Symbols

!~ operator, Perl

# character, Free-spacing mode, Variations, Discussion

escaping, Discussion

for comments, Free-spacing mode, Variations

$ token, Anchors and lines–Variations, End of a line, End of a line, Variations, Regular expression syntax, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion

as anchor, Anchors and lines–Variations, Discussion, Discussion, Discussion, Discussion, Discussion

for multiple lines, End of a line, Discussion

in JavaScript, Discussion

in Perl, Discussion

in Ruby, End of a line, Variations, Discussion

vs.  token, Regular expression syntax, Discussion, Discussion, Discussion

$& variable, Discussion, Ruby, Perl, Perl, Discussion

$' token, Discussion, Discussion, Perl and Ruby

$10 and higher groups, $10 and higher–$10 and higher

$_ token, Discussion, Perl, Perl, Perl, Perl, PHP, Perl

$` (dollar backtick) token, Discussion, Discussion, Perl and Ruby, Perl and Ruby

$~ variable, Ruby, Ruby, Ruby, Ruby, Ruby, Ruby

%+ hash (Perl), Perl, Perl

%r prefix (Ruby), Ruby

(?!) for empty negative lookahead, Discussion, The ugly solution

(?!...) for negative lookahead, Introduction to Regular Expressions (see lookaheads)

(?#...), Variations, Variations

(?&name) for subroutines, Using a conditional

(?(if)then|else) for conditionals, Introduction to Regular Expressions (see conditionals)

(?-flags) for mode modifier, Case-insensitive matching, Variations, Group with mode modifiers, Group with mode modifiers

(?:...) for noncapturing groups, Noncapturing groups (see noncapturing groups)

(?<!...) for negative lookbehind, Introduction to Regular Expressions (see lookbehinds)

(?<=...) for positive lookbehind, Lookaround (see lookbehinds)

(?<name>...) for named capture, Introduction to Regular Expressions (see named capturing groups)

(?=...) for positive lookahead, Solution, Lookaround (see lookaheads)

(?>...) for atomic groups, Discussion (see atomic groups)

(?i) mode modifier, Case-insensitive matching, Case-insensitive matching, Case insensitivity, Group with mode modifiers, Java

(?m) mode modifier, Regex Flavors Covered by This Book, Variations, Variations, Variations, Variations, Variations, Variations, Word boundaries

(?n) mode modifier, .NET

(?P=name) for named backreferences, Named backreferences, Named backreferences

(?s) mode modifier, Regex Flavors Covered by This Book, Variations

(?x) mode modifier, Variations, Variations

* quantifier, Discussion, Regular expression syntax, Words ending with “phobia”, Problem, Discussion, Allow > in attribute values, Discussion

*+ quantifier, Discussion

*? quantifier, Discussion, Variations, How it works, Two-step approach–Single-step approach

+ quantifier, Regular expression syntax, Discussion, Discussion, Discussion, Option 1: Sort lines and remove adjacent duplicates, Clean any whitespace characters, Use infinite lookbehind, Discussion, (X)HTML tags (strict), Discussion

and backtracking, Discussion

greedy vs. lazy use, Discussion

in lookbehind, Use infinite lookbehind

making possessive, (X)HTML tags (strict)

++ quantifier, Discussion

+? quantifier, Discussion

- character, Discussion, Discussion

. (dot) metacharacter, Match Any Character–See Also, Match Any Character–See Also, Problem–Any character except line breaks, Problem–Any character including line breaks, Dot abuse–Dot abuse, Discussion, Discussion

abuse of, Dot abuse–Dot abuse

matching any character with, Match Any Character–See Also, Problem–Any character except line breaks, Problem–Any character including line breaks

except line breaks, Problem–Any character except line breaks

including line breaks, Problem–Any character including line breaks

/a flag, Shorthands, Word Characters, Perl

/d flag, Shorthands, Word Characters, Perl

/e flag, Ruby, Perl, Perl

/g flag, RegexRenamer, JavaScript, JavaScript, Perl, Example JavaScript solution, Example JavaScript solution

/i flag, RegexRenamer, Case insensitivity, JavaScript, Ruby, Ruby, Ruby

/l flag, Shorthands, Word Characters, Perl

/m flag, JavaScript, Ruby, Ruby, Ruby, Ruby, JavaScript, JavaScript, JavaScript, Discussion, Discussion

/n flag, Ruby

/o flag, Perl

/r flag, Ruby

/s flag, Ruby, Ruby, Ruby

/u flag, Shorthands, Word Characters, PHP, Limit input to alphanumeric characters in any language, XML 1.0 names (approximate)

/U flag, PHP, PHP, PHP, PHP

/x flag, RegexRenamer, Free-spacing mode, PHP, Perl, Ruby

7-bit character set, The 7-bit character set–The 7-bit character set

<< operator, Discussion

<b>, replacing with <strong>, Problem–See Also

<strong>, replacing <b> with, Problem–See Also

=~ operator, More Programming Languages, Ruby, Ruby, Perl

? quantifier, Discussion, Color or colour, Problem, Variations, (X)HTML tags (strict)

?+ quantifier, Discussion

@ character, Perl, Simple, Simple, with restrictions on characters

[ character, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion, Solution, Discussion

[sS], Length between 8 and 32 characters, Discussion, Variations, Discussion, Outer regex for (X)HTML, How it works

[] token for empty character class, Discussion

(escape character), Problem, Discussion

for escape sequences, Discussion

& token, Discussion, Discussion, Discussion

' token, Discussion

a token, Discussion

A token, Anchors and lines, Start of the subject, Zero-length matches, Ruby, C# and VB.NET, .NET, Discussion, Discussion, Discussion

zero-length matches, .NET

 token, Shorthands, Word boundaries, Nonboundaries, Nonboundaries, Word Characters, Discussion, .NET, Find phone numbers in documents, Limit the number of words, Validate the number, Discussion, Fixed, finite, and infinite length lookbehind, Variations, Discussion, Discussion, Discussion, Discussion, Single-step approach

and special characters, Variations

and U flag, Discussion

in Java, Limit the number of words

in lookbehind, Fixed, finite, and infinite length lookbehind

vs. B token, Nonboundaries, Nonboundaries

B token, Nonboundaries, Nonboundaries, Word Characters, Word Characters

cH token, The 26 control characters

d token, Shorthands, Discussion, Python, Discussion, Numbers

D token, Shorthands, Shorthands, Strip spaces and hyphens

E token, Block escape, Block escape, Block escape, Variations

e token, Discussion

f token, Discussion, Working with esoteric line separators

h token, Discussion, Clean horizontal whitespace characters

K token, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Alternative to Lookbehind, Variations, Variations, Variations, See Also, Discussion, Discussion, Discussion, See Also

token, Conventions Used in This Book, Discussion, Free-spacing mode, C#, C#, C#, C#, Java, Java, Python, Python, Python, Python, Java, Discussion, Limit input to ASCII noncontrol characters and line breaks, Drive letter paths, Example JavaScript solution

in C#, C#, C#, C#, C#

in Java, Java, Java

in Python, Python, Python, Python, Python

p token, Java character class union, intersection, and subtraction, Unicode category, Unicode category, Negated variant, Negated variant, Character classes

P token, Unicode category, Negated variant, Negated variant, Character classes

p{Ll} token, Unicode category, Unicode category, Unicode category

P{Lu} token, Unicode category

p{L} token, Shorthands, Unicode category, One or more uppercase letters, Discussion, Variations, Variations, XML 1.0 names

P{L} token, Unicode category

P{N} token, .NET character class subtraction

p{N} token, Java character class union, intersection, and subtraction, Matching the same text twice, Matching the same text twice, Matching the same text twice, Matching the same text twice

p{Z} token, Limit the number of nonwhitespace characters, Limit the number of nonwhitespace characters, Limit the number of nonwhitespace characters

Q token, Block escape, Block escape, Block escape

token, Conventions Used in This Book, Discussion, Limit input to ASCII noncontrol characters and line breaks, Discussion, Working with esoteric line separators, Drive letter paths

R token, Step 2: Replace all line breaks with <br>, See Also, See Also

? , Discussion, Variations

, Conventions Used in This Book, Free-spacing mode, Discussion, Discussion, Working with esoteric line separators

s token, Shorthands, Shorthands, Any character including line breaks, Any character including line breaks, Python, Limit the number of nonwhitespace characters, Discussion, Clean any whitespace characters, How it works

in Python, Python

regex flavor differences, Limit the number of nonwhitespace characters, Discussion

using with S token, How it works

vs. S token, Any character including line breaks, Any character including line breaks

S token, Shorthands, Any character including line breaks, Any character including line breaks, Regular expression syntax, Variations, Discussion, How it works

using with s token, How it works

vs. s token, Any character including line breaks, Any character including line breaks

token, Discussion, Free-spacing mode

u token, Unicode code point, Character classes

U token, Unicode code point, XML 1.1 names (exact)

v token, Discussion, Discussion, Discussion, Working with esoteric line separators

w token, Shorthands, Shorthands, Word Characters, .NET, Python, Discussion, Discussion, Variations, Discussion

and U flag, Discussion

in .NET, .NET

in Python, Python

W token, Shorthands, Word boundaries, Limit input to alphanumeric characters in any language, Discussion, Discussion

x token, The 7-bit character set, Character classes

X token, See Also, Unicode grapheme, Unicode grapheme, Unicode grapheme, Unicode grapheme

z token, Anchors and lines, End of the subject, End of the subject, End of the subject, End of the subject, End of the subject, End of the subject, Solution Without Lookbehind, Regular expression–Discussion

 token, End of the subject, Zero-length matches, Ruby, Discussion, Regular expression syntax, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion

in JavaScript, Regular expression syntax, Discussion, Discussion

in Ruby, Ruby, Discussion, Discussion

vs. $ token, Discussion, Discussion

` token, Discussion

^ token, Anchors and lines, Start of the subject–Variations, Regular expression syntax, Regular expression syntax, Discussion, Limit the length of an arbitrary pattern, Discussion, Option 1: Sort lines and remove adjacent duplicates, Discussion, Discussion, Discussion, Discussion, Discussion, Discussion

and lookahead, Limit the length of an arbitrary pattern

in Ruby, Start of the subject–Variations, Regular expression syntax, Discussion, Discussion

multiple uses of, Discussion

regex flavor differences, Discussion

regex options for, Option 1: Sort lines and remove adjacent duplicates, Discussion

{ character, Discussion, Discussion

| token, Problem–See Also, Discussion, Using alternation, (X)HTML tags (loose), Replace a list of tags, Discussion