Úvod
The syntax for patterns used in these functions closely resembles
Perl. The expression should be enclosed in the delimiters, a
forward slash (/), for example. Any character can be used for
delimiter as long as it's not alphanumeric or backslash (\). If
the delimiter character has to be used in the expression itself,
it needs to be escaped by backslash. Since PHP 4.0.4, you can also use
Perl-style (), {}, [], and <> matching delimiters.
The ending delimiter may be followed by various modifiers that
affect the matching.
See Pattern Modifiers.
PHP also supports regular expressions using a POSIX-extended syntax
using the POSIX-extended regex functions..
Instalace
Beginning with PHP 4.2.0 this function are enabled by default.
For older versions you have to configure and compile PHP
with --with-pcre-regex[=DIR] in order
to use these functions. You can disable the pcre functions with --without-pcre-regex.
Konfigurace běhu
Toto rozšíření nemá definováno žádné konfigurační
direktivy.
Typy prostředků
Toto rozšíření nemá definován žádný typ prostředku
(resource).
Předdefinované konstanty
Tyto konstanty jsou definovány tímto rozšířením a budou k dispozici pouze
tehdy, bylo-li rozšíření zkompilováno společně s PHP nebo dynamicky zavedeno
za běhu.
Tabulka 1. PREG constants
| constant | description |
|---|
| PREG_PATTERN_ORDER |
Orders results so that $matches[0] is an array of full pattern
matches, $matches[1] is an array of strings matched by the first
parenthesized subpattern, and so on. This flag is only used with
preg_match_all().
|
| PREG_SET_ORDER |
Orders results so that $matches[0] is an array of first set of
matches, $matches[1] is an array of second set of matches, and so
on. This flag is only used with preg_match_all().
|
| PREG_OFFSET_CAPTURE |
See the description of
PREG_SPLIT_OFFSET_CAPTURE. This flag is
available since PHP 4.3.0 .
|
| PREG_SPLIT_NO_EMPTY |
This flag tells preg_split() to only return only
non-empty pieces.
|
| PREG_SPLIT_DELIM_CAPTURE |
This flag tells preg_split() to capture
parenthesized expression in the delimiter pattern as well. This flag
is available since PHP 4.0.5 .
|
| PREG_SPLIT_OFFSET_CAPTURE |
If this flag is set, for every occuring match the appendant string
offset will also be returned. Note that this changes the return
value in an array where very element is an array consisting of the
matched string at offset 0 and it's string offset into subject at
offset 1. This flag is available since PHP 4.3.0
and is only used for preg_split().
|
Příklady
Příklad 1. Examples of valid patterns /<\/\w+>/ |(\d{3})-\d+|Sm /^(?i)php[34]/ {^\s+(\s+)?$}
|
Příklad 2. Examples of invalid patterns
/href='(.*)' - missing ending delimiter
/\w+\s*\w+/J - unknown modifier 'J'
1-\d3-\d3-\d4| - missing starting delimiter
|
recode
