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标题: Reference - What does this regex mean? [打印本页]

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作者: 菜鸟教程小白    时间: 2022-4-10 15:37
标题: Reference - What does this regex mean?

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推荐答案

The Stack Overflow Regular Expressions FAQ

See also a lot of general hints and useful links at the regex tag details page.

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Online tutorials

• RegexOne ↪
• Regular Expressions Info ↪

Quantifiers

• Zero-or-more: *:greedy, *?:reluctant, *+:possessive
• One-or-more: +:greedy, +?:reluctant, ++:possessive
• ?ptional (zero-or-one)
• Min/max ranges (all inclusive): {n,m}:between n & m, {n,}:n-or-more, {n}:exactly n
• Differences between greedy, reluctant (a.k.a. "lazy", "ungreedy") and possessive quantifier:
  • Greedy vs. Reluctant vs. Possessive Quantifiers
  • In-depth discussion on the differences between greedy versus non-greedy
  • What's the difference between {n} and {n}?
  • Can someone explain Possessive Quantifiers to me? php, perl, java, ruby
  • Emulating possessive quantifiers .net
  • Non-Stack Overflow references: From Oracle, regular-expressions.info

Character Classes

• What is the difference between square brackets and parentheses?
• [...]: any one character, [^...]: negated/any character but
• [^] matches any one character including newlines javascript
• [\w-[\d]] / [a-z-[qz]]: set subtraction .net, xml-schema, xpath, JGSoft
• [\w&&[^\d]]: set intersection java, ruby 1.9+
• [[:alpha:]]OSIX character classes
• [[:<:]] and [[:>:]] Word boundaries
• Why do [^\\D2], [^[^0-9]2], [^2[^0-9]] get different results in Java? java
• Shorthand:
  • Digit: \d:digit, \D:non-digit
  • Word character (Letter, digit, underscore): \w:word character, \W:non-word character
  • Whitespace: \s:whitespace, \S:non-whitespace
• Unicode categories (\p{L}, \P{L}, etc.)

Escape Sequences

• Horizontal whitespace: \h:space-or-tab, \t:tab
• Newlines:
  • \r, \n:carriage return and line feed
  • \R:generic newline php java-8
• Negated whitespace sequences: \H:Non horizontal whitespace character, \V:Non vertical whitespace character, \N:Non line feed character pcre php5 java-8
• Other: \v:vertical tab, \e:the escape character

Anchors

anchor	matches	flavors
^	Start of string	Common*
^	Start of line	Commonm
$	End of line	Commonm
$	End of text	Common*
$	The very end of string	phpD, javascript
\A	Start of string	Common except js
\Z	End of text	Common except js python
\Z	The very end of string	python
\z	The very end of string	Common except js python
\b	Word boundary	Common
\B	Not a word boundary	Common
\G	End of previous match	Common except js, python re

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