Writing Data to an Existing Excel File in C#

Question

I want to write data to an existing Excel file, whilst preserving the original data.

The file has sheet1; I want to write on sheet2, then save. The problem is that e

Answer 1

According to Programmatically Insert to Existing Excel File using C# by R Manimaran:

Here is the code which will do the insertion in an already exists excel file.

private static Microsoft.Office.Interop.Excel.Workbook mWorkBook;
private static Microsoft.Office.Interop.Excel.Sheets mWorkSheets;
private static Microsoft.Office.Interop.Excel.Worksheet mWSheet1;
private static Microsoft.Office.Interop.Excel.Application oXL;
public static void ReadExistingExcel()
{
   string path = @"C:\Tool\Reports1.xls";
   oXL = new Microsoft.Office.Interop.Excel.Application();
   oXL.Visible = true;
   oXL.DisplayAlerts = false;
   mWorkBook = oXL.Workbooks.Open(path, 0, false, 5, "", "", false, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "", true, false, 0, true, false, false);
   //Get all the sheets in the workbook
  mWorkSheets = mWorkBook.Worksheets;
   //Get the allready exists sheet
   mWSheet1 = (Microsoft.Office.Interop.Excel.Worksheet)mWorkSheets.get_Item("Sheet1");
   Microsoft.Office.Interop.Excel.Range range= mWSheet1.UsedRange;
   int colCount = range.Columns.Count;
   int rowCount= range.Rows.Count;
   for (int index = 1; index < 15; index++)
   {
      mWSheet1.Cells[rowCount + index, 1] = rowCount +index;
      mWSheet1.Cells[rowCount + index, 2] = "New Item"+index;
   }
   mWorkBook.SaveAs(path, Microsoft.Office.Interop.Excel.XlFileFormat.xlWorkbookNormal,
   Missing.Value, Missing.Value, Missing.Value,    Missing.Value,Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlExclusive,
   Missing.Value, Missing.Value, Missing.Value,
   Missing.Value, Missing.Value);
   mWorkBook.Close(Missing.Value, Missing.Value, Missing.Value);
   mWSheet1 = null;
   mWorkBook = null;
   oXL.Quit();
   GC.WaitForPendingFinalizers();
   GC.Collect();
   GC.WaitForPendingFinalizers();
   GC.Collect();
} 

If you need to create a new Sheet use the following code.

oSheet = (Excel.Worksheet)oWB.Sheets.Add(Missing.Value, Missing.Value, Missing.Value,      Missing.Value);

oSheet.Name = SheetName;