Regular Expressions 101

Pro

\ban ASCII word boundary

Negative Lookahead(?![a-z]*([a-z])([a-z])\2\1[a-z]*\b)

Character Class[a-z]*

*matches any number of characters from the set below:

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

Group 1([a-z])

Character Class[a-z]

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

Group 2([a-z])

Character Class[a-z]

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

\2the text saved by group 2

\1the text saved by group 1

Character Class[a-z]*

*matches any number of characters from the set below:

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

\ban ASCII word boundary

Character Class[a-z]+

+matches at least one character from the set below:

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

\ban ASCII word boundary

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

\b(?![a-z]*([a-z])([a-z])\2\1[a-z]*\b)[a-z]+\b

New

This is a regex that matches everything i want to exclude, which is words like abba, trillion

This is a regex that matches everything i want to exclude, which is words like abba, trillion