Regular Expressions 101

Explanation

Pro

^start of line

Positive Lookahead(?=(?:[a-zA-Z\d][ -]?){2,16}$)

Non-Capturing Group(?:[a-zA-Z\d][ -]?){2,16}

{2,16}repeats the group contents below between 2 and 16 times:

Character Class[a-zA-Z\d]

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

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

\da digit

Character Class[ -]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

$end of line

Positive Lookahead(?=[^\d\n]*\d)

Negated Character Class[^\d\n]*

*matches any number of characters outside the set below:

\da digit

\na line-feed (newline) character (ASCII 10)

\da digit

Character Class[a-zA-Z\d]+

+matches at least one character from the set below:

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

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

\da digit

Non-Capturing Group(?:[ -][a-zA-Z\d]+)?

?repeats the group contents below at most once:

Character Class[ -]

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[a-zA-Z\d]+

+matches at least one character from the set below:

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

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

\da digit

$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.

25 tokens

^(?=(?:[a-zA-Z\d][ -]?){2,16}$)(?=[^\d\n]*\d)[a-zA-Z\d]+(?:[ -][a-zA-Z\d]+)?$

New

test one
test 2two
test3 three222
3test-4four
ex-itshouldpass16

-test
test-d f