excel - C# - convert xls file to xlsx without office components

Question

I have a server that can't have any office installed on it, so I'm using ClosedXML to do some manipulations on excel files. But ClosedXML only works on .xlsx file and I also have xls file to handle. I spend almost a full day searching for a way to convert .xls files to .xlsx files without using any office libraries (since there is no office installed on my designated server...)

Can someone PLEASE tell me how can I convert these .xls files to .xlsx files ? I can't use Microsoft.Office.Interop because it requires having office installed on the server.

Answer 1

For Microsoft.Office.Interop you need to have office installed.

You could use OleDb to read it(f.e. into a DataTable). Then use a library like EPPlus or OpenXml to write the xlsx file. Both don't need to have office installed.

Creating an xlsx file from a DataTable with EPPLus is easy:

using (ExcelPackage pck = new ExcelPackage(newFile))
{
  ExcelWorksheet ws = pck.Workbook.Worksheets.Add("Name of Worksheet");
  ws.Cells["A1"].LoadFromDataTable(dataTable, true);
  pck.Save();
}

The first link above shows how to get a DataTable from an xls-file.