# Regular Expressions

**URL:** <https://community.mp3tag.de/t/regular-expressions/521>\
**Category:** Howto\
**Created:** [October 16, 2003, 4:47pm UTC](https://community.mp3tag.de/t/regular-expressions/521 "2003-10-16T16:47:29Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![mll](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/m/6a8cbe/32.png) [@mll](https://community.mp3tag.de/u/mll)\
**Post date:** [July 14, 2004, 7:27am UTC](https://community.mp3tag.de/t/regular-expressions/521/7 "2004-07-14T07:27:08Z")

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Used to use this basic regexp :

Applied on TRACK, find ^(\d)$ and replace by 0$1

It adds a leading 0 to the track number. I was thinking about enhancing it to apply it only to 1-digit numbers... when I discovered Ctrl+K 🙂 :

Cheers,

MLL

According to RevRagnarok's suggestions below, I've made the expression less greedy

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