Changing the formatting of an Excel cell with NPOI

We use NPOI to generate Excel files. The old format for negative numbers was to have parentheses around them, but a new requirement was to instead use a minus sign.

The way we handle cell formatting is a custom function, GetCellStyle, that returns the new DataFormat object to adjust the way the field appears. Here is the code to do that:

HSSFWorkbook workbook;
private GetCellStyle(string cellStyle)
{
 CellStyle cs = workbook.CreateCellStyle();
 cs.DataFormat = workbook.CreateDataFormat().GetFormat("$#,##0.00_);($#,##0.00)");
}

And a cell style is set like so:

CellStyle currency = GetCellStyle("currency");
Row r7 = WS.GetRow(7);
r7.CreateCell(0).SetCellValue(dSomeCurrencyValue);
r7.GetCell(0).CellStyle = currency ;

So the current format surrounds negative numbers with parentheses. It was a small change to remove the parentheses and replace it with a minus sign:

cs.DataFormat = workbook.CreateDataFormat().GetFormat("$#,##0.00_);-$#,##0.00_)");