Cannot convert type double to string // Excel numbers are double?

Question

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Trying to add the cell's data to an ArrayList but keep getting 'Cannot convert type Double To String'.

The value in the cell is '1' and the type is general. When I pulled in the headers in the workbook, they all worked.

[Edit1]While I was typing I changed (duh)

C#

col1.Add((string)(ws.Cells[currentRow, "A"] as Excel1.Range).Value2);

TO

C#

col1.Add((double)(ws.Cells[currentRow, "A"] as Excel1.Range).Value2);

and everything works now.

So my question now is, are all numbers from excel doubles?

[Edit2]I looked in Task Manager and there are a whole lot of Excel.exe's open, how do I close them?

C#

public void ReadSheet()
		{
			try
			{
				Excel1.Application app = new Excel1.Application();
				Excel1.Workbook wb = app.Workbooks.Open(this.txtBoxFile.Text, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
				Excel1.Sheets sheets = wb.Worksheets;
				Excel1.Worksheet ws = (Excel1.Worksheet)sheets[1];
				int currentRow = 2;
				while ((ws.Cells[currentRow, "A"] as Excel1.Range).Value2 != null && (ws.Cells[currentRow, "B"] as Excel1.Range).Value2 != null)
				{
					MessageBox.Show("1");
					col1.Add((string)(ws.Cells[currentRow, "A"] as Excel1.Range).Value2);
					col2.Add((string)(ws.Cells[currentRow, "B"] as Excel1.Range).Value2);
					col3.Add((string)(ws.Cells[currentRow, "C"] as Excel1.Range).Value2);
					col4.Add((string)(ws.Cells[currentRow, "D"] as Excel1.Range).Value2);
					MessageBox.Show("2");
					currentRow++;
				}
				GC.Collect();
				GC.WaitForPendingFinalizers();
				
				Marshal.FinalReleaseComObject(ws);
				Marshal.FinalReleaseComObject(sheets);
				
				wb.Close(false, Type.Missing, Type.Missing);
				Marshal.FinalReleaseComObject(wb);
				
				app.Quit();
				Marshal.FinalReleaseComObject(app);
			}
			catch(InvalidCastException ic)
			{
				MessageBox.Show(ic.Message, "CastException");
			}
			catch (Exception e)
			{
				MessageBox.Show(e.Message, "Exception");
			}
			finally
			{
				//
				ExcelToTxt();
			}
		}

Posted 24-Oct-11 0:20am

M Bester

Updated 24-Oct-11 0:23am

v2

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2 solutions

Solution 2

To close excel completely, you have to close all COM objects.

C#

public void CloseXLS(String savedFileName)
{
    // Cleanup
    GC.Collect();
    GC.WaitForPendingFinalizers();

    Marshal.FinalReleaseComObject(objectRng);
    Marshal.FinalReleaseComObject(worksheet);

    workbook.Close(true, savedFileName, Type.Missing);
    Marshal.FinalReleaseComObject(workbook);

    app.Quit();
    Marshal.FinalReleaseComObject(app);
}

Where objectRng is a Range object, and app is the excel instance.
If possible do not use process kills.

Posted 3-Aug-12 4:18am

Zsombi55

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Menon Santosh · Accepted Answer · 2011-10-24T00:36:00

use this code to kill the instance of excel

C#

[DllImport("user32")]
private static extern IntPtr GetWindowThreadProcessId(int hWnd,ref IntPtr lpdwProcessId);

private void KillProcess(Microsoft.Office.Interop.Excel.Application exl)
{
    IntPtr processId = new IntPtr();
    GetWindowThreadProcessId(exl.Hwnd,ref processId);
    Process excelProcess = Process.GetProcessById(processId.ToInt32());
    excelProcess.Kill();
    

}