Regular Expressions (Regex) in Excel VBA

Regular Expressions (Regex) in Excel VBA

Excel does not natively provide any Regex functions which often requires creating complex formulas for extracting pieces of strings otherwise easy to extract using Regular Expressions. Hence, to facilitate Regex in Excel you need to use User Defined Functions – functions defined in VBA but accessible as regular functions in Excel. Below find 2 basic UDF functions created just for this use:

Let us write the following function in Excel and save the file as macro enabled file:

You can copy from here as well or you can check the file attached at the end:

'Returns the number of matches found for a given regex 
'str - string to test the regex on
'reg - the regular expression 
Public Function RegexCountMatches(str As String, 
reg As String) As String 
   On Error GoTo ErrHandl 
   Set regex = CreateObject("VBScript.RegExp"): regex.Pattern 
= reg: regex.Global = True 
   If regex.test(str) Then 
      Set matches = regex.Execute(str) 
      RegexCountMatches = matches.Count 
      Exit Function 
   End If 
ErrHandl: 
   RegexCountMatches = CVErr(xlErrValue) 
End Function 

'Executes a Regular Expression on a provided string and 
returns a selected submatch 
'str - string to execute the regex on 
'reg - the regular expression with at least 1 capture '()' 
'matchIndex - the index of the match you want to return 
(default: 0) 
'subMatchIndex - the index of the submatch you want to 
return (default: 0) 
Public Function RegexExecute(str As String, reg As 
String, _ 
         Optional matchIndex As Long, _ 
         Optional subMatchIndex As Long) As String 
   On Error GoTo ErrHandl 
   Set regex = CreateObject("VBScript.RegExp"): 
   regex.Pattern = reg regex.Global = Not (matchIndex = 
0 And subMatchIndex = 0) 'For efficiency 
   If regex.test(str) Then 
      Set matches = regex.Execute(str) 
      RegexExecute = matches(matchIndex).SubMatches
(subMatchIndex) 
   Exit Function 
End If ErrHandl: 
   RegexExecute = CVErr(xlErrValue) 
End Function

Now you can check this in the Excel file like this:

Using formulas :

first match: =RegexExecute(B1,B2,0)

Second match: =RegexExecute(B1,B2,1)

No of matches: =RegexCountMatches(B1,B2) 

Template

Further reading: 
Basic concepts 
Getting started with Excel
Cell References