Most efficient technique to check lots of cells contain an error? - vba

Question

I have a spreadsheet which contains lots of function calls to request data. I am writing a function (in VBA) to check whether any of the cells contains an error value "#VALUE" etc.
At the moment I am iterating row by row, column by column and first checking if the cell contains a formula, then if it does, checking instr for "#VALUE", "#N/A" etc.
However, I was wondering whether it would be quicker simulating clicking a whole column in excel and then "ctrl + f" for a value... in VBA.
What would be the most efficient way? I am checking a sheet 27 columns x 1200 rows large.
EDIT Ive just realised there are some cells which have "#N/A" and this is because they do not contain a particular formula. I need to only search in cells which contain a particular formula.... is this possible?
EDIT2 I effectively need to record a macro which returns the resutls, exactly like "find all". I have used "find" and i can get a boolean, but "find all" doesnt record any VBA code....

Answer 1

You can use SpecialCells to return only cells containing errors.
Sub Demo()
Dim sh As Worksheet
Dim rng As Range, cl As Range
For Each sh In ActiveWorkbook.Worksheets
Set rng = Nothing
On Error Resume Next
Set rng = sh.UsedRange.SpecialCells(xlCellTypeFormulas, xlErrors)
On Error GoTo 0
If rng Is Nothing Then
Debug.Print "No Errors"
Else
For Each cl In rng
If cl.Formula Like "*" Then ' <-- replace * with your criteria
Debug.Print cl.Address
End If
Next
End If
Next
End Sub

Answer 2

Given you wanted the most efficient method you could try this approach which avoids a slow range loop
Loops through SpecialCells formulae chichi contain errors (as per the other solution)
Uses Find to detect specific formulae rather than a simple loop through every cell in (1)
This code uses the R1C1 method to feed into the Find so the code changes this Application setting if necessary (and then back at the end)
I suggest you record the formula you wish to find to then enter this in. The big advantage of R1C1 notation is that it is agnostic of actual row and column location.
For example in A1 notation a formula of
=SUM(A1:A4) in A5 would require a different search for SUM(B1:B4) inB5`
in R1C1 this is =SUM(R[-4]C:R[-1]C) in both cases
code
Sub Demo()
Dim ws As Worksheet
Dim rng1 As Range
Dim rng2 As Range
Dim rng3 As Range
Dim strAddress As String
Dim bRefSTyle
If Application.ReferenceStyle = xlA1 Then
Application.ReferenceStyle = xlR1C1
bRefSTyle = True
End If
For Each ws In ActiveWorkbook.Worksheets
Set rng1 = Nothing
On Error Resume Next
Set rng1 = ws.UsedRange.SpecialCells(xlCellTypeFormulas, xlErrors)
On Error GoTo 0
If rng1 Is Nothing Then
Debug.Print ws.Name & ": No Formulae errors"
Else
'search errors for particular formula
'this sample looks for a formula which SUMS the four cells directly above it
Set rng2 = rng1.Find("=SUM(R[-4]C:R[-1]C)", , xlFormulas, xlWhole)
If Not rng2 Is Nothing Then
strAddress = rng2.Address
Set rng3 = rng2
Do
Set rng2 = rng1.Find("=SUM(R[-4]C:R[-1]C)", rng2, xlFormulas, xlWhole)
Set rng3 = Union(rng2, rng3)
Loop While strAddress <> rng2.Address
Debug.Print ws.Name & ": " & rng3.Address
Else
Debug.Print ws.Name & ": error cells, but no formulae match"
End If
End If
Next
'restore styles if necessary
If bRefSTyle Then Application.ReferenceStyle = xlA1
End Sub