preg_match

Perform a regular expression match

 **preg_match** string $pattern string $subject array $matches int $flags int $offset

Searches for a match to the regular expression given in . subject``pattern

patternThe pattern to search for, as a string.

subjectThe input string.

matches If is provided, then it is filled with the results of search. will contain the text that matched the full pattern, will have the text that matched the first captured parenthesized subpattern, and so on. matches``$matches[0]``$matches[1]

flags can be a combination of the following flags:

  `flags``PREG_OFFSET_CAPTURE`
       If this flag is passed, for every occurring match the appendant string
       offset (in bytes) will also be returned. Note that this changes the value of
        into an array where every element is an
       array consisting of the matched string at offset 
       and its string offset into  at offset
       .
       
      `matches``0``subject``1````php


```php
Array
(
    [0] => Array
        (
            [0] => foobarbaz
            [1] => 0
        )

    [1] => Array
        (
            [0] => foo
            [1] => 0
        )

    [2] => Array
        (
            [0] => bar
            [1] => 3
        )

    [3] => Array
        (
            [0] => baz
            [1] => 6
        )

)

PREG_UNMATCHED_AS_NULL If this flag is passed, unmatched subpatterns are reported as null; otherwise they are reported as an empty .

      `string````php


```php
array(4) {
  [0]=>
  string(2) "ac"
  [1]=>
  string(1) "a"
  [2]=>
  string(0) ""
  [3]=>
  string(1) "c"
}
array(4) {
  [0]=>
  string(2) "ac"
  [1]=>
  string(1) "a"
  [2]=>
  NULL
  [3]=>
  string(1) "c"
}

offset Normally, the search starts from the beginning of the subject string. The optional parameter can be used to specify the alternate place from which to start the search (in bytes). offset

Opmerking: > Using is not equivalent to passing to in place of the subject string, because can contain assertions such as , or . Compare:

   `offset``substr($subject, $offset)``preg_match``pattern`*^**$**(?&lt;=x)*```php


```php
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
        )

)

      Alternatively, to avoid using , use the
       assertion rather than the  anchor, or
      the  modifier instead, both of which work with
      the  parameter.
     `substr``\G``^``A``offset`

returns 1 if the

matches given , 0 if it does not,return.falseforfailure. preg_match``pattern``subject

Voorbeeld: 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.";
}
?>

Voorbeeld: 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.";
}

echo "\n";

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.";
}
?>

Voorbeeld: 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";
?>

domain name is: php.net

Voorbeeld: Using named subpattern

<?php

$str = 'foobar: 2008';

preg_match('/(?P<name>\w+): (?P<digit>\d+)/', $str, $matches);

/* Alternative */
// preg_match('/(?<name>\w+): (?<digit>\d+)/', $str, $matches);

print_r($matches);

?>

Array
(
    [0] => foobar: 2008
    [name] => foobar
    [1] => foobar
    [digit] => 2008
    [2] => 2008
)

Tip: > Do not use if you only want to check if one string is contained in another string. Use instead as it will be faster. preg_match``strpos

PCRE Patternspreg_quote``preg_match_all``preg_replace``preg_split``preg_last_error``preg_last_error_msg

Vorige ← preg_match_all Volgende preg_quote →

preg_match

preg_match

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