筛选后如何获取正确的行范围导致excel互操作

Question

This is an extension of How do I access a cell in Excel Interop when using filtered ranges?

Why does the first segment of code iterate through the correct number of rows, but the second segment continue beyond the range of rows? To recap:

   range = ws.UsedRange;
   for (int row = 3; row <= range.Rows.Count; row++)
    {
        Object nObj = ((Excel.Range)ws.Cells[row, "N"]).Text;
    }

Iterates through the correct number of rows but does not take into account filtered rows.

   range = ws.UsedRange.SpecialCells(Excel.XlCellType.xlCellTypeVisible, Type.Missing);
    foreach (Excel.Range area in range.Areas)
    {
        foreach (Excel.Range row in area.Rows)
            //for (int row = 3; row <= range.Rows.Count; row++)
            {
                Object nObj = ((Excel.Range)row.Cells[1, 14]).Text;
            }
    }

Takes into account filtered rows but the inner loop continues beyond the rage of rows per area.

Answer 1

The outer loop across areas seems redundant. You could try removing it and changing the inner loop to

foreach (Excel.Range row in range.Rows)

Furthermore, Range.UsedRange is known to sometimes return unexpected results. See http://www.vbaexpress.com/kb/getarticle.php?kb_id=82

There are several alternatives:-

1. range = ((Excel.Range)ws.Cells[1, 1]).CurrentRegion - if your range has at least one column which has continuous values (no gaps) then this should work well.

2. Name the range explicitly, so that you can just do range = ws.Range("MyRange")

3. Find the last row of your range and construct the target range using the first row and last row, eg range = ws.Range(ws.Cells[1, 1], ((Excel.Range)ws.Cells[1048576,1]).End(xlUp)).EntireRow (note that 1048576 is the highest row index in Excel 2007 and Excel 2010 and 65536 is the highest row index in earlier versions). Here I am using the first column of the range to determine the last row of the range by calling End(xlUp) on the cell at the bottom of the worksheet in that first column. This requires that the column does not contain any empty values within the data. If the first column can contain empty values, then you should use another column, which is guaranteed to have a value in your data.

Also, to preserve your skipping of the first two rows, you could try:-

using System.Linq;

foreach (Excel.Range row in range.Rows.Skip(2))

(Obviously if you used alternative method 3 to determine your target range then you could set the first row to be row 3 instead of row 1 by using ws.Cells[3, 1] as the top bound of the range, so you would not have to call Skip() in this manner).