# I need help understanding $regex in mp3tag **URL:** \ **Category:** Support\ **Created:** [December 8, 2020, 9:38pm UTC](https://community.mp3tag.de/t/i-need-help-understanding-regex-in-mp3tag/51085 "2020-12-08T21:38:56Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Moibilak7](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/m/3e96dc/32.png) [@Moibilak7](https://community.mp3tag.de/u/Moibilak7)\ **Post date:** [December 8, 2020, 9:38pm UTC](https://community.mp3tag.de/t/i-need-help-understanding-regex-in-mp3tag/51085/1 "2020-12-08T21:38:56Z")
Hi guys, I studied computer science but I seem to be totally misunderstanding regex in mp3tag. I mean, why is `$regexp(%title%,([a-z])+,_)` with `Drüg (feat. Emie)` producing `_D_r_ü_g_ _(_f_e_a_t_._ _E_m_i_e_)_` ??? I expected `D_ü_ ( ____. E___ )` > `$regexp(x,expr,repl)` replaces the pattern specified by the regular expression `expr` in the string `x` by `repl`. ---
**Author:** ![dano](https://community.mp3tag.de/user_avatar/community.mp3tag.de/dano/32/6_2.png) [@dano](https://community.mp3tag.de/u/dano)\ **Post date:** [December 8, 2020, 9:45pm UTC](https://community.mp3tag.de/t/i-need-help-understanding-regex-in-mp3tag/51085/2 "2020-12-08T21:45:53Z")
You have to keep in mind the provided scripting language has its own syntax and special chars. It is recommended to put especially regex patterns in ' apostrophes so you don't have to escape each ( or [ character. Try `$regexp(%title%,'([a-z])+',_)` ---
**Author:** ![Moibilak7](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/m/3e96dc/32.png) [@Moibilak7](https://community.mp3tag.de/u/Moibilak7)\ **Post date:** [December 8, 2020, 10:06pm UTC](https://community.mp3tag.de/t/i-need-help-understanding-regex-in-mp3tag/51085/3 "2020-12-08T22:06:19Z")
Thanks bud, I will try using apostrophes. ---
**Author:** ![Moibilak7](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/m/3e96dc/32.png) [@Moibilak7](https://community.mp3tag.de/u/Moibilak7)\ **Post date:** [December 8, 2020, 10:09pm UTC](https://community.mp3tag.de/t/i-need-help-understanding-regex-in-mp3tag/51085/4 "2020-12-08T22:09:24Z")
Still no luck... I don't get it. `$regexp(%title%,'([A-Z][a-z]\xdc\xfc\d\s)+',_)` is producing nothing. Shouldn't `([A-Z][a-z]\xdc\xfc\d\s)+` select `Drüg`, `feat` and `Emie`? Afaik `([A-Z][a-z])+` finds every word that consists of uppercase and lowercase letters ranging from a to z. But in mp3tag literally nothing gets found or replaced at all. What am I missing? I am losing my believe in myself. I found the solution... I have to include the | `OR` operator: `$regexp(%title%,'([A-Z]|[a-z])+',_)` Now I can sleep in peace. ---
**Author:** ![dano](https://community.mp3tag.de/user_avatar/community.mp3tag.de/dano/32/6_2.png) [@dano](https://community.mp3tag.de/u/dano)\ **Post date:** [December 8, 2020, 11:29pm UTC](https://community.mp3tag.de/t/i-need-help-understanding-regex-in-mp3tag/51085/5 "2020-12-08T23:29:29Z")
Maybe instead of `$regexp(%title%,'([A-Z][a-z]\xdc\xfc\d\s)+',_)` you meant `$regexp(%title%,'([A-Za-z\xdc\xfc\d\s])+',_)` Understand the difference `[A-Z][a-z]` vs `[A-Za-z]` ---
**Author:** ![Moibilak7](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/m/3e96dc/32.png) [@Moibilak7](https://community.mp3tag.de/u/Moibilak7)\ **Post date:** [December 8, 2020, 11:32pm UTC](https://community.mp3tag.de/t/i-need-help-understanding-regex-in-mp3tag/51085/6 "2020-12-08T23:32:44Z")
The thing is that I tried that and didn't get to the solution I expected either. But I slowly begin to understand. However, thanks for your help. ---
**Author:** ![system](https://community.mp3tag.de/uploads/default/original/2X/c/ce7035d426cb755a7916793326d23b465222a407.png) [@system](https://community.mp3tag.de/u/system)\ **Post date:** [January 7, 2021, 11:32pm UTC](https://community.mp3tag.de/t/i-need-help-understanding-regex-in-mp3tag/51085/7 "2021-01-07T23:32:45Z")
This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.