> For the complete documentation index, see [llms.txt](https://notes.d15r.de/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://notes.d15r.de/dev/regular-expressions.md).

# Regular-expressions

## Used Expressions

### New Line

matches any Unicode newline sequence; can be modified using verbs

```php
$string = preg_replace('/\R/u', '[,nL]', $string); // Probleme mit Umlauten
$string = preg_replace("/\r|\n/s", '[,nL]', $string);
```

## Tools

* [grex](https://github.com/pemistahl/grex)

## Links

* [regex101](https://regex101.com/) for testing
* [phprex](https://phphub.net/regex/) for testing and visualizing
* [iHateRegex](https://ihateregex.io/)
* [Learn Regex the easy way](https://github.com/ziishaned/learn-regex/blob/master/translations/README-de.md)