Regular Expressions 101

Pro

Negative Lookbehind(?<![A-Z0-9])

Character Class[A-Z0-9]

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

0-9one character from 0 (48₁₀) to 9 (57₁₀)

@the literal @ (64₁₀ / 100₈ / 40₁₆)

Group 1([A-Z][A-Z0-9_]*[A-Z0-9])

Character Class[A-Z]

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

Character Class[A-Z0-9_]*

*matches any number of characters from the set below:

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

0-9one character from 0 (48₁₀) to 9 (57₁₀)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Character Class[A-Z0-9]

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

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Detailed match information will be displayed here automatically.

25 tokens

(?<![A-Z0-9])@([A-Z][A-Z0-9_]*[A-Z0-9])

Accept and return @something but reject first@last.

Accept and return @something but reject first@last.