C# NPOI: Get Cell String Value with Case Handling

The method 'NPOIUtil.GetCellStringValueAllCase' is not a built-in method in C# or the NPOI library. It seems to be a custom method specific to your codebase or project.

To understand how this method works, you would need to look at its implementation in your codebase. It is likely a utility method that retrieves the string value of a cell in an Excel file using the NPOI library, while handling different possible cases (such as upper case, lower case, etc.).

Here's an example of how such a method could be implemented:

public static string GetCellStringValueAllCase(ICell cell)
{
    if (cell == null)
    {
        return null;
    }

    CellType cellType = cell.CellType;
    string cellValue = "";

    switch (cellType)
    {
        case CellType.String:
            cellValue = cell.StringCellValue;
            break;
        case CellType.Numeric:
            cellValue = cell.NumericCellValue.ToString();
            break;
        case CellType.Boolean:
            cellValue = cell.BooleanCellValue.ToString();
            break;
        // Handle other cell types as needed

        default:
            cellValue = "";
            break;
    }

    // Convert the cell value to the desired case (e.g., lower case, upper case, etc.)
    cellValue = cellValue.ToLower(); // Example: converting to lower case

    return cellValue;
}

Note that this is just a sample implementation, and the actual implementation in your codebase may differ.