Regular Expressions 101

Pro

^start of line

Negative Lookahead(?!.*([A-Za-z])\1\1)

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

Group 1([A-Za-z])

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)

\1the text saved by group 1

Negative Lookahead(?!.*\b([A-Za-z]+)\b.*\2)

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

\ban ASCII word boundary

Group 2([A-Za-z]+)

Character Class[A-Za-z]+

+matches at least one character 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)

\ban ASCII word boundary

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

\2the text saved by group 2

.+any character (except for line terminators), repeated at least once

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

^(?!.*([A-Za-z])\1\1)(?!.*\b([A-Za-z]+)\b.*\2).+

New

aabc
aaabc
aabc aabc
aabcde
abs cdd ert fgg fgy df