preg_match_all
(PHP 4, PHP 5, PHP 7, PHP 8)
preg_match_all — Perform a global regular expression match
Description
string
$pattern
,string
$subject
,array
&$matches
= null
,int
$flags
= 0,int
$offset
= 0): int|false
Searches subject
for all matches to the regular
expression given in pattern
and puts them in
matches
in the order specified by
flags
.
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 withPREG_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.
<?php
preg_match_all("|<[^>]+>(.*)</[^>]+>|U",
"<b>example: </b><div align=left>this is a test</div>",
$out, PREG_PATTERN_ORDER);
echo $out[0][0] . ", " . $out[0][1] . "\n";
echo $out[1][0] . ", " . $out[1][1] . "\n";
?>The above example will output:
<b>example: </b>, <div align=left>this is a test</div> example: , this is a test
So, $out[0] contains array of strings that matched full pattern, and $out[1] contains array of strings enclosed by tags.
If the pattern contains named subpatterns, $matches additionally contains entries for keys with the subpattern name.
If the pattern contains duplicate named subpatterns, only the rightmost subpattern is stored in $matches[NAME].
<?php
preg_match_all(
'/(?J)(?<match>foo)|(?<match>bar)/',
'foo bar',
$matches,
PREG_PATTERN_ORDER
);
print_r($matches['match']);
?>The above example will output:
Array ( [0] => [1] => bar )
-
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.
<?php
preg_match_all("|<[^>]+>(.*)</[^>]+>|U",
"<b>example: </b><div align=\"left\">this is a test</div>",
$out, PREG_SET_ORDER);
echo $out[0][0] . ", " . $out[0][1] . "\n";
echo $out[1][0] . ", " . $out[1][1] . "\n";
?>The above example will output:
<b>example: </b>, example: <div align="left">this is a test</div>, this is a test
-
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
matches
into an array of arrays where every element is an array consisting of the matched string at offset0
and its string offset intosubject
at offset1
.<?php
preg_match_all('/(foo)(bar)(baz)/', 'foobarbaz', $matches, PREG_OFFSET_CAPTURE);
print_r($matches);
?>The above example will output:
Array ( [0] => Array ( [0] => Array ( [0] => foobarbaz [1] => 0 ) ) [1] => Array ( [0] => Array ( [0] => foo [1] => 0 ) ) [2] => Array ( [0] => Array ( [0] => bar [1] => 3 ) ) [3] => Array ( [0] => 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.
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 passingsubstr($subject, $offset)
to preg_match_all() in place of the subject string, becausepattern
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
on failure.
Errors/Exceptions
If the regex pattern passed does not compile to a valid regex, an E_WARNING
is emitted.
Changelog
Version | Description |
---|---|
7.2.0 |
The PREG_UNMATCHED_AS_NULL is now supported for the
$flags parameter.
|
Examples
Example #1 Getting all phone numbers out of some text.
<?php
preg_match_all("/\(? (\d)? \)? (?(1) [\-\s] ) \d-\d/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);
/* Alternative */
// 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 ) )
See Also
- PCRE Patterns
- preg_quote() - Quote regular expression characters
- preg_match() - Perform a regular expression match
- preg_replace() - Perform a regular expression search and replace
- preg_split() - Split string by a regular expression
- preg_last_error() - Returns the error code of the last PCRE regex execution