Regular Expression Pocket Reference, 2nd Edition

Supported Metacharacters

PHP supports the metacharacters and metasequences listed in Table 22 through Table 26. For expanded definitions of each metacharacter, see "Regex Metacharacters, Modes, and Constructs.”

Table 1-22. PHP character representations

Sequence	Meaning
\a	Alert (bell), \x07.
\b	Backspace, \x08, supported only in character class.
\e	Esc character, \x1B.
\n	Newline, \x0A.
\r	Carriage return, \x0D.
\f	Form feed, \x0C.
\t	Horizontal tab, \x09.
\octal	Character specified by a three-digit octal code.
\xhex	Character specified by a one- or two-digit hexadecimal code.
\x{hex}	Character specified by any hexadecimal code.
\cchar	Named control character.

Table 1-23. PHP character classes and class-like constructs

Class	Meaning
[...]	A single character listed or contained within a listed range.
[^...]	A single character not listed and not contained within a listed range.
[:class:]	POSIX-style character class (valid only within a regex character class).
.	Any character except newline (unless single-line mode, /s).
\C	One byte (this might corrupt a Unicode character stream, however).
\w	Word character, [a-zA-z0-9_].
\W	Nonword character, [^a-zA-z0-9_].
\d	Digit character, [0-9].
\D	Nondigit character, [^0-9].
\s	Whitespace character, [\n\r\f\t ].
\S	Nonwhitespace character, [^\n\r\f\t ].

Table 1-24. PHP anchors and zero-width tests

Sequence	Meaning
^	Start of string, or the point after any newline if in multiline match mode, /m.
\A	Start of search string, in all match modes.
$	End of search string, or the point before a string-ending ...