问题
What I'm trying to accomplish
I'm trying to create a function to use string interpolation within VBA. The issue I'm having is that I'm not sure how to replace "\n" with a vbNewLine
, as long as it does not have the escape character "\" before it?
What I have found and tried
VBScript does not have a negative look behind as far as I can research.
Below has two examples of Patterns that I have already tried:
Private Sub testingInjectFunction()
Dim dict As New Scripting.Dictionary
dict("test") = "Line"
Debug.Print Inject("${test}1\n${test}2 & link: C:\\notes.txt", dict)
End Sub
Public Function Inject(ByVal source As String, dict As Scripting.Dictionary) As String
Inject = source
Dim regEx As Object
Set regEx = CreateObject("VBScript.RegExp")
regEx.Global = True
' PATTERN # 1 REPLACES ALL '\n'
'regEx.Pattern = "\\n"
' PATTERN # 2 REPLACES EXTRA CHARACTER AS LONG AS IT IS NOT '\'
regEx.Pattern = "[^\\]\\n"
' REGEX REPLACE
Inject = regEx.Replace(Inject, vbNewLine)
' REPLACE ALL '${dICT.KEYS(index)}' WITH 'dICT.ITEMS(index)' VALUES
Dim index As Integer
For index = 0 To dict.Count - 1
Inject = Replace(Inject, "${" & dict.Keys(index) & "}", dict.Items(index))
Next index
End Function
Desired result
Line1
Line2 & link: C:\notes.txt
Result for Pattern # 1: (Replaces when not wanted)
Line1
Line2 & link: C:\
otes.txt
Result for Pattern # 2: (Replaces the 1 in 'Line1')
Line
Line2 & link: C:\\notes.txt
Summary question
I can easily write code that doesn't use Regular Expressions that can achieve my desired goal but want to see if there is a way with Regular Expressions in VBA.
How can I use Regular Expressions in VBA to Replace "\n" with a vbNewLine, as long as it does not have the escape character "\" before it?
回答1:
Yes, you may use a regex here. Since the backslash is not used to escape itself in these strings, you may modify your solution like this:
regEx.Pattern = "(^|[^\\])\\n"
S = regEx.Replace(S, "$1" & vbNewLine)
It will match and capture any char but \
before \n
and then will put it back with the $1
placeholder. As there is a chance that \n
appears at the start of the string, ^
- the start of string anchor - is added as an alternative into the capturing group.
Pattern details
(^|[^\\])
- Capturing group 1: start of string (^
) or (|
) any char but a backslash ([^\\]
)\\
- a backslashn
- an
char.
来源:https://stackoverflow.com/questions/49581881/how-to-mimic-regular-expression-negative-lookbehind