Regular Expressions 101

Explanation

Pro

^start of line

Positive Lookahead(?=.{3,30}$)

.{3,30}any character (except for line terminators), repeated between 3 and 30 times

$end of line

Character Class[A-Za-z0-9]+

+matches at least one character from the set below:

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)

Non-Capturing Group(?:\s[A-Za-z0-9]+)?

?repeats the group contents below at most once:

\sany whitespace character

Character Class[A-Za-z0-9]+

+matches at least one character from the set below:

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)

$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

^(?=.{3,30}$)[A-Za-z0-9]+(?:\s[A-Za-z0-9]+)?$

New

Mark Twain
Michael Smith
New Name9012345678901234567890
New Name90123456789012345678901

Mark Twain
Michael Smith
New Name9012345678901234567890
New Name90123456789012345678901