Regular Expressions 101

Pro

^start of line

Group 1(subject\s+name="(?:Biology|chem102)".*(?:\n(?!subject\s|topic$).*)*\n)

subjectthe literal text subject (case sensitive)

\s+a Unicode whitespace character, repeated at least once

name="the literal text name=" (case sensitive)

Non-Capturing Group(?:Biology|chem102)

1st AlternativeBiology

Biologythe literal text Biology (case sensitive)

2nd Alternativechem102

chem102the literal text chem102 (case sensitive)

"the literal " (34₁₀ / 42₈ / 22₁₆)

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

Non-Capturing Group(?:\n(?!subject\s|topic$).*)*

*repeats the group contents below any number of times:

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

Negative Lookahead(?!subject\s|topic$)

1st Alternativesubject\s

subjectthe literal text subject (case sensitive)

\sa Unicode whitespace character

2nd Alternativetopic$

topicthe literal text topic (case sensitive)

$end of line

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

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

topicthe literal text topic (case sensitive)

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

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25 tokens

^(subject\s+name="(?:Biology|chem102)".*(?:\n(?!subject\s|topic$).*)*\n)topic

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