Regular Expressions 101

Pro

1st Alternative((?=^(?:[A-Z][a-z]*[ \t]*)+$).*(?:\n\n|\n?\Z))

Group 1((?=^(?:[A-Z][a-z]*[ \t]*)+$).*(?:\n\n|\n?\Z))

Positive Lookahead(?=^(?:[A-Z][a-z]*[ \t]*)+$)

^start of line

Non-Capturing Group(?:[A-Z][a-z]*[ \t]*)+

+repeats the group contents below at least once:

Character Class[A-Z]

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Character Class[a-z]*

*matches any number of characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Character Class[ \t]*

*matches any number of characters from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

\ta tab character (ASCII 9)

$end of line

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

Non-Capturing Group(?:\n\n|\n?\Z)

1st Alternative\n\n

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

2nd Alternative\n?\Z

\n?optionally matches a line-feed (newline) character (ASCII 10)

\Zend of string

2nd Alternative([\s\S]*?(?=^(?:[A-Z][a-z]*[ \t]*)+$))

Group 2([\s\S]*?(?=^(?:[A-Z][a-z]*[ \t]*)+$))

Character Class[\s\S]*?

*?matches any number of characters from the set below:

\sa Unicode whitespace character

\Sany character that is not Unicode whitespace

Positive Lookahead(?=^(?:[A-Z][a-z]*[ \t]*)+$)

^start of line

Non-Capturing Group(?:[A-Z][a-z]*[ \t]*)+

+repeats the group contents below at least once:

Character Class[A-Z]

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Character Class[a-z]*

*matches any number of characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Character Class[ \t]*

*matches any number of characters from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

\ta tab character (ASCII 9)

$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.

25 tokens

Regular Expression

((?=^(?:[A-Z][a-z]*[ \t]*)+$).*(?:\n\n|\n?\Z))|([\s\S]*?(?=^(?:[A-Z][a-z]*[ \t]*)+$))

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