Regular Expressions

Resourses

rexegg
regex101

Quantifiers

*: 0 or more +: 1 or more ?: 0 or 1 {3}: exact number {3,4}: range of numbers (minimum, maximum)

Special characters

.: any character except new line \d: digit (0-9) \D: not a digit (0-9) \w: word character (a-z, A-Z, 0-9, _) \W: not a word character \s: whitespace (space, tab, newline) \S: not whitespace (space, tab, newline) \b: word boundary \B: not a word boundary

Anchors

^: beginning of string $: end of string

Character sets

[]: matches characters in brackets [^ ]: matches characters NOT in brackets |: either or

Capture groups

( ): group

Back referencing

Positive / Negative Look-ahead / Look-behind

Examples

email:
[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+