Visual Basic for Applications:
Deleting characters matching a pattern

How to:

In VBA, you can use the Replace function or regular expressions to delete characters matching a pattern. Here are examples of both methods:

Using the Replace Function

The Replace function is straightforward for removing specific characters or sequences.

Sub DeleteSpecificChars()
    Dim originalString As String
    originalString = "123-ABC-456-XYZ"
    
    ' Removing hyphens
    Dim resultString As String
    resultString = Replace(originalString, "-", "")
    
    Debug.Print originalString ' Before: 123-ABC-456-XYZ
    Debug.Print resultString ' After: 123ABC456XYZ
End Sub

Using Regular Expressions

For more complex patterns, regular expressions offer a powerful alternative.

First, enable the Microsoft VBScript Regular Expressions library via Tools > References in the Visual Basic Editor.

Sub DeletePatternChars()
    Dim regEx As Object
    Set regEx = CreateObject("VBScript.RegExp")
    
    Dim strPattern As String
    strPattern = "\d" ' Pattern to match all digits
    
    With regEx
        .Global = True
        .IgnoreCase = True
        .Pattern = strPattern
    End With
    
    Dim originalString As String
    originalString = "Remove 123 and 456"
    
    ' Using the Replace method to delete matches
    Dim resultString As String
    resultString = regEx.Replace(originalString, "")
    
    Debug.Print originalString ' Before: Remove 123 and 456
    Debug.Print resultString ' After: Remove  and 
End Sub

Deep Dive

Historically, pattern matching and string manipulation in VBA have been somewhat limited, particularly when compared to more modern programming languages which offer extensive standard libraries for these tasks. The Replace function is simple and efficient for direct substitutions but lacks the flexibility for more complex pattern matching. This is where regular expressions (RegEx) come in, providing a much richer syntax for pattern matching and string manipulation. However, working with RegEx in VBA requires additional setup, such as enabling the Microsoft VBScript Regular Expressions reference, which may be a barrier to newer users.

Despite these limitations, the introduction of RegEx support in VBA was a significant step forward, offering a more powerful tool for programmers working with text processing. In more complex scenarios where built-in string functions fall short, regular expressions provide a versatile and powerful option.

It’s worth noting that for those working in environments or projects where performance is critical, leveraging external libraries or integrating with other programming languages might provide better performance and more features. However, for many day-to-day tasks in VBA, these native methods remain a practical and accessible choice.