How do I create an Excel (.XLS and .XLSX) file in C# without installing Microsoft Office?

Question

How can I create an Excel spreadsheet with C# without requiring Excel to be installed on the machine that's running the code?

user_114029 · Answer

I've used with success the following open source projects:

ExcelPackage for OOXML formats (Office 2007)
NPOI for .XLS format (Office 2003). NPOI 2.0 (Beta) also supports XLSX.

Take a look at my blog posts:

Creating Excel spreadsheets .XLS and .XLSX in C#

NPOI with Excel Table and dynamic Chart

Panos_8049 · Answer

You can use OLEDB to create and manipulate Excel files. Check this: Reading and Writing Excel using OLEDB.

Typical example:

using (OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\temp\test.xls;Extended Properties='Excel 8.0;HDR=Yes'"))
{
  conn.Open();
  OleDbCommand cmd = new OleDbCommand("CREATE TABLE [Sheet1] ([Column1] string, [Column2] string)", conn);
  cmd.ExecuteNonQuery();
}

EDIT - Some more links:

Joe_Erickson_56710 · Answer

The commercial solution, SpreadsheetGear for .NET will do it.

You can see live ASP.NET (C# and VB) samples here and download an evaluation version here.

Disclaimer: I own SpreadsheetGear LLC

Forgotten_Semicolon_1960 · Answer

An extremely lightweight option may be to use HTML tables. Just create head, body, and table tags in a file, and save it as a file with an .xls extension. There are Microsoft specific attributes that you can use to style the output, including formulas.

I realize that you may not be coding this in a web application, but here is an example of the composition of an Excel file via an HTML table. This technique could be used if you were coding a console app, desktop app, or service.

user_98180 · Answer

A few options I have used:

If XLSX is a must: ExcelPackage is a good start but died off when the developer quit working on it. ExML picked up from there and added a few features. ExML isn't a bad option, I'm still using it in a couple of production websites.

For all of my new projects, though, I'm using NPOI, the .NET port of Apache POI. NPOI 2.0 (Alpha) also supports XLSX.

Rich_B_5640 · Answer

You actually might want to check out the interop classes available in C# (e.g. Microsoft.Office.Interop.Excel. You say no OLE (which this isn't), but the interop classes are very easy to use. Check out the C# Documentation here (Interop for Excel starts on page 1072 of the C# PDF).

You might be impressed if you haven't tried them.

Please be warned of Microsoft's stance on this:

Microsoft does not currently recommend, and does not support, Automation of Microsoft Office applications from any unattended, non-interactive client application or component (including ASP, ASP.NET, DCOM, and NT Services), because Office may exhibit unstable behavior and/or deadlock when Office is run in this environment.

Admin · Answer

You can use ExcelXmlWriter.

It works fine.

Sam_Warwick_3873 · Answer

You could consider creating your files using the XML Spreadsheet 2003 format. This is a simple XML format using a well documented schema.

ManiacZX_18148 · Answer

You may want to take a look at GemBox.Spreadsheet.

They have a free version with all features but limited to 150 rows per sheet and 5 sheets per workbook, if that falls within your needs.

I haven't had need to use it myself yet, but does look interesting.

user_1628533 · Answer

Syncfusion Essential XlsIO can do this. It has no dependency on Microsoft office and also has specific support for different platforms.

Code sample:

//Creates a new instance for ExcelEngine.
ExcelEngine excelEngine = new ExcelEngine();
//Loads or open an existing workbook through Open method of IWorkbooks
IWorkbook workbook = excelEngine.Excel.Workbooks.Open(fileName);
//To-Do some manipulation|
//To-Do some manipulation
//Set the version of the workbook.
workbook.Version = ExcelVersion.Excel2013;
//Save the workbook in file system as xlsx format
workbook.SaveAs(outputFileName);

The whole suite of controls is available for free through the community license program if you qualify (less than 1 million USD in revenue). Note: I work for Syncfusion.

biozinc_30698 · Answer

The various Office 2003 XML libraries avaliable work pretty well for smaller excel files. However, I find the sheer size of a large workbook saved in the XML format to be a problem. For example, a workbook I work with that would be 40MB in the new (and admittedly more tightly packed) XLSX format becomes a 360MB XML file.

As far as my research has taken me, there are two commercial packages that allow output to the older binary file formats. They are:

Neither are cheap (500USD and 800USD respectively, I think). but both work independant of Excel itself.

What I would be curious about is the Excel output module for the likes of OpenOffice.org. I wonder if they can be ported from Java to .Net.

Evgeny_20336 · Answer

I've just recently used FlexCel.NET and found it to be an excellent library! I don't say that about too many software products. No point in giving the whole sales pitch here, you can read all the features on their website.

It is a commercial product, but you get the full source if you buy it. So I suppose you could compile it into your assembly if you really wanted to. Otherwise it's just one extra assembly to xcopy - no configuration or installation or anything like that.

I don't think you'll find any way to do this without third-party libraries as .NET framework, obviously, does not have built in support for it and OLE Automation is just a whole world of pain.

Slace_11388 · Answer

I agree about generating XML Spreadsheets, here's an example on how to do it for C# 3 (everyone just blogs about it in VB 9 :P) http://www.aaron-powell.com/linq-to-xml-to-excel

MagicKat_8505 · Answer

IKVM + POI

Or, you could use the Interop ...

user_5486 · Answer

Here's a way to do it with LINQ to XML, complete with sample code:

Quickly Import and Export Excel Data with LINQ to XML

It's a little complex, since you have to import namespaces and so forth, but it does let you avoid any external dependencies.

(Also, of course, it's VB .NET, not C#, but you can always isolate the VB .NET stuff in its own project to use XML Literals, and do everything else in C#.)

user_619275 · Answer

Some 3rd party component vendors like Infragistics or Syncfusion provide very good Excel export capabilities that do not require Microsoft Excel to be installed.

Since these vendors also provide advanced UI grid components, these components are particularly handy if you want the style and layout of an excel export to mimic the current state of a grid in the user interface of your application.

If your export is intended to be executed server side with emphasis on the data to be exported and with no link to the UI, then I would go for one of the free open source options (e.g. ExcelLibrary).

I have previously been involved with projects that attempted to use server side automation on the Microsoft Office suite. Based on this experience I would strongly recommend against that approach.

Nick_1490 · Answer

The Java open source solution is Apache POI. Maybe there is a way to setup interop here, but I don't know enough about Java to answer that.

When I explored this problem I ended up using the Interop assemblies.

Splash_25233 · Answer

Have you ever tried sylk?

We used to generate excelsheets in classic asp as sylk and right now we're searching for an excelgenerater too.

The advantages for sylk are, you can format the cells.

user_1847554 · Answer

You can try my SwiftExcel library. This library writes directly to the file, so it is very efficient. For example you can write 100k rows in few seconds without any memory usage.

Here is a simple example of usage:

using (var ew = new ExcelWriter("C:\temp\test.xlsx"))
{
    for (var row = 1; row <= 10; row++)
    {
        for (var col = 1; col <= 5; col++)
        {
            ew.Write($"row:{row}-col:{col}", col, row);
        }
    }
}

user_379972 · Answer

http://www.codeproject.com/KB/cs/Excel_and_C_.aspx <= why not just use the built in power of windows, just install office on the server, any application that you install can be automated.

So much easier just use the native methods.

If it installed you can use it, this is the most awesome and under used feature in windows it was Dubbed COM back in the good old days, and it saves you tons of time and pain.

Or even easier just use the ref lib MS supplies - http://csharp.net-informations.com/excel/csharp-create-excel.htm

user_2917277 · Answer

How to create an Excel (.xslx) file using C# on OneDrive without installing Microsoft Office

The Microsoft Graph API provides File and Excel APIs for creating and modifying Excel files stored in OneDrive for both enterprise and consumer accounts. The Microsoft.Graph NuGet package provides many interfaces for working with the File and Excel APIs.

{
  Name = "myExcelFile.xslx",
  File = new Microsoft.Graph.File()
};

// Create an empty file in the user's OneDrive.
var excelWorkbookDriveItem = await graphClient.Me.Drive.Root.Children.Request().AddAsync(excelWorkbook);

// Add the contents of a template Excel file.
DriveItem excelDriveItem;
using (Stream ms = ResourceHelper.GetResourceAsStream(ResourceHelper.ExcelTestResource))
{
    //Upload content to the file. ExcelTestResource is an empty template Excel file.
    //https://graph.microsoft.io/en-us/docs/api-reference/v1.0/api/item_uploadcontent
    excelDriveItem = await graphClient.Me.Drive.Items[excelWorkbookDriveItem.Id].Content.Request().PutAsync(ms);
}

At this point, you now have an Excel file created in the user (enterprise or consumer) or group's OneDrive. You can now use the Excel APIs to make changes to the Excel file without using Excel and without needing to understand the Excel XML format.

user_6227493 · Answer

I recode again the code and now you can create an .xls file, later you can convert to Excel 2003 Open XML Format.

private static void exportToExcel(DataSet source, string fileName)
    {
        // Documentacion en:
        // https://en.wikipedia.org/wiki/Microsoft_Office_XML_formats
        // https://answers.microsoft.com/en-us/msoffice/forum/all/how-to-save-office-ms-xml-as-xlsx-file/4a77dae5-6855-457d-8359-e7b537beb1db
        // https://riptutorial.com/es/openxml

        const string startExcelXML = "
"+
                 "
" +
                 "
 " +
                 "xmlns:html=\"https://www.w3.org/TR/html401/\">
 " +

                 "
 " +
                 "  16.00
 " +
                 "
 " +
                 " 
 " +
                 "  
 " +
                 " 
 " +

                 " 
 " +
                 "  9750
 " +
                 "  24000
 " +
                 "  0
 " +
                 "  0
 " +
                 "  
 " +
                 "  False
 " +
                 "  False
 " +
                 " 
 " +

                 "
 " +
                 "
 " +
                 "
 " +
                 "
 
 " +
                 "
 
 " +
                 "
 ";
        System.IO.StreamWriter excelDoc = null;
        excelDoc = new System.IO.StreamWriter(fileName,false);

        int sheetCount = 1;
        excelDoc.Write(startExcelXML);
        foreach (DataTable table in source.Tables)
        {
            int rowCount = 0;
            excelDoc.Write("");
            excelDoc.Write("");
            excelDoc.Write("");
            for (int x = 0; x < table.Columns.Count; x++)
            {
                excelDoc.Write("");
                excelDoc.Write(table.Columns[x].ColumnName);
                excelDoc.Write("");
            }
            excelDoc.Write("");
            foreach (DataRow x in table.Rows)
            {
                rowCount++;
                //if the number of rows is > 64000 create a new page to continue output
                if (rowCount == 1048576)
                {
                    rowCount = 0;
                    sheetCount++;
                    excelDoc.Write("");
                    excelDoc.Write(" ");
                    excelDoc.Write("");
                    excelDoc.Write("");
                }
                excelDoc.Write(""); //ID=" + rowCount + "
                for (int y = 0; y < table.Columns.Count; y++)
                {
                    System.Type rowType;
                    rowType = x[y].GetType();
                    switch (rowType.ToString())
                    {
                        case "System.String":
                            string XMLstring = x[y].ToString();
                            XMLstring = XMLstring.Trim();
                            XMLstring = XMLstring.Replace("&", "&");
                            XMLstring = XMLstring.Replace(">", ">");
                            XMLstring = XMLstring.Replace("<", "<");
                            excelDoc.Write("" +
                                           "");
                            excelDoc.Write(XMLstring);
                            excelDoc.Write("");
                            break;
                        case "System.DateTime":
                            //Excel has a specific Date Format of YYYY-MM-DD followed by  
                            //the letter 'T' then hh:mm:sss.lll Example 2005-01-31T24:01:21.000
                            //The Following Code puts the date stored in XMLDate 
                            //to the format above
                            DateTime XMLDate = (DateTime)x[y];
                            string XMLDatetoString = ""; //Excel Converted Date
                            XMLDatetoString = XMLDate.Year.ToString() +
                                 "-" +
                                 (XMLDate.Month < 10 ? "0" +
                                 XMLDate.Month.ToString() : XMLDate.Month.ToString()) +
                                 "-" +
                                 (XMLDate.Day < 10 ? "0" +
                                 XMLDate.Day.ToString() : XMLDate.Day.ToString()) +
                                 "T" +
                                 (XMLDate.Hour < 10 ? "0" +
                                 XMLDate.Hour.ToString() : XMLDate.Hour.ToString()) +
                                 ":" +
                                 (XMLDate.Minute < 10 ? "0" +
                                 XMLDate.Minute.ToString() : XMLDate.Minute.ToString()) +
                                 ":" +
                                 (XMLDate.Second < 10 ? "0" +
                                 XMLDate.Second.ToString() : XMLDate.Second.ToString()) +
                                 ".000";
                            excelDoc.Write("" +
                                         "");
                            excelDoc.Write(XMLDatetoString);
                            excelDoc.Write("");
                            break;
                        case "System.Boolean":
                            excelDoc.Write("" +
                                        "");
                            excelDoc.Write(x[y].ToString());
                            excelDoc.Write("");
                            break;
                        case "System.Int16":
                        case "System.Int32":
                        case "System.Int64":
                        case "System.Byte":
                            excelDoc.Write("" +
                                    "");
                            excelDoc.Write(x[y].ToString());
                            excelDoc.Write("");
                            break;
                        case "System.Decimal":
                        case "System.Double":
                            excelDoc.Write("" +
                                  "");
                            excelDoc.Write(x[y].ToString());
                            excelDoc.Write("");
                            break;
                        case "System.DBNull":
                            excelDoc.Write("" +
                                  "");
                            excelDoc.Write("");
                            excelDoc.Write("");
                            break;
                        default:
                            throw (new Exception(rowType.ToString() + " not handled."));
                    }
                }
                excelDoc.Write("");
            }
            excelDoc.Write("");
            excelDoc.Write("");               
            sheetCount++;
        }

        const string endExcelOptions1 = "

" +
            "
" +
            "False
" +
            "False
" +
            "
";

        excelDoc.Write(endExcelOptions1);
        excelDoc.Write("");
        excelDoc.Close();
    }

user_13794189 · Answer

You can install OpenXml nuget package on Visual Studio. Here is a bit of code to export a data table to an excel file:

Imports DocumentFormat.OpenXml
Imports DocumentFormat.OpenXml.Packaging
Imports DocumentFormat.OpenXml.Spreadsheet

Public Class ExportExcelClass
    Public Sub New()

    End Sub

    Public Sub ExportDataTable(ByVal table As DataTable, ByVal exportFile As String)
        ' Create a spreadsheet document by supplying the filepath.
        ' By default, AutoSave = true, Editable = true, and Type = xlsx.
        Dim spreadsheetDocument As SpreadsheetDocument = spreadsheetDocument.Create(exportFile, SpreadsheetDocumentType.Workbook)

        ' Add a WorkbookPart to the document.
        Dim workbook As WorkbookPart = spreadsheetDocument.AddWorkbookPart
        workbook.Workbook = New Workbook

        ' Add a WorksheetPart to the WorkbookPart.
        Dim Worksheet As WorksheetPart = workbook.AddNewPart(Of WorksheetPart)()
        Worksheet.Worksheet = New Worksheet(New SheetData())

        ' Add Sheets to the Workbook.
        Dim sheets As Sheets = spreadsheetDocument.WorkbookPart.Workbook.AppendChild(Of Sheets)(New Sheets())

        Dim data As SheetData = Worksheet.Worksheet.GetFirstChild(Of SheetData)()
        Dim Header As Row = New Row()
        Header.RowIndex = CType(1, UInt32)

        For Each column As DataColumn In table.Columns
            Dim headerCell As Cell = createTextCell(table.Columns.IndexOf(column) + 1, 1, column.ColumnName)
            Header.AppendChild(headerCell)
        Next

        data.AppendChild(Header)

        Dim contentRow As DataRow
        For i As Integer = 0 To table.Rows.Count - 1
            contentRow = table.Rows(i)
            data.AppendChild(createContentRow(contentRow, i + 2))
        Next

    End Sub

    Private Function createTextCell(ByVal columnIndex As Integer, ByVal rowIndex As Integer, ByVal cellValue As Object) As Cell
        Dim cell As Cell = New Cell()
        cell.DataType = CellValues.InlineString

        cell.CellReference = getColumnName(columnIndex) + rowIndex.ToString

        Dim inlineString As InlineString = New InlineString()
        Dim t As Text = New Text()
        t.Text = cellValue.ToString()
        inlineString.AppendChild(t)
        cell.AppendChild(inlineString)
        Return cell
    End Function

    Private Function createContentRow(ByVal dataRow As DataRow, ByVal rowIndex As Integer) As Row
        Dim row As Row = New Row With {
            .rowIndex = CType(rowIndex, UInt32)
        }

        For i As Integer = 0 To dataRow.Table.Columns.Count - 1
            Dim dataCell As Cell = createTextCell(i + 1, rowIndex, dataRow(i))
            row.AppendChild(dataCell)
        Next

        Return row
    End Function

    Private Function getColumnName(ByVal columnIndex As Integer) As String
        Dim dividend As Integer = columnIndex
        Dim columnName As String = String.Empty
        Dim modifier As Integer

        While dividend > 0
            modifier = (dividend - 1) Mod 26
            columnName = Convert.ToChar(65 + modifier).ToString() & columnName
            dividend = CInt(((dividend - modifier) / 26))
        End While

        Return columnName
    End Function
End Class

user_4216714 · Answer

Some time ago, I created a DLL on top of NPOI. It's very simple to use it:

IList dummyPeople = new List();
//Add data to dummyPeople...
IExportEngine engine = new ExcelExportEngine();
engine.AddData(dummyPeople); 
MemoryStream memory = engine.Export();

You could read more about it on here.

By the way, is 100% open source. Feel free to use, edit and share ;)

user_3433702 · Answer

To save xls into xlsx format, we just need to call SaveAs method from Microsoft.Office.Interop.Excel library. This method will take around 16 parameters and one of them is file format as well.

Microsoft document: Here SaveAs Method Arguments

The object we need to pass is like

wb.SaveAs(filename, 51, System.Reflection.Missing.Value,
System.Reflection.Missing.Value, false, false, 1,1, true, 
System.Reflection.Missing.Value, System.Reflection.Missing.Value, System.Reflection.Missing.Value)

Here, 51 is is enumeration value for XLSX

For SaveAs in different file formats you can refer the xlFileFormat

user_2785361 · Answer

I wonder why nobody suggested PowerShell with the free ImportExcel Module; it creates XML-Excel files (xlsx) with ease.

Especially easy when creating Excel-sheets coming from Databases like SQL Server...

user_1084742 · Answer

In my projects, I use some several .net libraries to extract Excel File (both .xls and .xlsx)

To Export data, I frequently use rdlc.

To modify excel files I use (Sample code when I try to set blank Cell A15):

ClosedXML

        //Closed XML
        var workbook = new XLWorkbook(sUrlFile); // load the existing excel file
        var worksheet = workbook.Worksheets.Worksheet(1);
        worksheet.Cell("A15").SetValue("");
        workbook.Save();

IronXL

       string sUrlFile = "G:\ReportAmortizedDetail.xls";
        WorkBook workbook = WorkBook.Load(sUrlFile);
        WorkSheet sheet = workbook.WorkSheets.First();
        //Select cells easily in Excel notation and return the calculated value
        sheet["A15"].First().Value = "";
        sheet["A15"].First().FormatString = "";

        workbook.Save();
        workbook.Close();
        workbook = null;

SpireXLS (When I try, the library print additional sheet to give information that we use the trial library

            string sUrlFile = "G:\ReportAmortizedDetail.xls";
            Workbook workbook = new Workbook();
            workbook.LoadFromFile(sUrlFile);
            //Get the 1st sheet
            Worksheet sheet = workbook.Worksheets[0];
            //Specify the cell range
            CellRange range = sheet.Range["A15"];
            //Find all matched text in the range
            CellRange[] cells = range.FindAllString("hi", false, false);
            //Replace text
            foreach (CellRange cell in range)
            {
                cell.Text = "";
            }
            //Save
            workbook.Save();

Jet Oledb

    //ExcelTool Class
    public static int ExcelUpdateSheets(string path, string sWorksheetName, string sCellLocation, string sValue)
    {
        int iResult = -99;
        String sConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path + ";Extended Properties='Excel 8.0;HDR=NO'";
        OleDbConnection objConn = new OleDbConnection(sConnectionString);
        objConn.Open();
        OleDbCommand objCmdSelect = new OleDbCommand("UPDATE [" + sWorksheetName + "$" + sCellLocation + "] SET F1=" + UtilityClass.ValueSQL(sValue), objConn);
        objCmdSelect.ExecuteNonQuery();
        objConn.Close();

        return iResult;
    }

Usage :

    ExcelTool.ExcelUpdateSheets(sUrlFile, "ReportAmortizedDetail", "A15:A15", "");

Aspose

            var workbook = new Aspose.Cells.Workbook(sUrlFile);
            // access first (default) worksheet
            var sheet = workbook.Worksheets[0];
            // access CellsCollection of first worksheet
            var cells = sheet.Cells;
            // write HelloWorld to cells A1
            cells["A15"].Value = "";
            // save spreadsheet to disc
            workbook.Save(sUrlFile);
            workbook.Dispose();
            workbook = null;

user_10186832 · Answer

Here is the simplest way to create an Excel file.

Excel files with extension .xlsx are compressed folders containing .XML files - but complicated.

First create the folder structure as follows -

public class CreateFileOrFolder
{
    static void Main()
    {
        //
        // https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/file-system/how-to-create-a-file-or-folder
        //
        // https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/file-system/how-to-write-to-a-text-file
        //
        // .NET Framework 4.7.2
        //
        // Specify a name for your top-level folder.
        string folderName = @"C:\Users\david\Desktop\Book3";

        // To create a string that specifies the path to a subfolder under your
        // top-level folder, add a name for the subfolder to folderName.

        string pathString = System.IO.Path.Combine(folderName, "_rels");
        System.IO.Directory.CreateDirectory(pathString);
        pathString = System.IO.Path.Combine(folderName, "docProps");
        System.IO.Directory.CreateDirectory(pathString);
        pathString = System.IO.Path.Combine(folderName, "xl");
        System.IO.Directory.CreateDirectory(pathString);

        string subPathString = System.IO.Path.Combine(pathString, "_rels");
        System.IO.Directory.CreateDirectory(subPathString);
        subPathString = System.IO.Path.Combine(pathString, "theme");
        System.IO.Directory.CreateDirectory(subPathString);
        subPathString = System.IO.Path.Combine(pathString, "worksheets");
        System.IO.Directory.CreateDirectory(subPathString);
        // Keep the console window open in debug mode.
        System.Console.WriteLine("Press any key to exit.");
        System.Console.ReadKey();
    }
}

Next, create text files to hold the XML needed to describe the Excel spreadsheet.

namespace MakeFiles3
{
    class Program
    {
        static void Main(string[] args)
        {
            //
            // https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/file-system/how-to-write-to-a-text-file
            //
            // .NET Framework 4.7.2
            //
            string fileName = @"C:\Users\david\Desktop\Book3\_rels\.rels";
            fnWriteFile(fileName);
            fileName = @"C:\Users\david\Desktop\Book3\docProps\app.xml";
            fnWriteFile(fileName);
            fileName = @"C:\Users\david\Desktop\Book3\docProps\core.xml";
            fnWriteFile(fileName);
            fileName = @"C:\Users\david\Desktop\Book3\xl\_rels\workbook.xml.rels";
            fnWriteFile(fileName);
            fileName = @"C:\Users\david\Desktop\Book3\xl\theme\theme1.xml";
            fnWriteFile(fileName);
            fileName = @"C:\Users\david\Desktop\Book3\xl\worksheets\sheet1.xml";
            fnWriteFile(fileName);
            fileName = @"C:\Users\david\Desktop\Book3\xl\styles.xml";
            fnWriteFile(fileName);
            fileName = @"C:\Users\david\Desktop\Book3\xl\workbook.xml";
            fnWriteFile(fileName);
            fileName = @"C:\Users\david\Desktop\Book3\[Content_Types].xml";
            fnWriteFile(fileName);
            // Keep the console window open in debug mode.
            System.Console.WriteLine("Press any key to exit.");
            System.Console.ReadKey();

            bool fnWriteFile(string strFilePath)
            {
                if (!System.IO.File.Exists(strFilePath))
                {
                    using (System.IO.FileStream fs = System.IO.File.Create(strFilePath))
                    {
                        return true;
                    }
                }
                else
                {
                    System.Console.WriteLine("File \"{0}\" already exists.", strFilePath);
                    return false;
                }
            }
        }
    }
}

Next populate the text files with XML.

The XML required is fairly verbose so you may need to use this github repository.

https://github.com/DaveTallett26/MakeFiles4/blob/master/MakeFiles4/Program.cs

//
// https://docs.microsoft.com/en-us/dotnet/standard/io/how-to-write-text-to-a-file
// .NET Framework 4.7.2
//
using System.IO;

namespace MakeFiles4
{
    class Program
    {
        static void Main(string[] args)
        {
            string xContents = @"a";
            string xFilename = @"a";
            xFilename = @"C:\Users\david\Desktop\Book3\[Content_Types].xml";
            xContents = @"";
            StartExstream(xContents, xFilename);

            xFilename = @"C:\Users\david\Desktop\Book3\_rels\.rels";
            xContents = @"";
            StartExstream(xContents, xFilename);

            xFilename = @"C:\Users\david\Desktop\Book3\docProps\app.xml";
            xContents = @"Microsoft Excel0falseWorksheets1Sheet1falsefalsefalse16.0300";
            StartExstream(xContents, xFilename);

            xFilename = @"C:\Users\david\Desktop\Book3\docProps\core.xml";
            xContents = @"David TallettDavid Tallett2021-10-26T15:47:15Z2021-10-26T15:47:35Z";
            StartExstream(xContents, xFilename);

            xFilename = @"C:\Users\david\Desktop\Book3\xl\styles.xml";
            xContents = @"";
            StartExstream(xContents, xFilename);

            xFilename = @"C:\Users\david\Desktop\Book3\xl\workbook.xml";
            xContents = @"";
            StartExstream(xContents, xFilename);

            xFilename = @"C:\Users\david\Desktop\Book3\xl\_rels\workbook.xml.rels";
            xContents = @"";
            StartExstream(xContents, xFilename);

            xFilename = @"C:\Users\david\Desktop\Book3\xl\theme\theme1.xml";
            xContents = @"";
            StartExstream(xContents, xFilename);

            xFilename = @"C:\Users\david\Desktop\Book3\xl\worksheets\sheet1.xml";
            xContents = @"123";
            StartExstream(xContents, xFilename);

            // Keep the console window open in debug mode.
            System.Console.WriteLine("Press any key to exit.");
            System.Console.ReadKey();

            bool StartExstream(string strLine, string strFileName)
            {
                // Write the string to a file.
                using (StreamWriter outputFile = new StreamWriter(strFileName))
                {
                    outputFile.WriteLine(strLine);
                    return true;
                }
            }
        }
    }
}

Finally ZIP the folder structure containing the XML -

namespace ZipFolder
// .NET Framework 4.7.2
// https://stackoverflow.com/questions/15241889/i-didnt-find-zipfile-class-in-the-system-io-compression-namespace?answertab=votes#tab-top
{
    class Program
    {
        static void Main(string[] args)
        {
            string xlPath = @"C:\Users\david\Desktop\Book3.xlsx";
            string folderPath = @"C:\Users\david\Desktop\Book3";

            System.IO.Compression.ZipFile.CreateFromDirectory(folderPath, xlPath);

            // Keep the console window open in debug mode.
            System.Console.WriteLine("Press any key to exit.");
            System.Console.ReadKey();
        }
    }
}

This produces an Excel file named Book3.xlsx which is valid and opens cleanly in Excel 365 on Windows 11.

The result is a very simple Excel spreadsheet but you may need to reverse engineer a more complex version. Here is the code to unzip a .xlsx file.

namespace UnZipXL
// .NET Framework 4.7.2
// https://stackoverflow.com/questions/15241889/i-didnt-find-zipfile-class-in-the-system-io-compression-namespace?answertab=votes#tab-top
{
    class Program
    {
        static void Main(string[] args)
        {
            string XLPath = @"C:\Users\david\Desktop\Book2.xlsx";
            string extractPath = @"C:\Users\david\Desktop\extract";

            System.IO.Compression.ZipFile.ExtractToDirectory(XLPath, extractPath);

            // Keep the console window open in debug mode.
            System.Console.WriteLine("Press any key to exit.");
            System.Console.ReadKey();
        }
    }
}

Update:

Here is a code fragment to update the Excel file. This is very simple again.

//
// https://docs.microsoft.com/en-us/dotnet/standard/io/how-to-write-text-to-a-file
// .NET Framework 4.7.2
//
using System.IO;

namespace UpdateWorksheet5
{
    class Program
    {
        static void Main(string[] args)
        {
            string xContents = @"a";
            string xFilename = @"a";

            xFilename = @"C:\Users\david\Desktop\Book3\xl\worksheets\sheet1.xml";
            xContents = @"123";
            xContents = xContents.Remove(941, 1).Insert(941, "0"); //  character to replace is at 942 => index 941
            StartExstream(xContents, xFilename);

            // Keep the console window open in debug mode.
            System.Console.WriteLine("Press any key to exit.");
            System.Console.ReadKey();

            bool StartExstream(string strLine, string strFileName)
            {
                // Write the string to a file.
                using (StreamWriter outputFile = new StreamWriter(strFileName))
                {
                    outputFile.WriteLine(strLine);
                    return true;
                }
            }
        }
    }
}

Update 2 - This code works almost unchanged except for the folder paths on a Mac. Using Microsoft Excel Online, .NET Framework 3.1, Visual Studio 2019 for Mac, MacOS Monterey 12.1.

user_8743724 · Answer

check this out no need for third party libraries you can simply export datatable data to excel file using this

var dt = "your code for getting data into datatable";
            Response.ClearContent();
            Response.AddHeader("content-disposition", string.Format("attachment;filename={0}.xls", DateTime.Now.ToString("yyyy-MM-dd")));
            Response.ContentType = "application/vnd.ms-excel";
            string tab = "";
            foreach (DataColumn dataColumn in dt.Columns)
            {
                Response.Write(tab + dataColumn.ColumnName);
                tab = "	";
            }
            Response.Write("
");
            int i;
            foreach (DataRow dataRow in dt.Rows)
            {
                tab = "";
                for (i = 0; i < dt.Columns.Count; i++)
                {
                    Response.Write(tab + dataRow[i].ToString());
                    tab = "	";
                }
                Response.Write("
");
            }
            Response.End();

How do I create an Excel (.XLS and .XLSX) file in C# without installing Microsoft Office?

46 Answers

How to create an Excel (.xslx) file using C# on OneDrive without installing Microsoft Office