Anchors

Anchros

  • ^
  • Start of string, or start of line in multi-line pattern
  • \>
  • End of word
  • \<
  • Start of word
  • \A
  • Start of string
  • \b
  • Word boundary
  • \Z
  • End of string
  • $
  • End of string, or end of line in multi-line pattern

Quantifiers

Quantifiers

Character

Character Classes

  • \c
  • Control character
  • \d
  • Digit
  • \O
  • Octal digit
  • \s
  • White space
  • \w
  • Word
  • \x
  • Hexade-cimal digit

Special

  • \f
  • Form feed
  • \n
  • New line
  • \r
  • Carriage return
  • \t
  • Tab
  • \v
  • Vertical tab
  • \xhh
  • Hex character hh
  • \xxx
  • Octal character xxx

Examples

Metacharacter

Sample

POSIX

POSIX

Groups

Groups and Ranges

  • .
  • Any character except new line (\n)
  • (?:...)
  • Passive (non-c-apt-uring) group
  • (...)
  • Group
  • (a|b)
  • a or b
  • [^abc]
  • Not a or b or c
  • [0-7]
  • Digit from 0 to 7
  • [a-q]
  • Letter from a to q
  • [abc]
  • Range (a or b or c)

Modifiers

Modifiers

  • e
  • Evaluate replac-ement
  • g
  • Global match
  • i
  • Case-i-nse-nsitive
  • m
  • Multiple lines
  • s
  • Treat string as single line
  • U
  • Ungreedy pattern
  • x
  • Allow comments and white space in pattern

String

Replacement

  • $`
  • Before matched string
  • $'
  • After matched string
  • $&
  • Entire matched string
  • $+
  • Last matched string
  • $1
  • "-xyz-" in /^(?:a-bc)-(xyz)$/
  • $2
  • "-xyz-" in /^(abc-(xy-z))$/
  • $n
  • nth non-pa-ssive group

Assertions

Assertions

  • ?!
  • Negative lookahead
  • ?!= or ?<!
  • Negative lookbehind
  • ?()
  • Condition [if then]
  • ?()|
  • Condition [if then else]
  • ?>
  • Once-only Subexp-ression
  • ?<=
  • Lookbehind assertion
  • ?#
  • Comment
  • ?=
  • Lookahead assertion