preg_replace($pattern, $replacement, $subject, $limit = -1, $count = 0);
preg_replace_callback($pattern, $callback, $subject, $limit = -1, $count = 0);
preg_match($pattern, $subject, &$matches, $flags = 0, $offset = 0);
preg_match_all($pattern, $subject, &$matches, $flags = PREG_PATTERN_ORDER, $offset = 0);
preg_split($pattern, $subject, $limit = -1, $flags = 0)
|a string with a regular expression (PCRE pattern)|
PHP regular expressions follow PCRE pattern standards, which are derived from Perl regular expressions.
All PCRE strings in PHP must be enclosed with delimiters. A delimiter can be any non-alphanumeric, non-backslash, non-whitespace character. Popular delimiters are
% for instance.
PCRE patterns can contain groups, character classes, character groups, look-ahead/look-behind assertions and escaped characters.
It is possible to use PCRE modifiers in the
$pattern string. Some common ones are
i (case insensitive),
m (multiline) and
s (the dot metacharacter includes newlines). The
g (global) modifier is not allowed, you will use the
preg_match_all function instead.
Matches to PCRE strings are done with
$ prefixed numbered strings:
<?php $replaced = preg_replace('%hello ([a-z]+) world%', 'goodbye $1 world', 'hello awesome world'); echo $replaced; // 'goodbye awesome world'