Regular Expressions 101

Positive Lookbehind(?<=(?<!\n)\n)

Negative Lookbehind(?<!\n)

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

Positive Lookahead(?=# header$)

# headerthe literal text # header (case sensitive)

$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

(?<=(?<!\n)\n)(?=# header$)

New

# header
I assume do not match above
a = 1
b = 2

# header
do not match above
f = 10
g = 20
# header
match above
x = abc
y = def
within line # header
I assume do not match above

Regular Expression

Extraction