My Winforms program always creates an instance of Excel (even without using Excel in the program)

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My Winforms program always creates an instance of Excel (even without using Excel in the program)

john noble 181

I have a winforms program. In certain parts of the program there is the ability to export data to Excel. To do this I have added a reference to Microsoft.Office.Interop.Excel. This seems to create an instance of excel that runs in the background (even before I use any of the Excel related programs within the app).

I have noticed that on PCs where MS Office is not installed, having this background instance of Excel running really slows down the performance of the program. It can take up to a minute just to load all the buttons, labels etc on a form. (It takes less than a second normally). As soon as I End the Excel Process in the Task Manager, the program loads up instantly.

Is there anyway I can have a reference to the Microsoft.Office.Interop.Excel without it starting an actual Instance of Excel in the background ?

Regards,

John

Minxin Yu 13,501 Reputation points Microsoft External Staff

2023-04-28T09:18:56.76+00:00

Can you show the relevant code?

Karen Payne MVP 35,586 Volunteer Moderator

Excel automation is inherently slow in the first place. There are other options but not recommending one as I do not what work you are doing as export to Excel is not enough information. Here is what code might look like.

public static void ExportToExcel(DataTable table, string fileName, bool includeHeader, string sheetName)
{
    using var document = new SLDocument();

    // import to first row, first column
    document.ImportDataTable(1, SLConvert.ToColumnIndex("A"), table, includeHeader);

    // give sheet a useful name
    document.RenameWorksheet(SLDocument.DefaultFirstSheetName, sheetName);

    document.SaveAs(fileName);
}

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Minxin Yu 13,501 Reputation points Microsoft External Staff

2023-04-28T09:18:56.76+00:00

Can you show the relevant code?
Karen Payne MVP 35,586 Reputation points Volunteer Moderator

2023-04-28T10:30:01.78+00:00

Excel automation is inherently slow in the first place. There are other options but not recommending one as I do not what work you are doing as export to Excel is not enough information. Here is what code might look like.

public static void ExportToExcel(DataTable table, string fileName, bool includeHeader, string sheetName) { using var document = new SLDocument(); // import to first row, first column document.ImportDataTable(1, SLConvert.ToColumnIndex("A"), table, includeHeader); // give sheet a useful name document.RenameWorksheet(SLDocument.DefaultFirstSheetName, sheetName); document.SaveAs(fileName); }

Answer 1

Bruce (SqlWork.com) 77,686 Volunteer Moderator

don't call:

    var excelApp = new Excel.Application();

until you need it.

Answer 2

Hi folks,

I think I have tracked down the source of the problem....

try
{
     Type officeType = Type.GetTypeFromProgID("Excel.Application");
     dynamic xlApp = Activator.CreateInstance(officeType);
     xlApp.Visible = false;
     pathToExcel = xlApp.Path + @"\Excel.exe";
     xlApp.Quit();
     xlApp.Dispose();
}

In my code, I try and get the path to the Excel exe (as some PCs may have had 32 / 64 bit versions). Once I had the path, I could then just call Start.Process(pathtoExcel). It would seem even calling xlApp.Quit() and xlApp.Dispose() does not kill the process.

But now, I have reconfigured my code so that I dont need to know the path anymore.

Thanks again,

John

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My Winforms program always creates an instance of Excel (even without using Excel in the program)

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