Regular Expressions 101

Pro

^start of line

Positive Lookahead(?=[A-Za-z ]{3,15}$)

Character Class[A-Za-z ]{3,15}

{3,15}matches between 3 and 15 characters 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)

the literal (32₁₀ / 40₈ / 20₁₆)

$end of line

Positive Lookahead(?=[A-Za-z ]*[A-Za-z]{3})

Character Class[A-Za-z ]*

*matches any number of characters 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)

the literal (32₁₀ / 40₈ / 20₁₆)

Character Class[A-Za-z]{3}

{3}matches exactly 3 characters 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)

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

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

\ban ASCII word boundary

Character Class[A-Z]?

?matches at most one character from the set below:

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

Regular Expression

^(?=[A-Za-z ]{3,15}$)(?=[A-Za-z ]*[A-Za-z]{3})(?:\b[A-Z]?[a-z]*\ ?\b){1,3}$

New

Yaw
yaw
James Bond
Monkey D Luffy
List item
Mas few def
Mas no no
No mas no
No no mas
Masa no no
aa Mdef
Jamesbondokskdk
YaW
Two  spaces
No no no
abg def ghi 
JamesBond

Substitution

Yaw
yaw
James Bond
Monkey D Luffy
List item
Mas few def
Mas no no
No mas no
No no mas
Masa no no
aa Mdef
Jamesbondokskdk
YaW
Two  spaces
No no no
abg def ghi 
JamesBond