Regular Expressions 101

^start of line

\d+a Unicode decimal digit, repeated at least once

Non-Capturing Group(?:\.\d+)+

+repeats the group contents below at least once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\d+a Unicode decimal digit, repeated at least once

\ba Unicode word boundary

Group 1(.*)

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

Group 2((?:\n(?!\d+\.\d).*)*)

Non-Capturing Group(?:\n(?!\d+\.\d).*)*

*repeats the group contents below any number of times:

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

Negative Lookahead(?!\d+\.\d)

\d+a Unicode decimal digit, repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\da Unicode decimal digit

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

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

^\d+(?:\.\d+)+\b(.*)((?:\n(?!\d+\.\d).*)*)

New

1.1 Introduction
There are some sentences in here that I want and I want to do other things with them. There could be hundreds of sentences, who cares.
1.1.1 Something Else
This is where we talk about something else in life.
...
5.1.1 Conclusion

Regular Expression

Extraction