's only make workbook readonly
Here is my code for creating excel file
public static bool CreateExcelDocument(DataSet ds, string excelFilename)
{
try
{
using (SpreadsheetDocument document = SpreadsheetDocument.Create(excelFilename, SpreadsheetDocumentType.Workbook))
{
document.AddWorkbookPart();
document.WorkbookPart.Workbook = new DocumentFormat.OpenXml.Spreadsheet.Workbook();
document.WorkbookPart.Workbook.WorkbookProtection=new WorkbookProtection
{
LockStructure = true,
};
// My thanks to James Miera for the following line of code (which prevents crashes in Excel 2010)
document.WorkbookPart.Workbook.Append(new BookViews(new WorkbookView()));
// If we don't add a "WorkbookStylesPart", OLEDB will refuse to connect to this .xlsx file !
WorkbookStylesPart workbookStylesPart = document.WorkbookPart.AddNewPart<WorkbookStylesPart>("rIdStyles");
Stylesheet stylesheet = new Stylesheet();
workbookStylesPart.Stylesheet = stylesheet;
CreateParts(ds, document);
}
Trace.WriteLine("Successfully created: " + excelFilename);
return true;
}
catch (Exception ex)
{
Trace.WriteLine("Failed, exception thrown: " + ex.Message);
return false;
}
}
private static void CreateParts(DataSet ds, SpreadsheetDocument spreadsheet)
{
// Loop through each of the DataTables in our DataSet, and create a new Excel Worksheet for each.
uint worksheetNumber = 1;
foreach (DataTable dt in ds.Tables)
{
// For each worksheet you want to create
string workSheetID = "rId" + worksheetNumber.ToString();
string worksheetName = dt.TableName;
WorksheetPart newWorksheetPart = spreadsheet.WorkbookPart.AddNewPart<WorksheetPart>();
newWorksheetPart.Worksheet = new DocumentFormat.OpenXml.Spreadsheet.Worksheet();
// create sheet data
newWorksheetPart.Worksheet.AppendChild(new DocumentFormat.OpenXml.Spreadsheet.SheetData());
// save worksheet
WriteDataTableToExcelWorksheet(dt, newWorksheetPart);
newWorksheetPart.Worksheet.Save();
// create the worksheet to workbook relation
if (worksheetNumber == 1)
spreadsheet.WorkbookPart.Workbook.AppendChild(new DocumentFormat.OpenXml.Spreadsheet.Sheets());
spreadsheet.WorkbookPart.Workbook.GetFirstChild<DocumentFormat.OpenXml.Spreadsheet.Sheets>().AppendChild(new DocumentFormat.OpenXml.Spreadsheet.Sheet()
{
Id = spreadsheet.WorkbookPart.GetIdOfPart(newWorksheetPart),
SheetId = (uint)worksheetNumber,
Name = dt.TableName
});
worksheetNumber++;
}
spreadsheet.WorkbookPart.Workbook.Save();
}

Before you open Excel, you can Lock your file with:
FileInfo cInfo = new FileInfo(Path);
cInfo.IsReadonly = true;
Than it will be readonly.

Is there any simple way to convert .xls file to .csv file? (Excel)

Is there any simple way to convert .xls file to .csv file ? (Excel)
in C# code ?
I mean to take an existing .xls file and convert them to .csv file

Here's a C# method to do this. Remember to add your own error handling - this mostly assumes that things work for the sake of brevity. It's 4.0+ framework only, but that's mostly because of the optional worksheetNumber parameter. You can overload the method if you need to support earlier versions.
static void ConvertExcelToCsv(string excelFilePath, string csvOutputFile, int worksheetNumber = 1) {
if (!File.Exists(excelFilePath)) throw new FileNotFoundException(excelFilePath);
if (File.Exists(csvOutputFile)) throw new ArgumentException("File exists: " + csvOutputFile);
// connection string
var cnnStr = String.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=\"Excel 8.0;IMEX=1;HDR=NO\"", excelFilePath);
var cnn = new OleDbConnection(cnnStr);
// get schema, then data
var dt = new DataTable();
try {
cnn.Open();
var schemaTable = cnn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
if (schemaTable.Rows.Count < worksheetNumber) throw new ArgumentException("The worksheet number provided cannot be found in the spreadsheet");
string worksheet = schemaTable.Rows[worksheetNumber - 1]["table_name"].ToString().Replace("'", "");
string sql = String.Format("select * from [{0}]", worksheet);
var da = new OleDbDataAdapter(sql, cnn);
da.Fill(dt);
}
catch (Exception e) {
// ???
throw e;
}
finally {
// free resources
cnn.Close();
}
// write out CSV data
using (var wtr = new StreamWriter(csvOutputFile)) {
foreach (DataRow row in dt.Rows) {
bool firstLine = true;
foreach (DataColumn col in dt.Columns) {
if (!firstLine) { wtr.Write(","); } else { firstLine = false; }
var data = row[col.ColumnName].ToString().Replace("\"", "\"\"");
wtr.Write(String.Format("\"{0}\"", data));
}
wtr.WriteLine();
}
}
}

Checkout the .SaveAs() method in Excel object.
wbWorkbook.SaveAs("c:\yourdesiredFilename.csv", Microsoft.Office.Interop.Excel.XlFileFormat.xlCSV)
Or following:
public static void SaveAs()
{
Microsoft.Office.Interop.Excel.Application app = new Microsoft.Office.Interop.Excel.ApplicationClass();
Microsoft.Office.Interop.Excel.Workbook wbWorkbook = app.Workbooks.Add(Type.Missing);
Microsoft.Office.Interop.Excel.Sheets wsSheet = wbWorkbook.Worksheets;
Microsoft.Office.Interop.Excel.Worksheet CurSheet = (Microsoft.Office.Interop.Excel.Worksheet)wsSheet[1];
Microsoft.Office.Interop.Excel.Range thisCell = (Microsoft.Office.Interop.Excel.Range)CurSheet.Cells[1, 1];
thisCell.Value2 = "This is a test.";
wbWorkbook.SaveAs(#"c:\one.xls", Microsoft.Office.Interop.Excel.XlFileFormat.xlWorkbookNormal, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlShared, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
wbWorkbook.SaveAs(#"c:\two.csv", Microsoft.Office.Interop.Excel.XlFileFormat.xlCSVWindows, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlShared, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
wbWorkbook.Close(false, "", true);
}

Install these 2 packages
<packages>
<package id="ExcelDataReader" version="3.3.0" targetFramework="net451" />
<package id="ExcelDataReader.DataSet" version="3.3.0" targetFramework="net451" />
</packages>
Helper function
using ExcelDataReader;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ExcelToCsv
{
public class ExcelFileHelper
{
public static bool SaveAsCsv(string excelFilePath, string destinationCsvFilePath)
{
using (var stream = new FileStream(excelFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
IExcelDataReader reader = null;
if (excelFilePath.EndsWith(".xls"))
{
reader = ExcelReaderFactory.CreateBinaryReader(stream);
}
else if (excelFilePath.EndsWith(".xlsx"))
{
reader = ExcelReaderFactory.CreateOpenXmlReader(stream);
}
if (reader == null)
return false;
var ds = reader.AsDataSet(new ExcelDataSetConfiguration()
{
ConfigureDataTable = (tableReader) => new ExcelDataTableConfiguration()
{
UseHeaderRow = false
}
});
var csvContent = string.Empty;
int row_no = 0;
while (row_no < ds.Tables[0].Rows.Count)
{
var arr = new List<string>();
for (int i = 0; i < ds.Tables[0].Columns.Count; i++)
{
arr.Add(ds.Tables[0].Rows[row_no][i].ToString());
}
row_no++;
csvContent += string.Join(",", arr) + "\n";
}
StreamWriter csv = new StreamWriter(destinationCsvFilePath, false);
csv.Write(csvContent);
csv.Close();
return true;
}
}
}
}
Usage :
var excelFilePath = Console.ReadLine();
string output = Path.ChangeExtension(excelFilePath, ".csv");
ExcelFileHelper.SaveAsCsv(excelFilePath, output);

I had to come up with a hybrid solution after updating to Visual Studio 2022 and testing the most relevant answers for this to work.
First, we need to install the following Nuget packages: ExcelDataReader, ExcelDataReader.DataSet and System.Text.Encoding.CodePages
Then, for the sake of clean architecture, proceed to create a separate class within your corresponding namespace:
using ExcelDataReader;
using System.Collections.Generic;
using System.IO;
using System.Text;
namespace YourProjectNameSpace
{
public class ExcelFileHelper
{
/// <summary>
/// Converts a given XLS into CSV file format.
/// </summary>
public static bool SaveAsCsv(string excelFilePath, string destinationCsvFilePath)
{
Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
using (var stream = new FileStream(excelFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
IExcelDataReader reader = null;
if (excelFilePath.EndsWith(".xls"))
{
reader = ExcelReaderFactory.CreateBinaryReader(stream);
}
else if (excelFilePath.EndsWith(".xlsx"))
{
reader = ExcelReaderFactory.CreateOpenXmlReader(stream);
}
if (reader == null)
return false;
var ds = reader.AsDataSet(new ExcelDataSetConfiguration()
{
ConfigureDataTable = (tableReader) => new ExcelDataTableConfiguration()
{
UseHeaderRow = false
}
});
var csvContent = string.Empty;
int row_no = 0;
while (row_no < ds.Tables[0].Rows.Count)
{
var arr = new List<string>();
for (int i = 0; i < ds.Tables[0].Columns.Count; i++)
{
arr.Add(ds.Tables[0].Rows[row_no][i].ToString());
}
row_no++;
csvContent += string.Join(",", arr) + "\n";
}
StreamWriter csv = new StreamWriter(destinationCsvFilePath, false);
csv.Write(csvContent);
csv.Close();
return true;
}
}
}
}
Notice I had to include this line at the beginning of the function:
Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
If the line from above is omitted, you could end up getting the following error:
NotSupportedException: No data is available for encoding 1252
So, make sure of using it for better compatibility.
Finally, use example:
var execPath = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase)?.Replace("file:\\", "");
string FileNameXLS = "\\file.xls";
string FileNameCSV = "\\file.csv";
Console.WriteLine("Exporting file to CSV...." + "\n");
ExcelFileHelper.SaveAsCsv(execPath + FileNameXLS, execPath + FileNameCSV);
Console.WriteLine("File exported to CSV!" + "\n");

I need to do the same thing. I ended up with something similar to Kman
static void ExcelToCSVCoversion(string sourceFile, string targetFile)
{
Application rawData = new Application();
try
{
Workbook workbook = rawData.Workbooks.Open(sourceFile);
Worksheet ws = (Worksheet) workbook.Sheets[1];
ws.SaveAs(targetFile, XlFileFormat.xlCSV);
Marshal.ReleaseComObject(ws);
}
finally
{
rawData.DisplayAlerts = false;
rawData.Quit();
Marshal.ReleaseComObject(rawData);
}
Console.WriteLine();
Console.WriteLine($"The excel file {sourceFile} has been converted into {targetFile} (CSV format).");
Console.WriteLine();
}
If there are multiple sheets this is lost in the conversion but you could loop over the number of sheets and save each one as csv.

This is a modification of nate_weldon's answer with a few improvements:
More robust releasing of Excel objects
Set application.DisplayAlerts = false; before attempting to save to hide prompts
Also note that the application.Workbooks.Open and ws.SaveAs methods expect sourceFilePath and targetFilePath to be full paths (ie. directory path + filename)
private static void SaveAs(string sourceFilePath, string targetFilePath)
{
Application application = null;
Workbook wb = null;
Worksheet ws = null;
try
{
application = new Application();
application.DisplayAlerts = false;
wb = application.Workbooks.Open(sourceFilePath);
ws = (Worksheet)wb.Sheets[1];
ws.SaveAs(targetFilePath, XlFileFormat.xlCSV);
}
catch (Exception e)
{
// Handle exception
}
finally
{
if (application != null) application.Quit();
if (ws != null) Marshal.ReleaseComObject(ws);
if (wb != null) Marshal.ReleaseComObject(wb);
if (application != null) Marshal.ReleaseComObject(application);
}
}

I integrate the #mattmc3 aswer. If you want to convert a xlsx file you should use this connection string (the string provided by matt works for xls formats, not xlsx):
var cnnStr = String.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties=\"Excel 12.0;IMEX=1;HDR=NO\"", excelFilePath);

I had a similar task issue. Convert an inbound transactions like xlsx to tab delimited for automated processing by an existing system. Needs to run unattended. After reviewing many solutions on several different sites, and trying two of them, using MS Office Excel for C#, like above, and running into issues with different versions of MS Office, and older versions possibly on the PC, and having no control over that. I ended up going with... Aspose.Cells through NuGet. Solution is four lines of code.
string soureFilePath = "my/source/path/file.xlsx";
string targetFilePath = "my/output/path/file.txt";
var book = new Workbook(soureFilePath);
book.Save(targetFilePath, SaveFormat.Tsv);
It only converts sheet 1, and ignored sheets 2 and 3, but that is Ok for my use. I'm guessing it does have functionality to convert all of them if needed, I just did not need that, so did not look into it.
Their web site, incase folks want to view their information or license agreement (no cost use).
Manipulate Spreadsheets Easily | Aspose.Cells Universal Library
https://products.aspose.com/cells
Note: I do not work for Aspose, I am not affiliated with Aspose, and I am not profiting in any way from this posting.

I maintain some libraries that make the Excel to CSV conversion about as simple as it can be: Sylvan.Data.Excel and Sylvan.Data.Csv. Sylvan.Data.Excel can be used to read .xlsx, .xlsb, and .xls files. However, it can only write .xlsx files.
Here is a minimal example of converting an Excel spreadsheet to CSV:
using Sylvan.Data.Csv;
using Sylvan.Data.Excel;
using var reader = ExcelDataReader.Create("MyData.xlsx");
using var csvWriter = CsvDataWriter.Create("MyData.csv");
csvWriter.Write(reader);
These libraries have no external dependencies, other than the .NET runtime libraries; they don't require Excel be installed. They target the latest supported .NET versions and can run cross-platform. They are also the fastest libraries in the .NET ecosystem. They are MIT licensed, so can be freely used.

c# (WinForms-App) export DataSet to Excel

I need a solution to export a dataset to an excel file without any asp code (HttpResonpsne...) but i did not find a good example to do this...
Best thanks in advance

I've created a class that exports a DataGridView or DataTable to an Excel file. You can probably change it a bit to make it use your DataSet instead (iterating through the DataTables in it). It also does some basic formatting which you could also extend.
To use it, simply call ExcelExport, and specify a filename and whether to open the file automatically or not after exporting. I also could have made them extension methods, but I didn't. Feel free to.
Note that Excel files can be saved as a glorified XML document and this makes use of that.
EDIT: This used to use a vanilla StreamWriter, but as pointed out, things would not be escaped correctly in many cases. Now it uses a XmlWriter, which will do the escaping for you.
The ExcelWriter class wraps an XmlWriter. I haven't bothered, but you might want to do a bit more error checking to make sure you can't write cell data before starting a row, and such. The code is below.
public class ExcelWriter : IDisposable
{
private XmlWriter _writer;
public enum CellStyle { General, Number, Currency, DateTime, ShortDate };
public void WriteStartDocument()
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
_writer.WriteProcessingInstruction("mso-application", "progid=\"Excel.Sheet\"");
_writer.WriteStartElement("ss", "Workbook", "urn:schemas-microsoft-com:office:spreadsheet");
WriteExcelStyles();
}
public void WriteEndDocument()
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
_writer.WriteEndElement();
}
private void WriteExcelStyleElement(CellStyle style)
{
_writer.WriteStartElement("Style", "urn:schemas-microsoft-com:office:spreadsheet");
_writer.WriteAttributeString("ID", "urn:schemas-microsoft-com:office:spreadsheet", style.ToString());
_writer.WriteEndElement();
}
private void WriteExcelStyleElement(CellStyle style, string NumberFormat)
{
_writer.WriteStartElement("Style", "urn:schemas-microsoft-com:office:spreadsheet");
_writer.WriteAttributeString("ID", "urn:schemas-microsoft-com:office:spreadsheet", style.ToString());
_writer.WriteStartElement("NumberFormat", "urn:schemas-microsoft-com:office:spreadsheet");
_writer.WriteAttributeString("Format", "urn:schemas-microsoft-com:office:spreadsheet", NumberFormat);
_writer.WriteEndElement();
_writer.WriteEndElement();
}
private void WriteExcelStyles()
{
_writer.WriteStartElement("Styles", "urn:schemas-microsoft-com:office:spreadsheet");
WriteExcelStyleElement(CellStyle.General);
WriteExcelStyleElement(CellStyle.Number, "General Number");
WriteExcelStyleElement(CellStyle.DateTime, "General Date");
WriteExcelStyleElement(CellStyle.Currency, "Currency");
WriteExcelStyleElement(CellStyle.ShortDate, "Short Date");
_writer.WriteEndElement();
}
public void WriteStartWorksheet(string name)
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
_writer.WriteStartElement("Worksheet", "urn:schemas-microsoft-com:office:spreadsheet");
_writer.WriteAttributeString("Name", "urn:schemas-microsoft-com:office:spreadsheet", name);
_writer.WriteStartElement("Table", "urn:schemas-microsoft-com:office:spreadsheet");
}
public void WriteEndWorksheet()
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
_writer.WriteEndElement();
_writer.WriteEndElement();
}
public ExcelWriter(string outputFileName)
{
XmlWriterSettings settings = new XmlWriterSettings();
settings.Indent = true;
_writer = XmlWriter.Create(outputFileName, settings);
}
public void Close()
{
if (_writer == null) throw new InvalidOperationException("Already closed.");
_writer.Close();
_writer = null;
}
public void WriteExcelColumnDefinition(int columnWidth)
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
_writer.WriteStartElement("Column", "urn:schemas-microsoft-com:office:spreadsheet");
_writer.WriteStartAttribute("Width", "urn:schemas-microsoft-com:office:spreadsheet");
_writer.WriteValue(columnWidth);
_writer.WriteEndAttribute();
_writer.WriteEndElement();
}
public void WriteExcelUnstyledCell(string value)
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
_writer.WriteStartElement("Cell", "urn:schemas-microsoft-com:office:spreadsheet");
_writer.WriteStartElement("Data", "urn:schemas-microsoft-com:office:spreadsheet");
_writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "String");
_writer.WriteValue(value);
_writer.WriteEndElement();
_writer.WriteEndElement();
}
public void WriteStartRow()
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
_writer.WriteStartElement("Row", "urn:schemas-microsoft-com:office:spreadsheet");
}
public void WriteEndRow()
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
_writer.WriteEndElement();
}
public void WriteExcelStyledCell(object value, CellStyle style)
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
_writer.WriteStartElement("Cell", "urn:schemas-microsoft-com:office:spreadsheet");
_writer.WriteAttributeString("StyleID", "urn:schemas-microsoft-com:office:spreadsheet", style.ToString());
_writer.WriteStartElement("Data", "urn:schemas-microsoft-com:office:spreadsheet");
switch (style)
{
case CellStyle.General:
_writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "String");
break;
case CellStyle.Number:
case CellStyle.Currency:
_writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "Number");
break;
case CellStyle.ShortDate:
case CellStyle.DateTime:
_writer.WriteAttributeString("Type", "urn:schemas-microsoft-com:office:spreadsheet", "DateTime");
break;
}
_writer.WriteValue(value);
// tag += String.Format("{1}\"><ss:Data ss:Type=\"DateTime\">{0:yyyy\\-MM\\-dd\\THH\\:mm\\:ss\\.fff}</ss:Data>", value,
_writer.WriteEndElement();
_writer.WriteEndElement();
}
public void WriteExcelAutoStyledCell(object value)
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
//write the <ss:Cell> and <ss:Data> tags for something
if (value is Int16 || value is Int32 || value is Int64 || value is SByte ||
value is UInt16 || value is UInt32 || value is UInt64 || value is Byte)
{
WriteExcelStyledCell(value, CellStyle.Number);
}
else if (value is Single || value is Double || value is Decimal) //we'll assume it's a currency
{
WriteExcelStyledCell(value, CellStyle.Currency);
}
else if (value is DateTime)
{
//check if there's no time information and use the appropriate style
WriteExcelStyledCell(value, ((DateTime)value).TimeOfDay.CompareTo(new TimeSpan(0, 0, 0, 0, 0)) == 0 ? CellStyle.ShortDate : CellStyle.DateTime);
}
else
{
WriteExcelStyledCell(value, CellStyle.General);
}
}
#region IDisposable Members
public void Dispose()
{
if (_writer == null)
return;
_writer.Close();
_writer = null;
}
#endregion
}
Then you can export your DataTable using the following:
public static void ExcelExport(DataTable data, String fileName, bool openAfter)
{
//export a DataTable to Excel
DialogResult retry = DialogResult.Retry;
while (retry == DialogResult.Retry)
{
try
{
using (ExcelWriter writer = new ExcelWriter(fileName))
{
writer.WriteStartDocument();
// Write the worksheet contents
writer.WriteStartWorksheet("Sheet1");
//Write header row
writer.WriteStartRow();
foreach (DataColumn col in data.Columns)
writer.WriteExcelUnstyledCell(col.Caption);
writer.WriteEndRow();
//write data
foreach (DataRow row in data.Rows)
{
writer.WriteStartRow();
foreach (object o in row.ItemArray)
{
writer.WriteExcelAutoStyledCell(o);
}
writer.WriteEndRow();
}
// Close up the document
writer.WriteEndWorksheet();
writer.WriteEndDocument();
writer.Close();
if (openAfter)
OpenFile(fileName);
retry = DialogResult.Cancel;
}
}
catch (Exception myException)
{
retry = MessageBox.Show(myException.Message, "Excel Export", MessageBoxButtons.RetryCancel, MessageBoxIcon.Asterisk);
}
}
}

The following site demonstrates how to export a DataSet (or DataTable or List<>) into a "genuine" Excel 2007 .xlsx file.
It uses the OpenXML libraries, so you don't need to have Excel installed on your server.
C# ExportToExcel library
All of the source code is provided, free of charge, along with instructions using it with ASP.NET, ASP.NET Core 2+ or regular C#.
It's very easy to add to your own applications, you just need to call one function, passing in an Excel filename, and your data source:
DataSet ds = CreateSampleData();
string excelFilename = "C:\\Sample.xlsx";
CreateExcelFile.CreateExcelDocument(ds, excelFilename);
Hope this helps.

Creating excel files in .NET applications is quite common and similar questions have been asked several times before. For instance here and here. The last question asks about reading excel files, but most suggested solutions should work both ways.

This was a post with a really helpful top answer, but I found it was lacking because there was no simple way to import the XML file back into a datatable. I ended up having to write my own, and thought I would share it here in case anyone else was in the same boat (google was exceptionally unhelpful in that regard):
public static DataTable ImportExcelXML(string Filename)
{
//create a new dataset to load in the XML file
DataSet DS = new DataSet();
//Read the XML file into the dataset
DS.ReadXml(Filename);
//Create a new datatable to store the raw Data
DataTable Raw = new DataTable();
//assign the raw data from the file to the datatable
Raw = DS.Tables["Data"];
//count the number of columns in the XML file
int ColumnNumber = Raw.Columns.Count;
//create a datatable to store formatted Import Data
DataTable ImportData = new DataTable();
//create a string list to store the cell data of each row
List<string> RowData = new List<string>();
//loop through each row in the raw data table
for (int Counter = 0; Counter < Raw.Rows.Count; Counter++)
{
//if the data in the row is a colum header
if (Counter < ColumnNumber)
{
//add the column name to our formatted datatable
ImportData.Columns.Add(Raw.Rows[Counter].ItemArray.GetValue(1).ToString());
}
else
{
//if the row # (1 row = 1 cell from the excel file) from the raw datatable is divisable evenly by the number of columns in the formated import datatable AND this is not the 1st row of the raw table data after the headers
if ((Counter % ColumnNumber == 0) && (Counter != ColumnNumber))
{
//add the row we just built to the formatted import datatable
ImportData.Rows.Add(GenerateRow(ImportData, RowData));
//clear rowdata list in preperation for the next row
RowData.Clear();
}
//add the current cell data value from the raw datatable to the string list of cell values for the next row to be added to the formatted input datatable
RowData.Add(Raw.Rows[Counter].ItemArray.GetValue(1).ToString());
}
}
//add the final row
ImportData.Rows.Add(GenerateRow(ImportData, RowData));
return ImportData;
}
public static DataRow GenerateRow(DataTable ImportData, List<string> RowData)
{
//create a counter to keep track of the column position during row composition
int ColumnPosition = 0;
//make a new datarow based on the schema of the formated import datatable
DataRow NewRow = ImportData.NewRow();
//for each string cell value collected for the RowData list for this row
foreach (string CellData in RowData)
{
//add the cell value to the new datarow
NewRow[ImportData.Columns[ColumnPosition].ColumnName] = CellData;
//incriment column position in the new row
ColumnPosition++;
}
//return the generated row
return NewRow;
}

the code have problem with null values.
public void WriteExcelAutoStyledCell(object value)
{
//solve null values
if (value is DBNull) return;

I would have added this to the comments but I am new to stack so I am unable to comment. Using lc.'s solution I added another function that tests the strings characters for invalid XML characters. When I was exporting to excel on occasion there were characters that were found that were causing the export to fail.
You will need to modify one of the functions that is in lc's code.
public void WriteExcelAutoStyledCell(object value)
{
if (_writer == null) throw new InvalidOperationException("Cannot write after closing.");
string newValue = string.Empty;
try
{
//write the <ss:Cell> and <ss:Data> tags for something
if (value is Int16 || value is Int32 || value is Int64 || value is SByte ||
value is UInt16 || value is UInt32 || value is UInt64 || value is Byte)
{
WriteExcelStyledCell(value, CellStyle.Number);
}
else if (value is Single || value is Double || value is Decimal) //we'll assume it's a currency
{
WriteExcelStyledCell(value, CellStyle.Currency);
}
else if (value is DateTime)
{
//check if there's no time information and use the appropriate style
WriteExcelStyledCell(value, ((DateTime)value).TimeOfDay.CompareTo(new TimeSpan(0, 0, 0, 0, 0)) == 0 ? CellStyle.ShortDate : CellStyle.DateTime);
}
else
{
newValue = CheckXmlCompatibleValues(value.ToString()).ToString();
WriteExcelStyledCell(newValue, CellStyle.General);
}
}
catch (Exception thisException)
{
throw new InvalidOperationException(thisException.Message.ToString());
}
}
And add this function to 'ExcelWriter' class
public string CheckXmlCompatibleValues(string value)
{
string newValue = string.Empty;
bool found = false;
foreach (char c in value)
{
if (XmlConvert.IsXmlChar(c))
newValue += c.ToString();
else
found = true;
}
return newValue.ToString();
}
lc. Thanks for the code!

using XL = Microsoft.Office.Interop.Excel;
using System.Reflection;
public static void Datasource(DataTable dt)
{
XL.Application oXL;
XL._Workbook oWB;
XL._Worksheet oSheet;
XL.Range oRng;
try
{
oXL = new XL.Application();
Application.DoEvents();
oXL.Visible = false;
//Get a new workbook.
oWB = (XL._Workbook)(oXL.Workbooks.Add(Missing.Value));
oSheet = (XL._Worksheet)oWB.ActiveSheet;
//System.Data.DataTable dtGridData=ds.Tables[0];
int iRow = 2;
if (dt.Rows.Count > 0)
{
for (int j = 0; j < dt.Columns.Count; j++)
{
oSheet.Cells[1, j + 1] = dt.Columns[j].ColumnName;
}
// For each row, print the values of each column.
for (int rowNo = 0; rowNo < dt.Rows.Count; rowNo++)
{
for (int colNo = 0; colNo < dt.Columns.Count; colNo++)
{
oSheet.Cells[iRow, colNo + 1] = dt.Rows[rowNo][colNo].ToString();
}
iRow++;
}
iRow++;
}
oRng = oSheet.get_Range("A1", "IV1");
oRng.EntireColumn.AutoFit();
oXL.Visible = true;
}
catch (Exception theException)
{
throw theException;
}
finally
{
oXL = null;
oWB = null;
oSheet = null;
oRng = null;
}
}
Import from Excel to datatable:
DataTable dtTable = new DataTable();
DataColumn col = new DataColumn("Rfid");
dtTable.Columns.Add(col);
DataRow drRow;
Microsoft.Office.Interop.Excel.Application ExcelObj =
new Microsoft.Office.Interop.Excel.Application();
Microsoft.Office.Interop.Excel.Workbook theWorkbook =
ExcelObj.Workbooks.Open(txt_FilePath.Text, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
Microsoft.Office.Interop.Excel.Sheets sheets = theWorkbook.Worksheets;
try
{
for (int sht = 1; sht <= sheets.Count; sht++)
{
Microsoft.Office.Interop.Excel.Worksheet worksheet =
(Microsoft.Office.Interop.Excel.Worksheet)sheets.get_Item(sht);
for (int i = 2; i <= worksheet.UsedRange.Rows.Count; i++)
{
Microsoft.Office.Interop.Excel.Range range = worksheet.get_Range("A" + i.ToString(), "B" + i.ToString());
System.Array myvalues = (System.Array)range.Cells.Value2;
String name = Convert.ToString(myvalues.GetValue(1, 1));
if (string.IsNullOrEmpty(name) == false)
{
drRow = dtTable.NewRow();
drRow["Rfid"] = name;
dtTable.Rows.Add(drRow);
}
}
Marshal.ReleaseComObject(worksheet);
worksheet = null;
}
return dtTable;
}
catch
{
throw;
}
finally
{
// Marshal.ReleaseComObject(worksheet);
Marshal.ReleaseComObject(sheets);
Marshal.ReleaseComObject(theWorkbook);
Marshal.ReleaseComObject(ExcelObj);
//worksheet = null;
sheets = null;
theWorkbook = null;
ExcelObj = null;
}

Microsoft has a built in solution for Importing/Exporting Excel files. It's not the most straightforward library but it generally works better than the others listed above.
The library required to do this is included in Office and can be found under the list of Framework assemblies at Microsoft.Office.Interop.Excel.
Here is some example code:
using Excel = Microsoft.Office.Interop.Excel;
Excel.Application app = new Excel.Application();
//Open existing workbook
//Excel.Workbook workbook = xlApp.Workbooks.Open(fileName);
//Create new workbook
Excel.Workbook workbook = app.Workbooks.Add();
Excel.Worksheet worksheet = workbook.ActiveSheet;
worksheet.Cells[1,1] = "Hello world!"; // Indexes start at 1, because Excel
workbook.SaveAs("C:\\MyWorkbook.xlsx");
workbook.Close();
app.Quit();