Pythonscript search different than N++ search when using \< and leading uppercase
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Well…what matters in regards to my script is that the regex search works correctly.
More philosophic, what means correct if we talk about regex.
As long as the same regex can be interpreted differently by different regex engines
how can we be sure what is right or wrong.I agree, I assumed too, that using the modifiers overrules the flags but with the regex
you used we see it isn’t. I don’t know if this is a bug in the implementation of the boost
regex engine or a bug of the boost regex engine. I don’t think that I will go in that detail.Concerning the correctness of the scripts - you found one misbehavior, I’m quite certain that others exist.
The bottom line is that the scripted search has a problem, and that problem is seemingly related to the use of < and > in the regex
Just to be clear, both, npp and pythonscript behave the same. It is not only python script which does this.
which I would like to be able to use. So, okay, we can “fix” that by working around it by playing with the flags stuff, and that is all fine, I guess.
From the test it looks like only the “start of word” and “end of word” word boundaries behave strange.
If you stop using this particular item you might have already solved it.
Until you discover the next issue.But should that become a general rule for using Pythonscript’s re.search() function, based upon someone finding one weird case?
Maybe there is no great answer to that at this point, but I’m attempting to create something general purpose,
where I can’t test all possible regexes for how they work at coding time, as they are input at run-time.
So I’m left wondering if the best thing to do when coding with editor.research() is to never embed (?i) or (?-i) in the regex,
and instead always use the flags parameter. Perhaps based upon the data we have at this moment, that is the best course of action.Personally, I’m avoiding now using the modifiers in scripts and using flags when needed.
Cheers
Claudia -
Wondering if it’s only an issue with
editor.research( ... ), as I have been using modifiers witheditor.rereplace( ... )successfully. -
Yep - same issue.
New doc with the word Print only
editor.rereplace('(?i)\<print\>', 'PRINT')fails where
editor.rereplace('\<print\>', 'PRINT', 2)works
UUhhh - I should avoid magic numbers - 2=re.I
Cheers
Claudia -
UUhhh - I should avoid magic numbers - 2=re.I
Damn right!!! LOL
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Hi, All,
I did some tests, using the classical Find dialog, with the original text, below :
xyz xYz xyZ xYZ Xyz XYz XyZ XYZ ----- 1xyz 1xYz 1xyZ 1xYZ 1Xyz 1XYz 1XyZ 1XYZ ----- xyz9 xYz9 xyZ9 xYZ9 Xyz9 XYz9 XyZ9 XYZ9 ----- 1xyz9 1xYz9 1xyZ9 1xYZ9 1Xyz9 1XYz9 1XyZ9 1XYZ9Then I tested the different regexes
-
xYZ -
xYZ\> -
xYZ\b -
\<xYZ -
\bxYZ -
\<xYZ\> -
\bxYZ\b -
(^|(?<=\W))xYZ((?=\W)|$) -
With the Match case option ON
-
With the Match case option OFF
-
Preceded by
(?i)and with the Match case option ON -
Preceded by
(?i)and with the Match case option OFF -
Preceded by
(?-i)and with the Match case option ON -
Preceded by
(?-i)and with the Match case option OFF
I obtained the six following tables, where :
-
A correct match is indicated by a
*character -
An incorrect match is indicated by the
Eletter ( Error )
+-------+------------------------------------------------------------------------------------+ | | Option "Match case" ON and Regex, below | | Text |-----+-------+-------+-------+-------+---------+---------+--------------------------| | | xYZ | xYZ\> | xYZ\b | \<xYZ | \bxYZ | \<xYZ\> | \bxYZ\b | (^|(?<=\W))xYZ((?=\W)|$) | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz | | | | | | | | | | xYz | | | | | | | | | | xyZ | | | | | | | | | | xYZ | * | * | * | * | * | * | * | * | | Xyz | | | | | | | | | | XYz | | | | | | | | | | XyZ | | | | | | | | | | XYZ | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz | | | | | | | | | | 1xYz | | | | | | | | | | 1xyZ | | | | | | | | | | 1xYZ | * | * | * | | | | | | | 1Xyz | | | | | | | | | | 1XYz | | | | | | | | | | 1XyZ | | | | | | | | | | 1XYZ | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz9 | | | | | | | | | | xYz9 | | | | | | | | | | xyZ9 | | | | | | | | | | xYZ9 | * | | | * | * | | | | | Xyz9 | | | | | | | | | | XYz9 | | | | | | | | | | XyZ9 | | | | | | | | | | XYZ9 | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz9 | | | | | | | | | | 1xYz9 | | | | | | | | | | 1xyZ9 | | | | | | | | | | 1xYZ9 | * | | | | | | | | | 1Xyz9 | | | | | | | | | | 1XYz9 | | | | | | | | | | 1XyZ9 | | | | | | | | | | 1XYZ9 | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ +-------+------------------------------------------------------------------------------------+ | | Option "Match case" OFF and Regex, below | | Text |-----+-------+-------+-------+-------+---------+---------+--------------------------| | | xYZ | xYZ\> | xYZ\b | \<xYZ | \bxYZ | \<xYZ\> | \bxYZ\b | (^|(?<=\W))xYZ((?=\W)|$) | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz | * | * | * | * | * | * | * | * | | xYz | * | * | * | * | * | * | * | * | | xyZ | * | * | * | * | * | * | * | * | | xYZ | * | * | * | * | * | * | * | * | | Xyz | * | * | * | * | * | * | * | * | | XYz | * | * | * | * | * | * | * | * | | XyZ | * | * | * | * | * | * | * | * | | XYZ | * | * | * | * | * | * | * | * | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz | * | * | * | | | | | | | 1xYz | * | * | * | | | | | | | 1xyZ | * | * | * | | | | | | | 1xYZ | * | * | * | | | | | | | 1Xyz | * | * | * | | | | | | | 1XYz | * | * | * | | | | | | | 1XyZ | * | * | * | | | | | | | 1XYZ | * | * | * | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz9 | * | | | * | * | | | | | xYz9 | * | | | * | * | | | | | xyZ9 | * | | | * | * | | | | | xYZ9 | * | | | * | * | | | | | Xyz9 | * | | | * | * | | | | | XYz9 | * | | | * | * | | | | | XyZ9 | * | | | * | * | | | | | XYZ9 | * | | | * | * | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz9 | * | | | | | | | | | 1xYz9 | * | | | | | | | | | 1xyZ9 | * | | | | | | | | | 1xYZ9 | * | | | | | | | | | 1Xyz9 | * | | | | | | | | | 1XYz9 | * | | | | | | | | | 1XyZ9 | * | | | | | | | | | 1XYZ9 | * | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ +-------+------------------------------------------------------------------------------------+ | | Option "Match case" ON and Regex, below, PRECEDED by (?i) | | Text |-----+-------+-------+-------+-------+---------+---------+--------------------------| | | xYZ | xYZ\> | xYZ\b | \<xYZ | \bxYZ | \<xYZ\> | \bxYZ\b | (^|(?<=\W))xYZ((?=\W)|$) | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz | * | * | * | * | * | * | * | * | | xYz | * | * | * | * | * | * | * | * | | xyZ | * | * | * | * | * | * | * | * | | xYZ | * | * | * | * | * | * | * | * | | Xyz | * | * | * | E | * | E | * | * | | XYz | * | * | * | E | * | E | * | * | | XyZ | * | * | * | E | * | E | * | * | | XYZ | * | * | * | E | * | E | * | * | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz | * | * | * | | | | | | | 1xYz | * | * | * | | | | | | | 1xyZ | * | * | * | | | | | | | 1xYZ | * | * | * | | | | | | | 1Xyz | * | * | * | | | | | | | 1XYz | * | * | * | | | | | | | 1XyZ | * | * | * | | | | | | | 1XYZ | * | * | * | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz9 | * | | | * | * | | | | | xYz9 | * | | | * | * | | | | | xyZ9 | * | | | * | * | | | | | xYZ9 | * | | | * | * | | | | | Xyz9 | * | | | E | * | | | | | XYz9 | * | | | E | * | | | | | XyZ9 | * | | | E | * | | | | | XYZ9 | * | | | E | * | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz9 | * | | | | | | | | | 1xYz9 | * | | | | | | | | | 1xyZ9 | * | | | | | | | | | 1xYZ9 | * | | | | | | | | | 1Xyz9 | * | | | | | | | | | 1XYz9 | * | | | | | | | | | 1XyZ9 | * | | | | | | | | | 1XYZ9 | * | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ -
-
I need to split this post in two parts because it exceeds 16384 characters !
+-------+------------------------------------------------------------------------------------+ | | Option "Match case" OFF and Regex, below, PRECEDED by (?i) | | Text |-----+-------+-------+-------+-------+---------+---------+--------------------------| | | xYZ | xYZ\> | xYZ\b | \<xYZ | \bxYZ | \<xYZ\> | \bxYZ\b | (^|(?<=\W))xYZ((?=\W)|$) | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz | * | * | * | * | * | * | * | * | | xYz | * | * | * | * | * | * | * | * | | xyZ | * | * | * | * | * | * | * | * | | xYZ | * | * | * | * | * | * | * | * | | Xyz | * | * | * | * | * | * | * | * | | XYz | * | * | * | * | * | * | * | * | | XyZ | * | * | * | * | * | * | * | * | | XYZ | * | * | * | * | * | * | * | * | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz | * | * | * | | | | | | | 1xYz | * | * | * | | | | | | | 1xyZ | * | * | * | | | | | | | 1xYZ | * | * | * | | | | | | | 1Xyz | * | * | * | | | | | | | 1XYz | * | * | * | | | | | | | 1XyZ | * | * | * | | | | | | | 1XYZ | * | * | * | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz9 | * | | | * | * | | | | | xYz9 | * | | | * | * | | | | | xyZ9 | * | | | * | * | | | | | xYZ9 | * | | | * | * | | | | | Xyz9 | * | | | * | * | | | | | XYz9 | * | | | * | * | | | | | XyZ9 | * | | | * | * | | | | | XYZ9 | * | | | * | * | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz9 | * | | | | | | | | | 1xYz9 | * | | | | | | | | | 1xyZ9 | * | | | | | | | | | 1xYZ9 | * | | | | | | | | | 1Xyz9 | * | | | | | | | | | 1XYz9 | * | | | | | | | | | 1XyZ9 | * | | | | | | | | | 1XYZ9 | * | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ +-------+------------------------------------------------------------------------------------+ | | Option "Match case" ON and Regex, below, PRECEDED by (?-i) | | Text |-----+-------+-------+-------+-------+---------+---------+--------------------------| | | xYZ | xYZ\> | xYZ\b | \<xYZ | \bxYZ | \<xYZ\> | \bxYZ\b | (^|(?<=\W))xYZ((?=\W)|$) | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz | | | | | | | | | | xYz | | | | | | | | | | xyZ | | | | | | | | | | xYZ | * | * | * | * | * | * | * | * | | Xyz | | | | | | | | | | XYz | | | | | | | | | | XyZ | | | | | | | | | | XYZ | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz | | | | | | | | | | 1xYz | | | | | | | | | | 1xyZ | | | | | | | | | | 1xYZ | * | * | * | | | | | | | 1Xyz | | | | | | | | | | 1XYz | | | | | | | | | | 1XyZ | | | | | | | | | | 1XYZ | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz9 | | | | | | | | | | xYz9 | | | | | | | | | | xyZ9 | | | | | | | | | | xYZ9 | * | | | * | * | | | | | Xyz9 | | | | | | | | | | XYz9 | | | | | | | | | | XyZ9 | | | | | | | | | | XYZ9 | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz9 | | | | | | | | | | 1xYz9 | | | | | | | | | | 1xyZ9 | | | | | | | | | | 1xYZ9 | * | | | | | | | | | 1Xyz9 | | | | | | | | | | 1XYz9 | | | | | | | | | | 1XyZ9 | | | | | | | | | | 1XYZ9 | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ +-------+------------------------------------------------------------------------------------+ | | Option "Match case" OFF and Regex, below, PRECEDED by (?-i) | | Text |-----+-------+-------+-------+-------+---------+---------+--------------------------| | | xYZ | xYZ\> | xYZ\b | \<xYZ | \bxYZ | \<xYZ\> | \bxYZ\b | (^|(?<=\W))xYZ((?=\W)|$) | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz | | | | | | | | | | xYz | | | | | | | | | | xyZ | | | | | | | | | | xYZ | * | * | * | * | | * | * | * | | Xyz | | | | | | | | | | XYz | | | | | | | | | | XyZ | | | | | | | | | | XYZ | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz | | | | | | | | | | 1xYz | | | | | | | | | | 1xyZ | | | | | | | | | | 1xYZ | * | * | * | | | | | | | 1Xyz | | | | | | | | | | 1XYz | | | | | | | | | | 1XyZ | | | | | | | | | | 1XYZ | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | xyz9 | | | | | | | | | | xYz9 | | | | | | | | | | xyZ9 | | | | | | | | | | xYZ9 | * | | | * | | | | | | Xyz9 | | | | | | | | | | XYz9 | | | | | | | | | | XyZ9 | | | | | | | | | | XYZ9 | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+ | 1xyz9 | | | | | | | | | | 1xYz9 | | | | | | | | | | 1xyZ9 | | | | | | | | | | 1xYZ9 | * | | | | | | | | | 1Xyz9 | | | | | | | | | | 1XYz9 | | | | | | | | | | 1XyZ9 | | | | | | | | | | 1XYZ9 | | | | | | | | | +-------+-----+-------+-------+-------+-------+---------+---------+--------------------------+
From these results, we can deduce than the N++ Boost regex engine lacks to match 4 ( or 8 ) cases, ONLY IF the four conditions, below, occur, simultaneously :
-
The Match case option, of the Find dialog, is ON
-
A
(?i)modifier starts the regex -
The regex begins with the
\<assertion -
The text, to match, begins with an UPPER letter
Luckily :
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The regex
\<xYZcan be changed by the regex\bxYZ -
The regex
\<xYZ\>can be changed by the regex\bxYZ\b
And note that :
-
The assertion
\<may be replaced by the assertion(^|(?<=\W)) -
The assertion
\>may be replaced by the assertion((?=\W)|$)
Cheers
guy038
BTW, Claudia, when you said :
I agree, I assumed too, that using the modifiers overrules the flags but with the regex
you used we see it isn’t.I disagree ! Indeed :
Considering the text below :
xyz xYz xyZ xYZ Xyz XYz XyZ XYZOf course, the two regexes
(?i)\<xYZand(?i)\<xYZ\>, with the Match case option ON, match the first four cases, onlyBut, the two regexes
(?i)\<XYZand(?i)\<XYZ\>, with the Match case option ON, ALSO match the first four cases, only !So, I do think that the in-line modifiers
(?i)and(?-i)have ALWAYS priority over the Match case optionAnd, like you, I rather think that it’s just a bug [ in the implementation ] of the Boost regex engine !
Besides, the two regexes
(?i)\bxYZand(?i)\bxYZ\b, with the Match case option ON, correctly match the eight cases, above, of the string “xyz” :-)) => The(?i)modifier forces the insensitive search ! -
-
Hi Guy,
thx for your effort on this but I have to disagree with your disagree ;-D
From regex execution point of view there are two ways to change
the case behavior. Either by providing a flag or using the in-line modifiers.
When providing the flag everything is ok (at least for the moment) - so
I have to assume that the regex engine works correctly in this case.
When providing the in-line modifier and the flags then it isn’t ok always.
This does mean there is a bug and it must be related to how in-line modifiers
are handled against flags. And that makes me think that the bug is when doing
this overwrite - which means we can’t rely on it. Maybe other in-line modifiers
together with some special regex constructs behave wrong as well.Cheers
Claudia -
Hello, Claudia and All,
Hum…,finally, Claudia, I think that you’re right :-) Indeed, if we built the general table, below, which recapitulates the main cases, it’s obvious that :
-
Results are OK, when the “Match case” flag, is ONLY used, WITHOUT any in-line modifier ( Lines 1 and 4 )
-
Results seem OK, ( UP TO NOW ), when the “Match case” flag is used, with a starting
(?-i)in-line modifier ( Lines 3 et 6 ) -
Results seem OK, ( UP TO NOW ), when the “Match case” flag is OFF, with a starting
(?i)in-line modifier ( Line 2 ) -
Results are
NOTOK, when the “Match case” flag is ON, with a starting(?i)in-line modifier and a regex which begins with the\<assertion ( Line 5 )
Luckily, this LAST case ( Line 5 ) is rather rare and does not occur if we use the
\bsyntax, instead of\<:-))+=======+=======================+====================+===========+==================+ | Row | "Match case" flag | In-line modifier | Results | Remarks | +=======+=======================+====================+===========+==================+ | 1 | OFF | NO | Correct | Implicit (?i) | +-------+-----------------------+--------------------+-----------+------------------+ | 2 | OFF | (?i) | Correct | | +-------+-----------------------+--------------------+-----------+------------------+ | 3 | OFF | (?-i) | Correct | | +=======+=======================+====================+===========+==================+ | 4 | ON | NO | Correct | Implicit (?-i) | +-------+-----------------------+--------------------+-----------+------------------+ | 5 | ON | (?i) | PROBLEM | IF use of \< | +-------+-----------------------+--------------------+-----------+------------------+ | 6 | ON | (?-i) | Correct | | +=======+=======================+====================+===========+==================+Cheers,
guy038
-
-
First of all, it is great to see such rousing discussion about the issue I discovered! :-) Thanks to all for that.
There are lots of things to think about coming out of this discussion, but the most obvious and immediate one is a question for Mr Guy: You keep suggesting to use \b instead of \< , but they are not always equivalent, correct? They may be equivalent for certain examples, but in the most general case I believe they are different. If they weren’t different, there would be no reason for both to exist in the N++/Boost engine…
I mean, even I discussed using \b instead in my very first posting in this thread, but that was just as a test, not necessarily a blanket substitution. I guess I don’t want others reading this thread to takeaway that \b and \< are the exact same thing.
Comments? Thoughts?
-
See reference on Word Boundaries for
- description on differences between
\b,\<and\>; - which “engine” supports what.
- description on differences between
-
Hi Alan and MapJe71,
Thanks, MapJe71, for the link about Word Boundaries, from the definitive site about regular expressions ! Of course, Alan, I know the differences between the three assertions :
\b,\<and\>. I just preferred not to speak about it, first, in order to keep concentrated on your problem !To be short, the
\bassertion acts, either, as a\<assertion OR as a\>assertion. This explains that the regex\<WORD\>can be simply replaced by the regex\bWORD\b.BTW, in the Words Boundaries table, I noticed the POSIX word boundaries (
[[:<:]]and[[:>:]]) which have, exactly, the same meaning as the GNU word boundaries\<and>\). These syntaxes are functional, with the N++ Boost regex engine ! Unfortunately, Alan, the problem that you noticed does occur with the POSIX word boundaries, too :-((.
On top of that, from the LAST row of the “Word Boundaries” table, named Word Boundaries behaviour, it is said that “word boundaries” are not correctly handled, in most regex engines :
Word boundaries always match at the start of the match attempt if that position is followed by a word character, regardless of the character that precedes the start of the match attempt. (Thus, word boundaries are not handled correctly for the second and following match attempts in the same string.)
And it shows an example :
\b. matches all of the letters but not the space when iterating over all matches, in the string “abc def”
So, I did some tests ( again !! )
- I copied this single sentence, below, part of the license.txt file, in a new tab
By contrast, the GNU General Public License is intended to guarantee your freedom...-
In the Find dialog, I left the Match case and the . matches newline options UNCHECKED
-
I selected, of course, the Regular expression search mode
-
I tested the different regexes, below, against the example text
REMARK : In the table, below, each dash character, under the sentence, indicates a match of the corresponding regex(es) !
======================================================================================================================== | REGEXES | EXAMPLE text - MATCHES noted by a DASH character | RESULTS | ======================================================================================================================== | | | | | | By contrast, the GNU General Public License is intended to guarantee your freedom... | INCORRECT ! | | (^|(?<!\w)). | ------------------------------------------------------------------------------------ | | | | | | +-----------------+--------------------------------------------------------------------------------------+-------------+ | | | | | \b. | | | | \<. | | | | [[:<:]]. | | | | | | | | | By contrast, the GNU General Public License is intended to guarantee your freedom... | INCORRECT ! | | \b\w | -- -------- --- --- ------- ------ ------- -- -------- -- --------- ---- ------- | | | \<\w | | | | [[:<:]]\w | | | | (^|(?<!\w))\w | | | | | | | +-----------------+--------------------------------------------------------------------------------------+-------------+ | | | | | | By contrast, the GNU General Public License is intended to guarantee your freedom... | INCORRECT | | (^|(?<=\W)). | - - - - - - - - - - - - - - | | | | | | +-----------------+--------------------------------------------------------------------------------------+-------------+ | | | (At last !) | | | By contrast, the GNU General Public License is intended to guarantee your freedom... | | | (^|(?<=\W))\w | - - - - - - - - - - - - - | CORRECT | | | | | ==================+======================================================================================+============== | | | | | | By contrast, the GNU General Public License is intended to guarantee your freedom... | INCORRECT ! | | .\b | -- - - -- -- -- -- -- -- -- -- -- -- - | | | | | | +-----------------+--------------------------------------------------------------------------------------+-------------+ | | | | | | | | | .((?=\W)|$) | By contrast, the GNU General Public License is intended to guarantee your freedom... | INCORRECT ! | | .((?!\w)|$) | - -- - - - - - - - - - - ---- | | | | | | | | | | +-----------------+--------------------------------------------------------------------------------------+-------------+ | | | | | .\> | | | | .[[:>:]] | | | | | | | | \w\b | By contrast, the GNU General Public License is intended to guarantee your freedom... | CORRECT | | \w\> | - - - - - - - - - - - - - | | | \w[[:>:]] | | | | \w((?=\W)|$) | | | | \w((?!\w)|$) | | | | | | | ========================================================================================================================
From that table, it obvious that the handle of the assertions, by the N++ Boost engine, seems quite weird !!!
To be coherent, only two regexes, with similar syntax, should be used :
-
The regex
(^|(?<=\W))\w, which matches the FIRST character of a word -
The regex
\w((?=\W)|$), which matches the LAST character of a word
=> The regex
(^|(?<=\W))\w|\w((?=\W)|$)matches the first AND the last characters of a wordBest Regards,
guy038
