Regular Expressions 101

Pro

Positive Lookbehind(?<=(.))

Group 1(.)

.any character (except for line terminators)

\1the text saved by group 1

Positive Lookahead(?=\1*(.))

\1*the text saved by group 1, repeated any number of times

Group 2(.)

.any character (except for line terminators)

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

(?<=(.))\1(?=\1*(.))

New

aab
aaab
aaaab
aabaaaaaaabaaabab
aabaaacaaaabaaababbb

$2

aab
aaab
aaaab
aabaaaaaaabaaabab
aabaaacaaaabaaababbb