Regular Expressions 101

Group 1(\S)

\Sany non-whitespace character

Group 2(\S+)

\S+any non-whitespace character, repeated at least once

\1the text saved by group 1

Positive Lookahead(?=\s|$)

1st Alternative\s

\sany whitespace character

2nd Alternative$

$end of line

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.

Search reference

Regular Expression

(\S)(\S+)\1(?=\s|$)

8This8 is &reallly& a #test# of %repl%acing% %mul%tiple 9matched9 9pairs

$2