Question

I have a large Excel sheet auto generated from C#, which outputs all columns as text (this cannot be changed for technical reasons). I am having trouble writing a macro which will convert the numeric columns to numbers, and do it fast (the sheet contains 80 columns and 20,000 rows).

I have tried iterating over all cells and calling

If IsNumeric(cell.Value) Then cell.Value = CDec(cell.Value)

This is very slow AND has the additional problem that I have a special case where strings starting with things such as “0xxx” need to be kept as a string. If I used IsNumeric and then convert to CDec, I LOSE the leading 0!

Is there some simple trick to say detect if one value in a column is a string, then do NOT process the column, else convert them to numeric EXCEPT for the case where we have a leading 0?

Answer 1

Does storing the value in memory and doing your checking work? Something similar to the below code, but you would have to refine it and replace condition_is_true for something meaningful. I would use a function to return back a boolean.

Dim input_var As String

For r = 1 To 20000
    For c = 1 To 80
        input_var = Sheet1.Cells(r, c).value
        'do some stuff to the string

        If condition_is_true Then
            Sheet1.Cells(r, c).value = CDec(input_var)
        Else
            Sheet1.Cells(r, c).value = input_var
        End If
    Next c
Next r