//获取单元格的公式值
String temp;
if (row.GetCell(0).CellType == CellType.Formula)
temp = row.GetCell(0).NumericCellValue.ToString();
else
temp = row.GetCell(0).ToString();
//设置单元格格式为0.00,
IDataFormat dataformat = workbook.CreateDataFormat();
ICellStyle style0 = workbook.CreateCellStyle();
style0.DataFormat = dataformat.GetFormat("0.00");
IRow row = sheet.CreateRow(0);
row.CreateCell(0).CellStyle = style0;
row.GetCell(0).SetCellValue(1);