Regular Expressions 101

^start of line

Positive Lookahead(?=.{1,50}$)

.{1,50}any character (except for line terminators), repeated between 1 and 50 times

$end of line

Character Class[a-z0-9]+

+matches at least one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Non-Capturing Group(?:[-_\/][a-z0-9]+)*

*repeats the group contents below any number of times:

Character Class[-_\/]

-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Character Class[a-z0-9]+

+matches at least one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[-_\/]?

?matches at most one character from the set below:

-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

26 tokens

Regular Expression

^(?=.{1,50}$)[a-z0-9]+(?:[-_\/][a-z0-9]+)*[-_\/]?$

New

hello
123hello
hello/world
hello_world
hello-world
hello-world/apple
hello_world/apple
hello_world/apple123

helloWorld
-hello
_hello
$hello
/hello
hello$


hello_world/-apple
hello_world/_apple
hello_world//apple

hello_
hello-
hello/

Regular Expression

Extraction