how to export data into excel

Question

How to export data from datatable into excel file with a proper output. i means first row of excel record should be the header and the display data should show all the value instead of rounding up the values. please help ** ldt_Temp (datatable),as_OutputDir (exported dir)

object misValue = System.Reflection.Missing.Value;
Microsoft.Office.Interop.Excel.Application app = new Microsoft.Office.Interop.Excel.Application();
app.Visible = false;
Microsoft.Office.Interop.Excel.Workbook wb = app.Workbooks.Add(Microsoft.Office.Interop.Excel.XlWBATemplate.xlWBATWorksheet);
Microsoft.Office.Interop.Excel.Worksheet ws = (Microsoft.Office.Interop.Excel.Worksheet)wb.ActiveSheet;
// Headers.  
for (int i = 0; i < ldt_Temp.Columns.Count; i++)
{
    ws.Cells[1, i + 1] = ldt_Temp.Columns[i].ColumnName;
}
// Content.  
for (int i = 0; i < ldt_Temp.Rows.Count; i++)
{
 for (int j = 0; j < ldt_Temp.Columns.Count; j++)
  {
     ws.Cells[i + 2, j + 1] = ldt_Temp.Rows[i][j].ToString();
  }
}
 ws.Name = ldt_Temp.TableName;
 wb.SaveAs(as_OutputDir, Microsoft.Office.Interop.Excel.XlFileFormat.xlWorkbookNormal, misValue, misValue, misValue, misValue, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlExclusive, misValue, misValue, misValue, misValue, misValue);
wb.Close(true, misValue, misValue);
app.Quit();

Answer 1

Row 1 appears to be the header already... your arrow points to the column labels. Are you wanting 'A' to be "Site_Site_id"? That's not how excel works.

For precision, right click and choose format. Now change the decimal precision to what every you want displayed.

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You can also highlight all your cells and used the toolbar buttons:

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You can try to do it in code this way:

// Content.  
for (int i = 0; i < ldt_Temp.Rows.Count; i++)
{
 for (int j = 0; j < ldt_Temp.Columns.Count; j++)
  {
     ws.Cells[i + 2, j + 1] = ldt_Temp.Rows[i][j].ToString();
     ws.Cells[i + 2, j + 1].NumberFormat = "0.00000000000000000"
  }
}

Answer 2

and i also find out a way to rearrange each number format for each cells, loop each cells and get the length of digit and create the format dynamically

 string ls_Test = cells value 
 string part = ls_Test.Substring(0, ls_Test.IndexOf('.'));
 string ls_FormatDeicmal = ls_Test.Substring(part.Length + 1, ls_Test.Length - (part.Length + 1));
 string ls_DigiFormat = "";
 for (int f = 0; f < ls_FormatDeicmal.Length; f++)
 {
     ls_DigiFormat += "0";
 }
 ls_DigiFormat = "0." + ls_DigiFormat; // 0.000000000, 0.00, 0.00000
 ws.Cells[i + 2, j + 1].NumberFormat = ls_DigiFormat;