Regular Expressions 101

Explanation

Pro

\ban ASCII word boundary

Group 1(\d+)

\d+a digit, repeated at least once

\ban ASCII word boundary

Non-Capturing Group(?:(?<=\b\1\b.*\b\1\b)|(?=.*\b\1\b))

1st Alternative(?<=\b\1\b.*\b\1\b)

Positive Lookbehind(?<=\b\1\b.*\b\1\b)

\ban ASCII word boundary

\1the text saved by group 1

\ban ASCII word boundary

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

\ban ASCII word boundary

\1the text saved by group 1

\ban ASCII word boundary

2nd Alternative(?=.*\b\1\b)

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

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

\ban ASCII word boundary

\1the text saved by group 1

\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.

26 tokens

\b(\d+)\b(?:(?<=\b\1\b.*\b\1\b)|(?=.*\b\1\b))

New

16,17,22,22,22,22,20,16

16,17,22,22,22,22,20,16