Sunday, May 31, 2009

PHP Regular Expressions Cheat Sheet

The following should be escaped if you are trying to match that character

\ ^ . $ | ( ) [ ]
* + ? { } ,

Special Character Definitions

  • \ Quote the next metacharacter
  • ^ Match the beginning of the line
  • . Match any character (except newline)
  • $ Match the end of the line (or before newline at the end)
  • | Alternation
  • () Grouping
  • [] Character class
  • * Match 0 or more times
  • + Match 1 or more times
  • ? Match 1 or 0 times
  • {n} Match exactly n times
  • {n,} Match at least n times
  • {n,m} Match at least n but not more than m times
  • More Special Character Stuff
  • \t tab (HT, TAB)
  • \n newline (LF, NL)
  • \r return (CR)
  • \f form feed (FF)
  • \a alarm (bell) (BEL)
  • \e escape (think troff) (ESC)
  • \033 octal char (think of a PDP-11)
  • \x1B hex char
  • \c[ control char
  • \l lowercase next char (think vi)
  • \u uppercase next char (think vi)
  • \L lowercase till \E (think vi)
  • \U uppercase till \E (think vi)
  • \E end case modification (think vi)
  • \Q quote (disable) pattern metacharacters till \E
  • Even More Special Characters
  • \w Match a "word" character (alphanumeric plus "_")
  • \W Match a non-word character
  • \s Match a whitespace character
  • \S Match a non-whitespace character
  • \d Match a digit character
  • \D Match a non-digit character
  • \b Match a word boundary
  • \B Match a non-(word boundary)
  • \A Match only at beginning of string
  • \Z Match only at end of string, or before newline at the end
  • \z Match only at end of string
  • \G Match only where previous m//g left off (works only with /g)
For a more detailed study on Regular Expressions, visit this.

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