Regular Expressions 101

^start of line

Character Class[Hh]

Hthe literal H (72₁₀ / 110₈ / 48₁₆) (case sensitive)

hthe literal h (104₁₀ / 150₈ / 68₁₆) (case sensitive)

eadingthe literal text eading (case sensitive)

\ta tab character (ASCII 9)

Group 1(\d+)

\d+a digit, repeated at least once

\ta tab character (ASCII 9)

Character Class[\d\.]+

+matches at least one character from the set below:

\da digit

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\ta tab character (ASCII 9)

Group 2(.+)

.+any character (except for line terminators), repeated at least once

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

^[Hh]eading\t(\d+)\t[\d\.]+\t(.+)

Test String
New

heading	1	0.	References
heading	1	1.	Introduction
heading	1	2.	System of interest: heavy component
heading	2	2.1	Definition and role of the heavy component
heading	3	2.1.1	General Definitions
heading	3	2.1.2	heavy component main missions
heading	11	2.1.1.11.3.4	Generic chapter

Regular Expression

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