# \[X\] regular expressions not working correctly

**URL:** https://community.mp3tag.de/t/x-regular-expressions-not-working-correctly/12298
**Category:** No Bugs
**Created:** [July 20, 2011, 1:33am UTC](https://community.mp3tag.de/t/x-regular-expressions-not-working-correctly/12298 "2011-07-20T01:33:40Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![chrizoo](https://community.mp3tag.de/user_avatar/community.mp3tag.de/chrizoo/32/233_2.png) [@chrizoo](https://community.mp3tag.de/u/chrizoo)
#### Post date: [July 20, 2011, 1:33am UTC](https://community.mp3tag.de/t/x-regular-expressions-not-working-correctly/12298/1 "2011-07-20T01:33:40Z")

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It seems character classes [...] are not working in MP3Tag's implementation of regular expressions, as

**$regexp(%\_tag%,(ID3\w\*)._,$1)_** matches **ID3v1**  
but  
**$regexp(%\_tag%,(ID3[\w])._,$1)_** only matches **ID3** _(should match ID3v1)_  
**$regexp(%\_tag%,(ID3[^]).\*,$1)** only matches **ID3** _(should match ID3v1)_  
   
(%\_tag% = "ID3v1 Lyrics3v2 ID3v2.4 APEv2")

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### Author: ![DetlevD](https://community.mp3tag.de/user_avatar/community.mp3tag.de/detlevd/32/123_2.png) [@DetlevD](https://community.mp3tag.de/u/DetlevD)
#### Post date: [July 20, 2011, 3:01am UTC](https://community.mp3tag.de/t/x-regular-expressions-not-working-correctly/12298/2 "2011-07-20T03:01:33Z")

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> [@chrizoo](#):
>
> It seems character classes [...] are not working in MP3Tag's implementation of regular expressions ...

Try this ...

**$regexp(%\_tag%,'(ID3\w\*).\*','$1')****$regexp(%\_tag%,'(ID3[\w]\*).\*','$1')****$regexp(%\_tag%,'(ID3[^]\*).\*','$1')**

DD.20110720.0704.CEST

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### Author: ![chrizoo](https://community.mp3tag.de/user_avatar/community.mp3tag.de/chrizoo/32/233_2.png) [@chrizoo](https://community.mp3tag.de/u/chrizoo)
#### Post date: [July 20, 2011, 11:16am UTC](https://community.mp3tag.de/t/x-regular-expressions-not-working-correctly/12298/3 "2011-07-20T11:16:35Z")

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your version (with **'...'** wrapped around) works. what is the reason for this? Why are quotes ( **'** ) needed at all?

I finally settled for $regexp(%\_tag%,(ID3\S\*).\*,$1) which also works.

however **\S** and **[^]** is strictly the same thing, so both variants should work.

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### Author: ![DetlevD](https://community.mp3tag.de/user_avatar/community.mp3tag.de/detlevd/32/123_2.png) [@DetlevD](https://community.mp3tag.de/u/DetlevD)
#### Post date: [January 18, 2012, 9:24am UTC](https://community.mp3tag.de/t/x-regular-expressions-not-working-correctly/12298/4 "2012-01-18T09:24:18Z")

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> [@chrizoo](#):
>
> ... however **\S** and **[^]** is strictly the same thing ...

It is strictly not the same thing.  
Character class \s contains spaces, tabs, and line breaks.  
Character class \S is the negated version of class \s.

DD.20120118.1124.CET

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### Author: ![Florian](https://community.mp3tag.de/user_avatar/community.mp3tag.de/florian/32/5759_2.png) [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [December 28, 2018, 2:30pm UTC](https://community.mp3tag.de/t/x-regular-expressions-not-working-correctly/12298/5 "2018-12-28T14:30:32Z")

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