Wildcards in 'Replace With' Text

Anne-Mie realizes that she can use wildcards (*?) to search in Excel, but she wonders if she can use wildcards in the replace string. For instance, she would like to search for "ab*de" and replace it with "aa*de", where the asterisk represents any number of characters, or none at all.

The short answer is that there is no way to do this in Excel, as described. If you only wanted to convert the second character of a text value from "b" to "a", then that can be done rather easily:

=REPLACE(A1,2,1,"a")

This, however, is probably not what you want to do; you want a way to use wildcards in the "replace with" text. The technical term for doing such string replacements is called REGEX, which is short for Regular Expressions. REGEX started with languages like Perl but was so powerful that many other programming languages added it on.

The VBA used in Excel is no exception. REGEX was added to Visual Basic 6.0, which means that it made its way to Excel's VBA in Excel 2003. The first step in using REGEX is to turn it on. You do this in the VBA Editor by choosing Tools | References and then making sure there is a check mark next to the Microsoft VBScript Regular Expressions 5.5 option.

Enabling this reference allows you to create REGEX objects. These objects possess a Test method and a Pattern property. This means that you set the Pattern property, and then the Test method checks to see if the pattern exists. A REGEX object also has a Replace method, which is used to do replacements.

Before proceeding, it is important to understand that regular expressions can get very complex and, well, "geeky." There is no way around it; how to work with regular expressions has been the subject of entire books. Fortunately, for the purposes of this tip, the expressions are rather simple in nature. In this case we'll use the pattern "^ab.*de$". This pattern refers to a word that starts (indicated by the ^) with "ab" followed by an arbitrary expression (indicated by *) consisting of at least one character (indicated by the period) and ending (indicated by the $) with "de".

Here is the code that implements the use of the REGEX object to do the actual replacements.

Public Function SearchNReplace1(Pattern1 As String, _
  Pattern2 As String, Replacestring As String, _
  TestString As String)
    Dim reg As New RegExp

    reg.IgnoreCase = True
    reg.MultiLine = False
    reg.Pattern = Pattern1
    If reg.Test(TestString) Then
        reg.Pattern = Pattern2
        SearchNReplace = reg.Replace(TestString, ReplaceString)
    Else
        SearchNReplace = TestString
    End If
End Function

To use this macro, start with the strings you want to change in column A. Assuming that the first string is in cell A1, you could place the following into another cell in order to get the changed text:

=SearchNReplace1("^ab.*de$","^ab","aa",A1)

This tells the macro that the pattern you want to look for is "^ab.*de$" (the first parameter), and that you want to replace "^ab" with "aa". This formula can be pasted down the column, and you end up with a conversion of column A where the string "ab*de" is replaced by "aa*de".

If you are using an older version of Excel that does not allow you to create REGEX objects, or if you would prefer not to do so, then you can create a macro that will simply step through a group of selected cells and look for any cell that begins with "ab" and ends with "de", and then replaces the beginning part with "aa".

Sub SearchNReplace2()
    Dim sFindInitial As String
    Dim sReplaceInitial As String
    Dim iLenInitial As Integer
    Dim sFindFinal As String
    Dim sReplaceFinal As String
    Dim iLenFinal As Integer
    Dim sTemp As String
    Dim rCell As Range

    sFindInitial = "ab"
    sReplaceInitial = "aa"
    sFindFinal = "de"
    sReplaceFinal = "de"

    For Each rCell In Selection
        sTemp = rCell.Value
        iLenInitial = Len(sFindInitial)
        iLenFinal = Len(sFindFinal)
        If Left(sTemp, iLenInitial) = sFindInitial And _
            Right(sTemp, iLenFinal) = sFindFinal Then
            sTemp = Mid(sTemp, iLenInitial + 1)
            sTemp = Left(sTemp, Len(sTemp) - iLenFinal)
            sTemp = sReplaceInitial & sTemp & sReplaceFinal
            rCell.Value = sTemp
        End If
    Next
    Set rCell = Nothing
End Sub

To use this routine, simply select the cells you want to change, and then execute the macro. You should also make changes to the sFindInitial, sReplaceInitial, sFindFinal, and sReplaceFinal variables, as needed.