> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kameleoon.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Regular expressions

> Reference for the regular expression syntax Kameleoon supports in the matches the regular expression operator across segments, goals, and advanced targeting tools conditions.

A regular expression is a pattern that matches text against a set of rules instead of a single exact string. Use a regular expression when a condition needs to match multiple variations of a URL, such as different query parameters or page numbers, rather than one exact address.

Kameleoon conditions that offer a **matches the regular expression** operator use the syntax on this page, including segment conditions like Landing page URL and Referring website URL, goal URL conditions, and advanced targeting tools like acquisition channels and key pages.

## Regular expression syntax

* `.` matches any single character. For example, `Kamele.on` matches `Kameleoon`, `Kamele0n`, and `Kamele8on`.
* `*` matches the preceding character zero or more times. For example, `Kameleoo*n` matches `Kameleon`, `Kameleoon`, and `Kameleooon`.
* `?` matches the preceding character zero or one time. For example, `Kameleoo?n` matches `Kameleon` and `Kameleoon`.
* `+` matches the preceding character one or more times. For example, `Kameleo+n` matches `Kameleoon` and `Kameleoooon`.
* `|` acts as an OR operator between two patterns. For example, `Kameleoon|Chameleoon` matches `Kameleoon` or `Chameleoon`.
* `^` matches the start of the string. For example, `^Kameleoon` matches URLs starting with `Kameleoon`.
* `$` matches the end of the string. For example, `Kameleoon$` matches URLs ending with `Kameleoon`.
* `()` groups several elements, usually combined with `|`. For example, `Kameleoon (AB Testing|Conversion) Tool` matches `Kameleoon AB Testing Tool` or `Kameleoon Conversion Tool`.
* `[]` matches any single character inside the brackets. For example, `/Kameleoon/[234]` matches `Kameleoon 2`, `Kameleoon 3`, and `Kameleoon 4`.
* `-` defines a range inside `[]`. For example, `/kameleoon/[2-9]` matches every page from `Kameleoon 2` to `Kameleoon 9`.
* `{}` sets a minimum and maximum number of repetitions of the preceding character. For example, `Kameleo{2,4}n` matches `Kameleoon`, `Kameleooon`, and `Kameleoooon`.

<Note>
  Escape special characters (for example, `,`, `.`, `*`) with a backslash: `\,`, `\.`, `\*`.
</Note>

<Note>
  Regular expressions are case-sensitive.
</Note>

## Examples

* `^.{10}$` matches URLs containing exactly 10 characters.
* `general\.(html|php)$` matches URLs ending with either `general.php` or `general.html`.
* `/fr/` matches URLs containing `/fr/`.
* `/annexes/.*\d{3}` matches URLs containing the fragment `/annexes/` and a three-digit number.
* `/annexes/.*\d{2}.*test.html$` matches URLs containing the fragment `/annexes/`, a two-digit number, and ending with `test.html`.