How to Implement Regular Expressions in Microsoft Excel Using VBA

To implement regular expressions in Excel, a custom Visual Basic for Applications (VBA) function must be created and configured. This function can then be called directly within Excel worksheets.Follow these steps to set up and use regular expressions:

1. Access the Visual Basic Editor:

   While in an Excel sheet, press Alt-F11 to open the Visual Basic Editor.

2. Insert a New Module:

   In the VBA Project Explorer, right-click and select 'Insert' > 'Module'.

3. Import RegEx Modules:

   Go to 'Tools' > 'References' and select the checkbox for 'Microsoft VBScript Regular Expressions 5.5'. Click OK.

4. Enable Macros:

   • Navigate to the 'Developer' tab in Excel. If the 'Developer' tab is not visible, go to 'File' > 'Options' > 'Customize Ribbon' and select the Developer sub-tab in the main tab menu on the right.
   • Click 'Macro Security' within the Developer tab to adjust settings as needed.

5. Implement the Custom Function:

   Insert the following Visual Basic Script into the newly created module. This function, TestRegExp, finds all matches for a given regular expression pattern within a string. Note that double quotes are required for the regex pattern when calling the function in Excel.

vbaFunction TestRegExp(myPattern As String, myString As String)'Create objects.Dim objRegExp As RegExpDim objMatch As MatchDim colMatches As MatchCollectionDim RetStr As String' Create a regular expression object.Set objRegExp New RegExpobjRegExp.Pattern myPatternobjRegExp.IgnoreCase TrueobjRegExp.Global TrueIf (objRegExp.Test(myString) True) ThenSet colMatches  objRegExp.Execute(myString)   ' Execute search.For Each objMatch In colMatches   ' Iterate Matches collection.  RetStr  RetStr & objMatch.ValueNextElseRetStr  "String Matching Failed"End IfTestRegExp RetStrEnd Function

This function returns all matches concatenated. To retrieve only the first match, modify the RetStr assignment within the For Each loop to:RetStr colMatches(0).ValueAn example file containing this function can be downloaded from:https://dl.dropboxusercontent.com/u/18899591/RegExFunctionForExcel.bas