Find all used references in Excel formula - vba

Question

Below is the example set in Excel,
[column1] [column2]
A1 =C3-C5
A2 =((C4-C6)/C6)
A3 =C4*C3
A4 =C6/C7
A5 =C6*C4*C3
I need to extract the used references in formulas
For example,
for "A1", I simply need to get the C3 and C5.
for A2, I need to get the C4 and C6.

Answer 1

This is an update to:
Will work for local sheet references, but not for references off-sheet. – brettdj May 14 '14 at 11:55
By Using Larrys method, just change the objRegEx.Pattern to:
(['].*?['!])?([[A-Z0-9_]+[!])?(\$?[A-Z]+\$?(\d)+(:\$?[A-Z]+\$?(\d)+)?|\$?[A-Z]+:\$?[A-Z]+|(\$?[A-Z]+\$?(\d)+))
This will:
Search for optional External links: (['].*?['!])?
Search for optional Sheet-reference: ([[A-Z0-9_]+[!])?
Do the following steps in prioritized order:
Search for ranges with row numbers (And optional $): \$?[A-Z]+\$?(\d)+(:\$?[A-Z]+\$?(\d)+)?
Search for ranges without row numbers (And optional $): \$?[A-Z]+:\$?[A-Z]+
Search for 1-cell references (And optional $): (\$?[A-Z]+\$?(\d)+)
Resulting in this:
Sub testing()
Dim result As Object
Dim r As Range
Dim testExpression As String
Dim objRegEx As Object
Set r = Cells(1, 2) ' INPUT THE CELL HERE , e.g. RANGE("A1")
Set objRegEx = CreateObject("VBScript.RegExp")
objRegEx.IgnoreCase = True
objRegEx.Global = True
objRegEx.Pattern = """.*?""" ' remove expressions
testExpression = CStr(r.Formula)
testExpression = objRegEx.Replace(testExpression, "")
objRegEx.Pattern = "(([A-Z])+(\d)+)" 'grab the address
objRegEx.Pattern = "(['].*?['!])?([[A-Z0-9_]+[!])?(\$?[A-Z]+\$?(\d)+(:\$?[A-Z]+\$?(\d)+)?|\$?[A-Z]+:\$?[A-Z]+|(\$?[A-Z]+\$?(\d)+))"
If objRegEx.test(testExpression) Then
Set result = objRegEx.Execute(testExpression)
If result.Count > 0 Then
For Each Match In result
Debug.Print Match.Value
Next Match
End If
End If
End Sub
Doing this, will give you the values of all possible references, I could think of. (Updated this post, because I needed the problem solved).

Answer 2

This function returns you a comma separated list of source cells (precedents):
Function References(rngSource As Range) As Variant
Dim rngRef As Range
Dim strTemp As String
On Error Resume Next
For Each rngRef In rngSource.Precedents.Cells
strTemp = strTemp & ", " & rngRef.Address(False, False)
Next
If Len(strTemp) 0 Then strTemp = Mid(strTemp, 3)
References = strTemp
End Function
However, please note that you cannot use this as a UDF in the worksheet, as rngRef.Address unfortunately causes a circular reference. However, you can use it in a small procedure to populate another column, e.g.
Sub ShowPrecedents()
Dim rng As Range
'Will paste precedents of A1:A6 into D1:D6
For Each rng In Range("D1:D6")
rng.Value = References(rng.Offset(, -3))
Next
End Sub

Answer 3

Just to provide you an alternative... NOTE THAT THIS will return duplicate result if the cells are called more than once
Sub testing()
Dim result As Object
Dim r As Range
Dim testExpression As String
Dim objRegEx As Object
Set r = Cells(1, 2) ' INPUT THE CELL HERE , e.g. cells("A1")
Set objRegEx = CreateObject("VBScript.RegExp")
objRegEx.IgnoreCase = True
objRegEx.Global = True
objRegEx.Pattern = """.*""" ' remove expressions
testExpression = CStr(r.Formula)
testExpression = objRegEx.Replace(testExpression, "")
objRegEx.Pattern = "(([A-Z])+(\d)+)" 'grab the address
If objRegEx.test(testExpression) Then
Set result = objRegEx.Execute(testExpression)
If result.Count > 0 Then
For Each Match In result
Debug.Print Match.Value
Next Match
End If
End If
End Sub
Results are stored in "Match.Value"