Regular Expressions 101

^start of line

Character Class[\s\S]*

*matches any number of characters from the set below:

\sany whitespace character

\Sany non-whitespace character

Non-Capturing Group(?:^|\r?\n)

1st Alternative^

^start of line

2nd Alternative\r?\n

\r?optionally matches a carriage return (ASCII 13)

\na line-feed (newline) character (ASCII 10)

\s+any whitespace character, repeated at least once

Group 1(\d+)

\d+a digit, repeated at least once

Negative Lookahead(?![\s\S]*(\r?\n){2})

Character Class[\s\S]*

*matches any number of characters from the set below:

\sany whitespace character

\Sany non-whitespace character

Group 2(\r?\n){2}

{2}repeats the group contents below exactly 2 times:

\r?optionally matches a carriage return (ASCII 13)

\na line-feed (newline) character (ASCII 10)

Global pattern flags

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

Regular Expression

^[\s\S]*(?:^|\r?\n)\s+(\d+)(?![\s\S]*(\r?\n){2})

New

this is test
           1. this is test
           2. this is test
              3. this is test
           this is test
           1. this test
                   2. this is test 5
           this is test