Regex

Tool zum Testen von Regex-Mustern:
regex101.com

Regex Quickreference

## Grundlagen
.       - Beliebiges Zeichen außer Zeilenumbruch
^       - Anfang der Zeile
$       - Ende der Zeile
*       - 0 oder mehr Wiederholungen
+       - 1 oder mehr Wiederholungen
?       - 0 oder 1 Wiederholung
{n}     - Genau n Wiederholungen
{n,}    - Mindestens n Wiederholungen
{n,m}   - Zwischen n und m Wiederholungen
|       - Oder (z.B. `a|b` matcht "a" oder "b")
()      - Gruppierung (subpatterns)
[]      - Zeichenklasse (z.B. `[a-z]` für Kleinbuchstaben)

## Häufig verwendete Zeichenklassen
\d      - Ziffern (0-9)
\D      - Keine Ziffern
\w      - Wortzeichen (a-z, A-Z, 0-9, _)
\W      - Kein Wortzeichen
\s      - Leerraum (Leerzeichen, Tab, Zeilenumbruch)
\S      - Kein Leerraum

Basic Regex

Basic Regex	Operator	Meaning
Period operator	.	Matches any one single character.
List operator	[ ][^ ]	Defines a list or range of literal characters that can match one character. If the first character is the negation ^ operator, it matches any character that is not in the list.
Asterisk operator	*	Matches zero or more instances of the previous character.
Front anchor operator	^	If ^ is the first character in the pattern, then the entire pattern must be present at the beginning of the line to match. If ^ is not the first character, then it is treated as an ordinary literal ^ character.
Back anchor operator	$	If $ is the last character in the pattern, then the pattern must be at the end of the line to match, otherwise, it is treated as a literal $ character.

Extended Regex

Extended Regex	Operators	Meaning
Grouping operator	( )	Groups characters together to form a subpattern.
Asterisk operator	*	Previous character (or subpattern) is present zero or more times.
Plus operator	+	Previous character (or subpattern) is present at least one or more times.
Question mark operator	?	Previous character (or subpattern) is present zero or one time (but not more).
Curly brace operator	{,}	Specify minimum, maximum, or exact matches of the previous character (or subpattern).
Alternation operator	|	Logical OR of choices. For example, abc|def|xyz matches abc or def or xyz.

Subpatterns ()

Pattern	Meaning
xyz+	Matches the xy string followed by one or more of the z character
(xyz)+	Matches one or more copies of the xyz string
xyz?	Matches the xy string followed by zero or one of the z character
x(yz)?	Matches the x character followed by zero or one of the yz string

OR |

Pattern	Meaning
abc|xyz	Matches the abc string or the xyz string
ab(c|d|e) / ab[cde]	Matches the ab string followed by a c or d or e character

Character Classes

Character	Legend	Example	Sample Match
[ … ]	One of the characters in the brackets	[AEIOU]	One uppercase vowel
[ … ]	One of the characters in the brackets	T[ao]p	Tap or Top
-	Range indicator	[a-z]	One lowercase letter
[x-y]	One of the characters in the range from x to y	[A-Z]+	GREAT
[ … ]	One of the characters in the brackets	[AB1-5w-z]	One of either: A,B,1,2,3,4,5,w,x,y,z
[x-y]	One of the characters in the range from x to y	[ -~]+	Characters in the printable section of the ASCII table.
[^x]	One character that is not x	[^a-z]3	A1!
[^x-y]	One of the characters not in the range from x to y	[^ -~]+	Characters that are not in the printable section of the ASCII table.
[\d\D]	One character that is a digit or a non-digit	[\d\D]+	Any characters, including new lines, which the regular dot doesn't match
[\x41]	Matches the character at hexadecimal position 41 in the ASCII table, i.e. A	[\x41-\x45]3	ABE

Characters

Character	Legend	Example	Sample Match
\d	Most engines: one digit from 0 to 9	file_\d\d	file_25
\d	.NET, Python 3: one Unicode digit in any script	file_\d\d	file_9੩
\w	Most engines: "word character": ASCII letter, digit or underscore	\w-\w\w\w	A-b_1
\w	.Python 3: "word character": Unicode letter, ideogram, digit, or underscore	\w-\w\w\w	字-ま_۳
\w	.NET: "word character": Unicode letter, ideogram, digit, or connector	\w-\w\w\w	字-ま‿۳
\s	Most engines: "whitespace character": space, tab, newline, carriage return, vertical tab	a\sb\sc	a b c
\s	.NET, Python 3, JavaScript: "whitespace character": any Unicode separator	a\sb\sc	a b c
\D	One character that is not a digit as defined by your engine's \d	\D\D\D	ABC
\W	One character that is not a word character as defined by your engine's \w	\W\W\W\W\W	*-+=)
\S	One character that is not a whitespace character as defined by your engine's \s	\S\S\S\S	Yoyo

Quantifiers

Quantifier	Legend	Example	Sample Match
+	One or more	Version \w-\w+	Version A-b1_1
{3}	Exactly three times	\D{3}	ABC
{2,4}	Two to four times	\d{2,4}	156
{3,}	Three or more times	\w{3,}	regex_tutorial
*	Zero or more times	ABC*	AAACC
?	Once or none	plurals?	plu

Häufig verwendete Muster

### 1. Email-Adresse
`[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}`  
✅ `test.email@domain.com`  
❌ `test.email@domain,com`  

### 2. URL
`https?://[^\s/$.?#].[^\s]*`  
✅ `https://example.com`  
✅ `http://sub.domain.net/path?query=1`  

### 3. Dateipfad (Windows)
`[a-zA-Z]:\\(?:[^<>:"/\\|?*]+\\)*[^<>:"/\\|?*]*`  
✅ `C:\Users\Name\file.txt`  
❌ `C:/Users/Name/file.txt`  

### 4. Dateipfad (Linux/Mac)
`(/[^/\0]+)+/?`  
✅ `/home/user/file.txt`  
❌ `home/user/file.txt`  

### 5. IPv4-Adresse
`\b(?:\d{1,3}\.){3}\d{1,3}\b`  
✅ `192.168.1.1`  
❌ `999.999.999.999`  

### 6. Telefonnummer (DE)
`(?:\+49|0)[1-9][0-9]{9,10}`  
✅ `+4917612345678`  
✅ `017612345678`  

### 7. Postleitzahl (DE)
`\b\d{5}\b`  
✅ `10115`  
❌ `1234`  

### 8. JSON-Formatierung prüfen
`\{(?:[^{}]|(?R))*\}`  
✅ `{"key": "value"}`  
❌ `{"key": "value"` 
(fehlt `}`)  

### 9. HTML-Tags entfernen
`<[^>]+>` → Ersetzen durch `""`  
✅ `<p>Hello</p>` → `Hello`  

### 10. Leerzeilen entfernen
`^\s*$` → Ersetzen durch `""`  

Anwendungsbeispiele

Email-Adresse prüfen (Python)

import re

email = "test.email@domain.com"
pattern = r"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$"

if re.match(pattern, email):
    print("✅ Gültige Email")
else:
    print("❌ Ungültige Email")

URL aus einem Text extrahieren (Python)

import re

text = "Besuche meine Seite: https://example.com und http://test.de"
pattern = r"https?://[^\s/$.?#].[^\s]*"

urls = re.findall(pattern, text)
print("Gefundene URLs:", urls)

Windows Dateipfad prüfen (Bash)

echo "C:\Users\Name\file.txt" | grep -E "^[a-zA-Z]:\\(?:[^<>:\"/\\|?*]+\\)*[^<>:\"/\\|?*]*$"

Linux Dateipfad prüfen (Bash)

echo "/home/user/file.txt" | grep -E "^(/[^/\0]+)+/?$"

IPv4-Adresse validieren (JavaScript)

const ipPattern = /\b(?:\d{1,3}\.){3}\d{1,3}\b/;
const ip = "192.168.1.1";

if (ipPattern.test(ip)) {
    console.log("✅ Gültige IP");
} else {
    console.log("❌ Ungültige IP");
}

Telefonnummer bereinigen (DE - Python)

import re

number = "Meine Nummer ist +49 176 12345678"
pattern = r"(?:\+49|0)[1-9][0-9]{9,10}"
match = re.search(pattern, number)

if match:
    print("Gefundene Nummer:", match.group())

Postleitzahlen filtern (Bash)

echo "Berlin 10115" | grep -Eo "\b\d{5}\b"

JSON-String validieren (Python)

import json

data = '{"name": "Max", "age": 25}'
try:
    json.loads(data)
    print("✅ Gültiges JSON")
except json.JSONDecodeError:
    print("❌ Ungültiges JSON")

HTML-Tags entfernen (Python)

import re

html = "<p>Hello <b>World</b></p>"
clean_text = re.sub(r"<[^>]+>", "", html)
print(clean_text)  # Output: Hello World

Leerzeilen aus Datei entfernen (Bash)

sed '/^\s*$/d' input.txt > output.txt

🔥 Zusätzliche Tipps:

Python: re.search() gibt das erste Vorkommen zurück, re.findall() alle Treffer.
JavaScript: .match() gibt Treffer zurück, .replace() kann direkt ersetzen.
Bash: grep -E für erweiterte Regex, sed für Ersetzungen.