RegEx

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Notes for RegEx respectively Regular Expressions.

Guide (german): https://t3n.de/news/regex-guide-t3n-552858/

Quick Start Cheat Sheet: https://www.rexegg.com/regex-quickstart.html

Advanced tutorial: https://www.rexegg.com/regex-disambiguation.html

Practical tutorial: https://regexone.com/

Regex with JavaScript: https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/#regular-expressions

Test Regex: https://regexr.com/

General Rules

Character Types
Type Example
Literal a b c 1 2 3
Meta characters . [[ ] { } ? * + | ( ) ^ $


Meaning of meta characters
Meta Character Example
Single Character .
Character class digit \d
Character class character \w
Character class whitespace \s
Inversion of character classes (Not) \D, \W, \S
Character class range [a-c]
Inversion of character class range [^abc]
Grouping with alternatives (Mon|Tues)day
Word and text boundaries b ^ $


Quantifier
Quantifiers Example
Zero or one character ?
Zero or more characters *
One or more characters +
Three characters {3}
Four to 20 characters {4,20}