Regular Expressions 101

Explanation

Pro

\ban ASCII word boundary

Positive Lookahead(?=[a-zA-Z]*[A-Z])

Character Class[a-zA-Z]*

*matches any number of characters 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)

Character Class[A-Z]

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

Character Class[a-zA-Z]{1,4}

{1,4}matches between 1 and 4 characters 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)

\ban ASCII word boundary

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

\b(?=[a-zA-Z]*[A-Z])[a-zA-Z]{1,4}\b

New

A, Ab, AbC, ABC, Abcd, bACD, aBCd, abcD

Abcd and Hi but not abcd and not abcdefgHI