Regular Expressions 101

^start of line

Negative Lookahead(?!\s)

\sany whitespace character

Negative Lookahead(?!.*\s\s)

.*any character (except for line terminators), repeated any number of times

\sany whitespace character

Character Class[ A-Za-z0-9'-]{1,35}

{1,35}matches between 1 and 35 characters from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

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

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

'the literal ' (39₁₀ / 47₈ / 27₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Negative Lookbehind(?<! )

the literal (32₁₀ / 40₈ / 20₁₆)

$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.

Search reference

Regular Expression

^(?!\s)(?!.*\s\s)[ A-Za-z0-9'-]{1,35}(?<! )$

def  def
def def