NPOI does not evaluate 3d formula - npoi

Question

I'm using NPOI to read data from Excel 2003 files. These files contains formulas like this SUM('1:2'!$C$17). NPOI recognized such formulas like SUM('1'!$C$17) (w/o sheet 2) and evaluate invalid result.
I'm using a regular code from NPOI examples, like
foreach (var row in docRows)
{
sb.AppendFormat("{0}\t", SomeCode);
rowCounter += 1;
sb.AppendFormat("{0}\t", rowCounter);
foreach (var col in docColumns)
{
ICell cell = sheet.GetRow(row).GetCell(col);
sb.AppendFormat("{0}\t", GetExcelCellValue(cell));
}
sb.AppendLine();
}
private string GetExcelCellValue(ICell cell)
{
string cellValue = string.Empty;
IFormulaEvaluator evaluator = _hssfworkbook.GetCreationHelper().CreateFormulaEvaluator();
evaluator.Evaluate(cell);
switch (evaluator.EvaluateInCell(cell).CellType)
{
case CellType.BLANK:
cellValue = string.Empty;
break;
case CellType.BOOLEAN:
cellValue = string.Empty;
break;
case CellType.NUMERIC:
cellValue = Convert.ToString(cell.NumericCellValue); //This is a trick to get the correct value of the cell. NumericCellValue will return a numeric value no matter the cell value is a date or a number.
break;
case CellType.STRING:
throw new ArgumentNullException();
cellValue = cell.StringCellValue;
break;
case CellType.ERROR:
cellValue = string.Empty;
break;
case CellType.FORMULA:
break;
}
return cellValue;
}

Answer 1

I have just encountered this problem and I solved it by
switch (cell.CellType)
{
case CellType.Blank:
cellValue = "";
break;
case CellType.Boolean:
cellValue = cell.BooleanCellValue.ToString();
break;
case CellType.Formula:
cellValue = cell.NumericCellValue.ToString();
break;
case CellType.Numeric:
cellValue = cell.NumericCellValue.ToString();
break;
case CellType.String:
cellValue = cell.StringCellValue;
break;
}