Lookbehind on regex for VBA?

问题

Is there a way to do negative and positive lookbehind in VBA regex?

I want to not match if the string starts with \"A\", so I am currently doing ^A at the start of the pattern, then removing the first character of match(0). Obviously not the best method!

I am using the regExp object.

回答1:

VBA offers positive and negative lookaheads but rather inconsistently not lookbehind.

The best example of using Regex with VBA that I have seen is this article by Patrick Matthews

[Updated example using Execute rather than Replace]

While I am not completely clear on your usage you could use a function like this with

skips any words starting with A

for all words not starting with a it returns everything from the second character on (using a submatch - the pattern inside ( and ) is submatch 1 -

Sub TestString()
MsgBox ReducedText("cfat dcat")
MsgBox ReducedText("Sat all over the hat again")
End Sub


Function ReducedText(strIn As String) As String
Dim objRegex As Object
Dim objRegMC As Object
Dim objRegM As Object
Dim strOut As String
Set objRegex = CreateObject("vbscript.regexp")
With objRegex
  .IgnoreCase = True
  'not needed if matching the whole string
  .Global = True
  .Pattern = "\b[^a\s]([a-z]+)"
  If .test(strIn) Then
      Set objRegMC = .Execute(strIn)
      For Each objRegM In objRegMC
        strOut = strOut & objRegM.submatches(0) & vbNewLine
      Next
      ReducedText = strOut
  Else
    ReducedText = "Starts with A"
  End If
End With
End Function

回答2:

How about putting the ^A in a non-captured group and using the SubMatches property of the Match object to get your matched value?

来源：https://stackoverflow.com/questions/9150552/lookbehind-on-regex-for-vba

标签

regex

vba

lookbehind

negative-lookbehind