iot/projects/Infrastructure/Office/NPOIExtensions.cs

using NPOI.SS.UserModel;
using System.Collections.Generic;

namespace Infrastructure.Office
{
    public static class NPOIExtensions
    {
        public static IEnumerable<ISheet> GetSheets(this IWorkbook wookbook)
        {
            for (int i = 0; i < wookbook.NumberOfSheets; i++)
            {
                yield return wookbook.GetSheetAt(i);
            }
        }

        public static IEnumerable<IRow> GetRows(this ISheet sheet)
        {
            for (int i = 0; i < sheet.LastRowNum; i++)
            {
                yield return sheet.GetRow(i);
            }
        }

        public static IEnumerable<ICell> GetCells(this IRow row)
        {
            for (int i = 0; i < row.LastCellNum; i++)
            {
                yield return row.GetCell(i);
            }
        }

        public static object GetValue(this ICell cell)
        {
            object result = null;
            switch (cell.CellType)
            {
                case CellType.Unknown:
                    result = cell.ToString().Trim();
                    break;

                case CellType.Numeric:
                    result = cell.NumericCellValue;
                    break;

                case CellType.String:
                    result = cell.StringCellValue.Trim();
                    break;

                case CellType.Formula:
                    result = cell.CellFormula;
                    break;

                case CellType.Blank:
                    result = null;
                    break;

                case CellType.Boolean:
                    result = cell.BooleanCellValue;
                    break;

                case CellType.Error:
                    result = cell.ErrorCellValue;
                    break;

                default:
                    result = cell.ToString().Trim();
                    break;
            }
            return result;
        }
    }
}