C# - Numbers Are Converted As Text When Export Dataset To Excel

Iam exporting dataset to excel , the numbers on the sheet shown as text when export it to excel. Here is the code:

public class Excel
{
const int rowLimit = 65000;
private static string getWorkbookTemplate()
{
StringBuilder sb = new StringBuilder(818);
sb.AppendFormat(@"<?xml version=""1.0""?>{0}", Environment.NewLine);
sb.AppendFormat(@"<?mso-application progid=""Excel.Sheet""?>{0}", Environment.NewLine);
sb.AppendFormat(@"<Workbook xmlns=""urn:schemas-microsoft-com:office:spreadsheet""{0}", Environment.NewLine);
sb.AppendFormat(@" xmlns:o=""urn:schemas-microsoft-com:office:office""{0}", Environment.NewLine);
sb.AppendFormat(@" xmlns:x=""urn:schemas-microsoft-com:office:excel""{0}", Environment.NewLine);
sb.AppendFormat(@" xmlns:ss=""urn:schemas-microsoft-com:office:spreadsheet""{0}", Environment.NewLine);
sb.AppendFormat(@" xmlns:html=""[URL]
sb.AppendFormat(@" <Styles>{0}", Environment.NewLine);
sb.AppendFormat(@" <Style ss:ID=""Default"" ss:Name=""Normal"">{0}", Environment.NewLine);
sb.AppendFormat(@" <Alignment ss:Vertical=""Bottom""/>{0}", Environment.NewLine);
sb.AppendFormat(@" <Borders/>{0}", Environment.NewLine);
sb.AppendFormat(@" <Font ss:FontName=""Verdana"" x:Family=""Swiss"" ss:Size=""12"" ss:Color=""#0000A0""/>{0}", Environment.NewLine);
sb.AppendFormat(@" <Interior/>{0}", Environment.NewLine);
sb.AppendFormat(@" <NumberFormat/>{0}", Environment.NewLine);
sb.AppendFormat(@" <Protection/>{0}", Environment.NewLine);
sb.AppendFormat(@" </Style>{0}", Environment.NewLine);
sb.AppendFormat(@" <Style ss:ID=""s62"">{0}", Environment.NewLine);
sb.AppendFormat(@" <Font ss:FontName=""Calibri"" x:Family=""Swiss"" ss:Size=""11"" ss:Color=""#000000""{0}", Environment.NewLine);
sb.AppendFormat(@" ss:Bold=""1""/>{0}", Environment.NewLine);
sb.AppendFormat(@" </Style>{0}", Environment.NewLine);
sb.AppendFormat(@" <Style ss:ID=""s63"">{0}", Environment.NewLine);
sb.AppendFormat(@" <NumberFormat ss:Format=""Short Date""/>{0}", Environment.NewLine);
sb.AppendFormat(@" </Style>{0}", Environment.NewLine);
sb.AppendFormat(@" </Styles>{0}", Environment.NewLine);
sb.Append(@"{0}
</Workbook>");
return sb.ToString();
}
private static string replaceXmlChar(string input)
{
input = input.Replace("&", "&");
input = input.Replace("<", "<");
input = input.Replace(">", ">");
input = input.Replace(""", """);
input = input.Replace("'", "&apos;");
return input;
}
private static string getCell(Type type, object cellData)
{
Object data = (cellData is DBNull) ? "" : cellData;
if (type.Name.Contains("Int") || type.Name.Contains("Double") || type.Name.Contains("Decimal")) return string.Format("<Cell><Data ss:Type="Number">{0}</Data></Cell>", data);
if (type.Name.Contains("Date") && data.ToString() != string.Empty)
{
return string.Format("<Cell ss:StyleID="s63"><Data ss:Type="DateTime">{0}</Data></Cell>", Convert.ToDateTime(data).ToString("yyyy-MM-dd"));
}
return string.Format("<Cell><Data ss:Type="String">{0}</Data></Cell>", replaceXmlChar(data.ToString()));
}
private static string getWorksheets(DataSet source)
{
StringWriter sw = new StringWriter();
if (source == null || source.Tables.Count == 0)
{
sw.Write("<Worksheet ss:Name="Sheet1">
<Table>
<Row><Cell><Data ss:Type="String"></Data></Cell></Row>
</Table>
</Worksheet>");
return sw.ToString();
}
foreach (DataTable dt in source.Tables)
{
if (dt.Rows.Count == 0)
sw.Write("<Worksheet ss:Name="" + replaceXmlChar(dt.TableName) + "">
<Table>
<Row><Cell ss:StyleID="s62"><Data ss:Type="String"></Data></Cell></Row>
</Table>
</Worksheet>");
else
{
//write each row data
int sheetCount = 0;
for (int i = 0; i < dt.Rows.Count; i++)
{
if ((i % rowLimit) == 0)
{
//add close tags for previous sheet of the same data table
if ((i / rowLimit) > sheetCount)
{
sw.Write("
</Table>
</Worksheet>");
sheetCount = (i / rowLimit);
}
sw.Write("
<Worksheet ss:Name="" + replaceXmlChar(dt.TableName) +
(((i / rowLimit) == 0) ? "" : Convert.ToString(i / rowLimit)) + "">
<Table>");
//write column name row
sw.Write("
<Row>");
foreach (DataColumn dc in dt.Columns)
sw.Write(string.Format("<Cell ss:StyleID="s62"><Data ss:Type="String">{0}</Data></Cell>", replaceXmlChar(dc.ColumnName)));
sw.Write("</Row>");
}
sw.Write("
<Row>");
foreach (DataColumn dc in dt.Columns)
sw.Write(getCell(dc.DataType, dt.Rows[i][dc.ColumnName]));
sw.Write("</Row>");
}
sw.Write("
</Table>
</Worksheet>");
}
}
return sw.ToString();
}
public static string GetExcelXml(DataTable dtInput, string filename)
{
string excelTemplate = getWorkbookTemplate();
DataSet ds = new DataSet();
ds.Tables.Add(dtInput.Copy());
string worksheets = getWorksheets(ds);
string excelXml = string.Format(excelTemplate, worksheets);
return excelXml;
}
public static string GetExcelXml(DataSet dsInput, string filename)
{
string excelTemplate = getWorkbookTemplate();
string worksheets = getWorksheets(dsInput);
string excelXml = string.Format(excelTemplate, worksheets);
return excelXml;
}
public static void ToExcel(DataSet dsInput, string filename, HttpResponse response)
{
string excelXml = GetExcelXml(dsInput, filename);
response.Clear();
response.AppendHeader("Content-Type", "application/vnd.ms-excel");
response.AppendHeader("Content-disposition", "attachment; filename=" + filename);
response.Write(excelXml);
response.Flush();
response.End();
}
public static void ToExcel(DataTable dtInput, string filename, HttpResponse response)
{
DataSet ds = new DataSet();
ds.Tables.Add(dtInput.Copy());
ToExcel(ds, filename, response);
}
}