(PHP 4, PHP 5)
preg_match — Perform a regular expression match
$pattern
, string $subject
[, array &$matches
[, int $flags = 0
[, int $offset = 0
]]] )
Searches subject for a match to the regular
expression given in pattern.
pattern
The pattern to search for, as a string.
subject
The input string.
matches
If matches is provided, then it is filled with
the results of search. $matches[0] will contain the
text that matched the full pattern, $matches[1]
will have the text that matched the first captured parenthesized
subpattern, and so on.
flags
flags can be the following flag:
PREG_OFFSET_CAPTURE
matches into an array where every element is an
array consisting of the matched string at offset 0
and its string offset into subject at offset
1.
offset
Normally, the search starts from the beginning of the subject string.
The optional parameter offset can be used to
specify the alternate place from which to start the search (in bytes).
Nota:
Using
offsetis not equivalent to passing substr($subject, $offset) to preg_match() in place of the subject string, becausepatterncan contain assertions such as ^, $ or (?<=x). Compare:<?php
$subject = "abcdef";
$pattern = '/^def/';
preg_match($pattern, $subject, $matches, PREG_OFFSET_CAPTURE, 3);
print_r($matches);
?>O exemplo acima irá imprimir:
Array ( )while this example
<?php
$subject = "abcdef";
$pattern = '/^def/';
preg_match($pattern, substr($subject,3), $matches, PREG_OFFSET_CAPTURE);
print_r($matches);
?>will produce
Array ( [0] => Array ( [0] => def [1] => 0 ) )
preg_match() returns 1 if the pattern
matches given subject, 0 if it does not, or FALSE
if an error occurred.
Esta função pode
retornar o booleano FALSE, mas também pode retornar um valor não-booleano que pode ser
avaliado como FALSE, como 0 ou
"". Leia a seção em Booleanos para maiores
informações. Utilize o operador ===
para testar o valor retornado por esta
função.
| Versão | Descrição |
|---|---|
| 5.3.6 |
Returns FALSE if offset is higher than
subject length.
|
| 5.2.2 | Named subpatterns now accept the syntax (?<name>) and (?'name') as well as (?P<name>). Previous versions accepted only (?P<name>). |
| 4.3.3 |
The offset parameter was added
|
| 4.3.0 |
The PREG_OFFSET_CAPTURE flag was added
|
| 4.3.0 |
The flags parameter was added
|
Exemplo #1 Find the string of text "php"
<?php
// The "i" after the pattern delimiter indicates a case-insensitive search
if (preg_match("/php/i", "PHP is the web scripting language of choice.")) {
echo "A match was found.";
} else {
echo "A match was not found.";
}
?>
Exemplo #2 Find the word "web"
<?php
/* The \b in the pattern indicates a word boundary, so only the distinct
* word "web" is matched, and not a word partial like "webbing" or "cobweb" */
if (preg_match("/\bweb\b/i", "PHP is the web scripting language of choice.")) {
echo "A match was found.";
} else {
echo "A match was not found.";
}
if (preg_match("/\bweb\b/i", "PHP is the website scripting language of choice.")) {
echo "A match was found.";
} else {
echo "A match was not found.";
}
?>
Exemplo #3 Getting the domain name out of a URL
<?php
// get host name from URL
preg_match('@^(?:http://)?([^/]+)@i',
"http://www.php.net/index.html", $matches);
$host = $matches[1];
// get last two segments of host name
preg_match('/[^.]+\.[^.]+$/', $host, $matches);
echo "domain name is: {$matches[0]}\n";
?>
O exemplo acima irá imprimir:
domain name is: php.net
Exemplo #4 Using named subpattern
<?php
$str = 'foobar: 2008';
preg_match('/(?P<name>\w+): (?P<digit>\d+)/', $str, $matches);
/* This also works in PHP 5.2.2 (PCRE 7.0) and later, however
* the above form is recommended for backwards compatibility */
// preg_match('/(?<name>\w+): (?<digit>\d+)/', $str, $matches);
print_r($matches);
?>
O exemplo acima irá imprimir:
Array
(
[0] => foobar: 2008
[name] => foobar
[1] => foobar
[digit] => 2008
[2] => 2008
)