What to do with error 1004 in loop through column? - excel

Question

I'm trying to use this code for showing the overflow to another value in the column I in sheet 20170224-SUAGDB. But I'm getting an Error 1004 about the line If Works....Value Then. Can somebody help me with the error?
Dim i As Long
For i = 2 To Rows.Count
If Worksheets("20170224-SUAGDB").Cells(i, 9).Value <> Worksheets("20170224-SUAGDB").Cells((i + 1), 9).Value Then
Cells(i, 9).Font.Color = vbRed
End If
Next i

Answer 1

Since you haven't .select'ed any specific Range() in your Worksheet, your Rows.Count value is equal to 1048576.
You can check it's value using MsgBox Rows.Count.
So, when your loop goes from 1 to 1048576, in the last iteration when you try to compare .Cells(i, 9).Value with .Cells((i + 1), 9).Value, the second term "explodes" your total number of rows!
Your code looks for the row number 1048577 - which don't exists - so it throws a 1004 error.
One possible solutions is changing :
This: For i = 2 To Rows.Count
To this: For i = 2 To Rows.Count - 1
This solution will loop through all - 1 rows even if they don't contain any data.
Or maybe even:
This: For i = 2 To Rows.Count
To this: For i = 2 To Range("I:I").End(xlDown).Row - 1
This solution get the last non-blank row value of the selected column.
ps. If you don't add - 1 in For i = 2 To Range("I:I").End(xlDown).Row - 1, and your worksheet contains some data at the row number 1048576, your code will throw the same error 1004.

Answer 2

Some of your objects are not fully qualified. For instance, get the last row number in column "I" (9) in `Worksheets("20170224-SUAGDB").
Try the code below:
Dim i As Long
With Worksheets("20170224-SUAGDB")
For i = 2 To .Cells(.Rows.Count, 9).End(xlUp).Row '<-- get last row in column "I" (column 9)
If .Cells(i, 9).Value <> .Cells((i + 1), 9).Value Then
.Cells(i, 9).Font.Color = vbRed
End If
Next i
End With