C#

if (Excelpfad == "")
    return false;

Microsoft.Office.Interop.Excel.Application excelApp = new Microsoft.Office.Interop.Excel.ApplicationClass();
Microsoft.Office.Interop.Excel.Workbook newWorkbook = excelApp.Workbooks.Add(Microsoft.Office.Interop.Excel.XlWBATemplate.xlWBATWorksheet);
Microsoft.Office.Interop.Excel.Sheets excelSheets = newWorkbook.Worksheets;
string currentSheet = "Tabelle1";
Microsoft.Office.Interop.Excel.Worksheet worksheet = (Microsoft.Office.Interop.Excel.Worksheet)excelSheets.get_Item(currentSheet);

for (int i = 0; i < UsingGrid.Cols; i++)
{
    for (int j = 0; j < UsingGrid.Rows; j++)
    {
        worksheet.Cells[j + 1, i + 1] = Convert.ToString(UsingGrid[j, i]);
    }
}

// Autosize cols
for (int iExcel = 0; iExcel < UsingGrid.Cols; iExcel++)
{
    ((Microsoft.Office.Interop.Excel.Range)worksheet.Columns[iExcel + 1, t]).ColumnWidth = UsingGrid.get_ColWidth(iExcel) * 0.13171875;
}

if (Excelpfad.Substring(Excelpfad.LastIndexOf(".")) == ".xls")
    worksheet.SaveAs(Excelpfad, Microsoft.Office.Interop.Excel.XlFileFormat.xlExcel8, t, t, t, t, t, t, t, t);
else if (Excelpfad.Substring(Excelpfad.LastIndexOf(".")) == ".xlsx")
    worksheet.SaveAs(Excelpfad, t, t, t, t, t, t, t, t, t);

newWorkbook.Close(true, n, n);
excelApp.Quit();
System.Runtime.InteropServices.Marshal.ReleaseComObject(worksheet);