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preg_match_all
Perform a global regular expression match
Description
int preg_match_all
( string $pattern
, string $subject
[, array &$matches
[, int $flags = PREG_PATTERN_ORDER
[, int $offset = 0
]]] )
After the first match is found, the subsequent searches are continued
on from end of the last match.
Parameters
-
pattern
-
The pattern to search for, as a string.
-
subject
-
The input string.
-
matches
-
Array of all matches in multi-dimensional array ordered according to
flags.
-
flags
-
Can be a combination of the following flags (note that it doesn't make
sense to use PREG_PATTERN_ORDER together with
PREG_SET_ORDER):
-
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.
-
PREG_SET_ORDER
-
Orders results so that $matches[0] is an array of first set
of matches, $matches[1] is an array of second set of matches,
and so on.
-
PREG_OFFSET_CAPTURE
-
If this flag is passed, for every occurring match the appendant string
offset will also be returned. Note that this changes the value of
matches into an array where every element is an
array consisting of the matched string at offset 0
and its string offset into subject at offset
1.
If no order flag is given, PREG_PATTERN_ORDER is
assumed.
-
offset
-
Normally, the search starts from the beginning of the subject string.
The optional parameter offset can be used to
specify the alternate place from which to start the search (in bytes).
Note:
Using offset is not equivalent to passing
substr($subject, $offset) to
preg_match_all in place of the subject string,
because pattern can contain assertions such as
^, $ or
(?<=x). See preg_match
for examples.
Return Values
Returns the number of full pattern matches (which might be zero),
or FALSE if an error occurred.
Examples
Example #1 Getting all phone numbers out of some text.
<?php
preg_match_all("/\(? (\d{3})? \)? (?(1) [\-\s] ) \d{3}-\d{4}/x",
"Call 555-1212 or 1-800-555-1212", $phones);
?>
Example #2 Find matching HTML tags (greedy)
<?php
// The \\2 is an example of backreferencing. This tells pcre that
// it must match the second set of parentheses in the regular expression
// itself, which would be the ([\w]+) in this case. The extra backslash is
// required because the string is in double quotes.
$html = "<b>bold text</b><a href=howdy.html>click me</a>";
preg_match_all("/(<([\w]+)[^>]*>)(.*?)(<\/\\2>)/", $html, $matches, PREG_SET_ORDER);
foreach ($matches as $val) {
echo "matched: " . $val[0] . "\n";
echo "part 1: " . $val[1] . "\n";
echo "part 2: " . $val[2] . "\n";
echo "part 3: " . $val[3] . "\n";
echo "part 4: " . $val[4] . "\n\n";
}
?>
The above example will output:
matched: <b>bold text</b>
part 1: <b>
part 2: b
part 3: bold text
part 4: </b>
matched: <a href=howdy.html>click me</a>
part 1: <a href=howdy.html>
part 2: a
part 3: click me
part 4: </a>
Example #3 Using named subpattern
<?php
$str = <<<FOO
a: 1
b: 2
c: 3
FOO;
preg_match_all('/(?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_all('/(?<name>\w+): (?<digit>\d+)/', $str, $matches);
print_r($matches);
?>
The above example will output:
Array
(
[0] => Array
(
[0] => a: 1
[1] => b: 2
[2] => c: 3
)
[name] => Array
(
[0] => a
[1] => b
[2] => c
)
[1] => Array
(
[0] => a
[1] => b
[2] => c
)
[digit] => Array
(
[0] => 1
[1] => 2
[2] => 3
)
[2] => Array
(
[0] => 1
[1] => 2
[2] => 3
)
)
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