Comments on: How to avoid VBScript regular expression gotchas

By: Samantha Small

Samantha Small — Mon, 12 May 2008 16:53:47 +0000

What Rubbish, they work perfectly for me….

By: David Gray

David Gray — Tue, 25 Mar 2008 01:39:24 +0000

First, regarding the debate about whether the way the VBScript Regular Expression engine handles the match expression “r\r\n\w” is a bug, that depends on your perspective. From the perspective of a person who learned them in the context of either Perl or a Unix gerp tool, this is incorrect. Even Win32 Perl behaves consistently, by treating the CR/LF pair as a single atom.

Second, this behavior appears to extend to the System.Text.Regex class of the Microsoft .NET Framework.

By: Alok Saldanha

Alok Saldanha — Fri, 02 Nov 2007 18:56:03 +0000

Any ideas why the following two patterns do not both match the embedded numbers in the string?

Sub foo()
processPattern “\d “
processPattern “\d*”
End Sub

Sub processPattern(pat As String)
Dim re As VBScript_RegExp_55.RegExp
Set re = New VBScript_RegExp_55.RegExp
Dim matches As VBScript_RegExp_55.MatchCollection
re.Pattern = pat
Set matches = re.Execute(”asdf234asdf”)
Debug.Print pat & ” returns ‘” & matches(0) & “‘”
End Sub

By: divVerent

divVerent — Sat, 08 Sep 2007 07:42:09 +0000

I tried to use that from VBA, and - of course - slammed into a bug.

Set reObj As New RegExp
With reObj
.Pattern = re
.MultiLine = True
End With
Set result = reObj.Execute(someString)
Set RE_Match_And_Capture = result(0).SubMatches

When my string is “hello” & vbCrLf & “world”, “^(.*)$” still just matches the “hello”. When I instead set MultiLine to False, the expression stops matching AT ALL! I then found that ^ and $ then correctly match just at beginning and end of the string, but that . still refuses to match newlines. I found that [^] is a working replacement for ., but still… this HAS to work. Or maybe I have just not seen some of the properties of the object? But the autocompletion SHOULD have showed me all…

In Perl, there is the multiline flag /…/m which seems to do exactly what MultiLine does (change the meaning of ^ and $ to be line-baseed), but what I really need is an equivalent of /…/s (changes the meaning of . to match everything, including newlines). Apparently, VBScript REs don’t support the “(?s)” way to set such flags either. So… how can I fix that problem?

By: Dave M

Dave M — Wed, 22 Aug 2007 03:11:54 +0000

Hmm I was just playing with vbscript regexps a few days ago and the expression “r\r\n\w” is not a bug at all.

windows files use 2 chars as line delimiter. 1. a ‘carriage return’ (Cr). 2. a ‘line feed’ (Lf). that’s why the end of line delimiter is ‘vbCrLf — and not ‘vbLf’. and that’s why \r\n is a match.

\r matches the carriage return char, and \n matches the line feed ( or newline) char. Thus “r\r\n\w” matches your example string perfectly.

Dave

By: deneshac

deneshac — Tue, 14 Aug 2007 20:33:53 +0000

Thank You for your reply, Potosino, it helped me look harder for a possible bug. I had the following experience:

Given the following two lines separated by a newline

test of r
what will come out?

I could not set the RegExp.Pattern to “r\nw”. It would match “r\r” (using just the CR) and it would match “\nw”. I finally tried them both together, and illogically it worked - “r\r\nw”.

I hate bugs! :)

chris

By: Potosino

Potosino — Wed, 16 Aug 2006 18:34:41 +0000

I had an experience with VBscript where I was trying to eliminate trailing blank spaces and tabs from lines of text. VBscript would not match the regular expression pattern [ \t]+$. Instead, I had to use something like ([ \t]+)[\n\r]{1,2} and replace it with vbCrLf.