Microsoft Office

VBA Examples 44
The following example demonstrates how to loop through all the cells in a range. In this case, the range is
the current selection. In this example, Cell is a variable name that refers to the cell being processed.
(Notice that this variable is declared as a Range object.) Within the For-Next loop, the single statement
evaluates the cell. If the cell is negative, it’s converted to a positive value.
Sub ProcessCells()
Dim Cell As Range
For Each Cell In Selection
If Cell.Value < 0 Then Cell.Value = Cell.Value * -1
Next Cell
End Sub
The preceding example works, but what if the selection consists of an entire column or an entire range?
This is not uncommon because Excel lets you perform operations on entire columns or rows. But in this
case, the macro seems to take forever because it loops through each cell — even those that are blank. What’s
needed is a way to process only the nonblank cells.
You can accomplish this task by using the SelectSpecial method. In the following example, the
SelectSpecial method is used to create a new object: the subset of the selection that consists of cells
with constants (as opposed to formulas). This subset is processed, with the net effect of skipping all blank
cells and all formula cells.
Sub ProcessCells2()
Dim ConstantCells As Range
Dim Cell As Range
‘ Ignore errors
On Error Resume Next
‘ Process the constants
Set ConstantCells = Selection.SpecialCells(xlConstants, xlNumbers)
For Each Cell In ConstantCells
If Cell.Value < 0 Then Cell.Value = Cell.Value * -1
Next Cell
End Sub
The ProcessCells2 procedure works fast, regardless of what is selected. For example, you can select the
range, select all columns in the range, select all rows in the range, or even select the entire worksheet. In all
these cases, only the cells that contain constants are processed inside of the loop. This procedure is a vast
improvement over the ProcessCells procedure presented earlier in this section.
Notice that the following statement is used in the procedure:
On Error Resume Next
This statement causes Excel to ignore any errors that occur and simply to process the next statement. This
statement is necessary because the SpecialCells method produces an error if no cells qualify and
because the numerical comparison will fail if a cell contains an error value. Normal error checking is
resumed when the procedure ends. To tell Excel explicitly to return to normal error-checking mode, use the
following statement:
On Error GoTo 0
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