Regular Expressions 101

Pro

^start of line

Negative Lookahead(?!.{16})

.{16}any character (except for line terminators), repeated exactly 16 times

Positive Lookahead(?=.*?\S{3})

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

\S{3}any non-whitespace character, repeated exactly 3 times

Non-Capturing Group(?:[A-Za-z][a-z]* ?\b){1,3}

{1,3}repeats the group contents below between 1 and 3 times:

Character Class[A-Za-z]

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

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

Character Class[a-z]*

*matches any number of characters from the set below:

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

?optionally matches the literal (32₁₀ / 40₈ / 20₁₆)

\ban ASCII word boundary

$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

^(?!.{16})(?=.*?\S{3})(?:[A-Za-z][a-z]* ?\b){1,3}$

New

Should match:

Yaw
yaw
James Bond
Monkey D Luffy
List item

Shouldn't match:

YaW
Two  spaces
No no no
JamesBond

Should match:

Yaw
yaw
James Bond
Monkey D Luffy
List item

Shouldn't match:

YaW
Two  spaces
No no no
JamesBond