Regular Expressions 101

Pro

Non-Capturing Group(?:Solution:)?

?repeats the group contents below at most once:

Solution:the literal text Solution: (case sensitive)

\s*any whitespace character, repeated any number of times

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

?repeats the group contents below at most once:

\d+a digit, repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

the literal (32₁₀ / 40₈ / 20₁₆)

Group 1(.+?)

.+?any character, repeated at least once

Positive Lookahead(?=\n(?:Solution:|\d+\. )|\Z)

1st Alternative\n(?:Solution:|\d+\. )

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

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

1st AlternativeSolution:

Solution:the literal text Solution: (case sensitive)

2nd Alternative\d+\.

\d+a digit, repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

the literal (32₁₀ / 40₈ / 20₁₆)

2nd Alternative\Z

\Zend of string, or before its final line terminator

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

s modifier: single line. Allows a dot to match line terminators

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25 tokens

(?:Solution:)?\s*(?:\d+\. )?(.+?)(?=\n(?:Solution:|\d+\. )|\Z)

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