What is preg_match_all in php?

The above example will output:

example: , 
this is a test
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].

preg_match_all(
    '/(?J)(?foo)|(?bar)/',
    'foo bar',
    $matches,
    PREG_PATTERN_ORDER
);
print_r($matches['match']);
?>

The above example will output:

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

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_match_all("|<[^>]+>(.*)]+>|U",
    "example: this is a test",
    $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:

example: , example:
this is a test
, this is a test

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 offset 0 and its string offset into subject at offset 1.

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
                )

        )

)

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.

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 on failure.

Errors/Exceptions

If the regex pattern passed does not compile to a valid regex, an E_WARNING is emitted.

Changelog

Examples

Example #1 Getting all phone numbers out of some text.

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)

// 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 = "bold textclick me";preg_match_all("/(<([\w]+)[^>]*>)(.*?)(<\/\\2>)/", $html, $matches, PREG_SET_ORDER);

foreach (

The above example will output:

matched: bold text
part 1: 
part 2: b
part 3: bold text
part 4: 

matched: click me
part 1: 
part 2: a
part 3: click me
part 4: 

Example #3 Using named subpattern

$str

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

buuh ¶

11 years ago

if you want to extract all {token}s from a string:

$pattern = "/{[^}]*}/";
$subject = "{token1} foo {token2} bar";
preg_match_all($pattern, $subject, $matches);
print_r($matches);
?>

output:

Array
(
    [0] => Array
        (
            [0] => {token1}
            [1] => {token2}
        )

)

Daniel Klein ¶

7 years ago

The code that john at mccarthy dot net posted is not necessary. If you want your results grouped by individual match simply use:

preg_match_all($pattern, $string, $matches, PREG_SET_ORDER);
?>

E.g.

preg_match_all('/([GH])([12])([!?])/', 'G1? H2!', $matches); // Default PREG_PATTERN_ORDER
// $matches = array(0 => array(0 => 'G1?', 1 => 'H2!'),
//                  1 => array(0 => 'G', 1 => 'H'),
//                  2 => array(0 => '1', 1 => '2'),
//                  3 => array(0 => '?', 1 => '!'))

preg_match_all('/([GH])([12])([!?])/', 'G1? H2!', $matches, PREG_SET_ORDER);
// $matches = array(0 => array(0 => 'G1?', 1 => 'G', 2 => '1', 3 => '?'),
//                  1 => array(0 => 'H2!', 1 => 'H', 2 => '2', 3 => '!'))
?>

mnc at u dot nu ¶

16 years ago

PREG_OFFSET_CAPTURE always seems to provide byte offsets, rather than character position offsets, even when you are using the unicode /u modifier.

phpnet at sinful-music dot com ¶

16 years ago

Here's some fleecy code to 1. validate RCF2822 conformity of address lists and 2. to extract the address specification (the part commonly known as 'email'). I wouldn't suggest using it for input form email checking, but it might be just what you want for other email applications. I know it can be optimized further, but that part I'll leave up to you nutcrackers. The total length of the resulting Regex is about 30000 bytes. That because it accepts comments. You can remove that by setting $cfws to $fws and it shrinks to about 6000 bytes. Conformity checking is absolutely and strictly referring to RFC2822. Have fun and email me if you have any enhancements!

function mime_extract_rfc2822_address($string)
{
        //rfc2822 token setup
        $crlf           = "(?:\r\n)";
        $wsp            = "[\t ]";
        $text           = "[\\x01-\\x09\\x0B\\x0C\\x0E-\\x7F]";
        $quoted_pair    = "(?:\\\\$text)";
        $fws            = "(?:(?:$wsp*$crlf)?$wsp+)";
        $ctext          = "[\\x01-\\x08\\x0B\\x0C\\x0E-\\x1F" .
                          "!-'*-[\\]-\\x7F]";
        $comment        = "(\\((?:$fws?(?:$ctext|$quoted_pair|(?1)))*" .
                          "$fws?\\))";
        $cfws           = "(?:(?:$fws?$comment)*(?:(?:$fws?$comment)|$fws))";
        //$cfws           = $fws; //an alternative to comments
        $atext          = "[!#-'*+\\-\\/0-9=?A-Z\\^-~]";
        $atom           = "(?:$cfws?$atext+$cfws?)";
        $dot_atom_text  = "(?:$atext+(?:\\.$atext+)*)";
        $dot_atom       = "(?:$cfws?$dot_atom_text$cfws?)";
        $qtext          = "[\\x01-\\x08\\x0B\\x0C\\x0E-\\x1F!#-[\\]-\\x7F]";
        $qcontent       = "(?:$qtext|$quoted_pair)";
        $quoted_string  = "(?:$cfws?\"(?:$fws?$qcontent)*$fws?\"$cfws?)";
        $dtext          = "[\\x01-\\x08\\x0B\\x0C\\x0E-\\x1F!-Z\\^-\\x7F]";
        $dcontent       = "(?:$dtext|$quoted_pair)";
        $domain_literal = "(?:$cfws?\\[(?:$fws?$dcontent)*$fws?]$cfws?)";
        $domain         = "(?:$dot_atom|$domain_literal)";
        $local_part     = "(?:$dot_atom|$quoted_string)";
        $addr_spec      = "($local_part@$domain)";
        $display_name   = "(?:(?:$atom|$quoted_string)+)";
        $angle_addr     = "(?:$cfws?<$addr_spec>$cfws?)";
        $name_addr      = "(?:$display_name?$angle_addr)";
        $mailbox        = "(?:$name_addr|$addr_spec)";
        $mailbox_list   = "(?:(?:(?:(?<=:)|,)$mailbox)+)";
        $group          = "(?:$display_name:(?:$mailbox_list|$cfws)?;$cfws?)";
        $address        = "(?:$mailbox|$group)";
        $address_list   = "(?:(?:^|,)$address)+";//output length of string (just so you see how f**king long it is)
        echo(strlen($address_list) . " ");//apply expression
        preg_match_all("/^$address_list$/", $string, $array, PREG_SET_ORDER);

        return

chuckie ¶

15 years ago

This is a function to convert byte offsets into (UTF-8) character offsets (this is reagardless of whether you use /u modifier:

function mb_preg_match_all($ps_pattern, $ps_subject, &$pa_matches, $pn_flags = PREG_PATTERN_ORDER, $pn_offset = 0, $ps_encoding = NULL) {
  // WARNING! - All this function does is to correct offsets, nothing else:
  //
  if (is_null($ps_encoding))
    $ps_encoding = mb_internal_encoding();$pn_offset = strlen(mb_substr($ps_subject, 0, $pn_offset, $ps_encoding));
  $ret = preg_match_all($ps_pattern, $ps_subject, $pa_matches, $pn_flags, $pn_offset);

  if (

fab ¶

9 years ago

Here is a function that replaces all occurrences of a number in a string by the number--

function decremente_chaine($chaine)
    {
        //récupérer toutes les occurrences de nombres et leurs indices
        preg_match_all("/[0-9]+/",$chaine,$out,PREG_OFFSET_CAPTURE);
            //parcourir les occurrences
            for($i=0;$i<sizeof($out[0]);$i++)
            {
                $longueurnombre = strlen((string)$out[0][$i][0]);
                $taillechaine = strlen($chaine);
                // découper la chaine en 3 morceaux
                $debut = substr($chaine,0,$out[0][$i][1]);
                $milieu = ($out[0][$i][0])-1;
                $fin = substr($chaine,$out[0][$i][1]+$longueurnombre,$taillechaine);
                 // si c'est 10,100,1000 etc. on décale tout de 1 car le résultat comporte un chiffre de moins
                 if(preg_match('#[1][0]+$#', $out[0][$i][0]))
                 {
                    for($j = $i+1;$j<sizeof($out[0]);$j++)
                    {
                        $out[0][$j][1] = $out[0][$j][1] -1;
                    }
                 }
                $chaine = $debut.$milieu.$fin;
            }
        return $chaine;
    }
?>

sledge NOSPAM ¶

14 years ago

Perhaps you want to find the positions of all anchor tags.  This will return a two dimensional array of which the starting and ending positions will be returned.

function getTagPositions($strBody)
{
    define(DEBUG, false);
    define(DEBUG_FILE_PREFIX, "/tmp/findlinks_");preg_match_all("/<[^>]+>(.*)<\/[^>]+>/U", $strBody, $strTag, PREG_PATTERN_ORDER);
    $intOffset = 0;
    $intIndex = 0;
    $intTagPositions = array();

    foreach(

bruha ¶

14 years ago

To count str_length in UTF-8 string i use

$count = preg_match_all("/[[:print:]\pL]/u", $str, $pockets);

where
[:print:] - printing characters, including space
\pL - UTF-8 Letter
/u - UTF-8 string
other unicode character properties on http://www.pcre.org/pcre.txt

Better use preg_replace to convert text in a clickable link with tag

$html = preg_replace('"\b(http://\S+)"', '$1', $text);

royaltm75 at gmail dot com ¶

12 years ago

I have received complains, that my html2a() code (see below) doesn't work in some cases.
It is however not the problem with algorithm or procedure, but with PCRE recursive stack limits.

If you use recursive PCRE (?R) you should remember to increase those two ini settings:

ini_set('pcre.backtrack_limit', 10000000);
ini_set('pcre.recursion_limit', 10000000);

But be warned: (from php.ini)

;Please note that if you set this value to a high number you may consume all
;the available process stack and eventually crash PHP (due to reaching the
;stack size limit imposed by the Operating System).

I have written this example mainly to demonstrate the power of PCRE LANGUAGE, not the power of it's implementation  :)

But if you like it, use it, of course on your own risk.

elyknosrac at gmail dot com ¶

13 years ago

Using preg_match_all I made a pretty handy function.

function reg_smart_replace($pattern, $replacement, $subject, $replacementChar = "$$$", $limit = -1)
{
    if (! $pattern || ! $subject || ! $replacement ) { return false; } $replacementChar = preg_quote($replacementChar); preg_match_all ( $pattern, $subject, $matches);

        if (

MonkeyMan ¶

13 years ago

Here is a way to match everything on the page, performing an action for each match as you go. I had used this idiom in other languages, where its use is customary, but in PHP it seems to be not quite as common.

function custom_preg_match_all($pattern, $subject)
{
    $offset = 0;
    $match_count = 0;
    while(preg_match($pattern, $subject, $matches, PREG_OFFSET_CAPTURE, $offset))
    {
        // Increment counter
        $match_count++;// Get byte offset and byte length (assuming single byte encoded)
        $match_start = $matches[0][1];
        $match_length = strlen(matches[0][0]);// (Optional) Transform $matches to the format it is usually set as (without PREG_OFFSET_CAPTURE set)
        foreach($matches as $k => $match) $newmatches[$k] = $match[0];
        $matches = $new_matches;// Your code here
        echo "Match number $match_count, at byte offset $match_start, $match_length bytes long: ".$matches[0]."\r\n";// Update offset to the end of the match
        $offset = $match_start + $match_length;
    }

    return

dolbegraeb ¶

14 years ago

please note, that the function of "mail at SPAMBUSTER at milianw dot de" can result in invalid xhtml in some cases. think i used it in the right way but my result is sth like this:

correct me if i'm wrong.
i'll see when there's time to fix that. -.-

matt at lvl99 dot com ¶

6 years ago

I had been crafting and testing some regexp patterns online using the tools Regex101 and a `preg_match_all()` tester and found that the regexp patterns I wrote worked fine on them, just not in my code.

My problem was not double-escaping backslash characters:

// Input test
$input = "\"something\",\"something here\",\"some\nnew\nlines\",\"this is the end\"";// Work with online regexp testers, doesn't work in PHP
preg_match_all( "/(?:,|^)(?, $input, $matches );/*
Outputs: NULL
*/

// Works with online regexp testers, does work in PHP

phektus at gmail dot com ¶

15 years ago

If you'd like to include DOUBLE QUOTES on a regular expression for use with preg_match_all, try ESCAPING THRICE, as in: \\\"

For example, the pattern:
'/

Should be able to match:


I'm not really sure why this is so, but I tried just the double quote and one or even two escape characters and it won't work. In my frustration I added another one and then it's cool.

mr davin ¶

15 years ago

// Returns an array of strings where the start and end are found
    function findinside($start, $end, $string) {
        preg_match_all('/' . preg_quote($start, '/') . '([^\.)]+)'. preg_quote($end, '/').'/i', $string, $m);
        return $m[1];
    }$start = "mary has";
    $end = "lambs.";
    $string = "mary has 6 lambs. phil has 13 lambs. mary stole phil's lambs. now mary has all the lambs.";$out = findinside($start, $end, $string);print_r ($out);/* Results in
(
    [0] =>  6
    [1] =>  all the
)
*/
?>

vojjov dot artem at ya dot ru ¶

7 years ago

// Here is function that allows you to preg_match_all array of patters

function getMatches($pattern, $subject) {
    $matches = array();

    if (is_array($pattern)) {
        foreach ($pattern as $p) {
            $m = getMatches($p, $subject);

            foreach ($m as $key => $match) {
                if (isset($matches[$key])) {
                    $matches[$key] = array_merge($matches[$key], $m[$key]);   
                } else {
                    $matches[$key] = $m[$key];
                }
            }
        }
    } else {
        preg_match_all($pattern, $subject, $matches);
    }

    return $matches;
}

$patterns = array(
    '/(.*?)<\/span>/',
    '/(.*?)<\/a>/'
);

$html = 'some text';
$html .= 'some text in another span';
$html .= 'here is the link';
$html .= '

$matches = getMatches($patterns, $html);

print_r($matches); // result is below

/*
Array
(
    [0] => Array
        (
            [0] => some text
            [1] => some text in another span
            [2] => here is one more span
            [3] => here is the link
        )

    [1] => Array
        (
            [0] => some text
            [1] => some text in another span
            [2] => here is one more span
            [3] => here is the link
        )

)
*/

satyavvd at ymail dot com ¶

10 years ago

Extract fields out of csv string : ( since before php5.3 you can't use str_getcsv function )
Here is the regex :

$csvData

royaltm75 at NOSPAM dot gmail dot com ¶

13 years ago

The power of pregs is limited only by your *imagination* :)
I wrote this html2a() function using preg recursive match (?R) which provides quite safe and bulletproof html/xml extraction:
function html2a ( $html ) {
  if ( !preg_match_all( '
@
\<\s*?(\w+)((?:\b(?:\'[^\']*\'|"[^"]*"|[^\>])*)?)\>
((?:(?>[^\<]*)|(?R))*)
\<\/\s*?\\1(?:\b[^\>]*)?\>
|\<\s*(\w+)(\b(?:\'[^\']*\'|"[^"]*"|[^\>])*)?\/?\>
@uxis', $html = trim($html), $m, PREG_OFFSET_CAPTURE | PREG_SET_ORDER) )
    return $html;
  $i = 0;
  $ret = array();
  foreach ($m as $set) {
    if ( strlen( $val = trim( substr($html, $i, $set[0][1] - $i) ) ) )
      $ret[] = $val;
    $val = $set[1][1] < 0
      ? array( 'tag' => strtolower($set[4][0]) )
      : array( 'tag' => strtolower($set[1][0]), 'val' => html2a($set[3][0]) );
    if ( preg_match_all( '
/(\w+)\s*(?:=\s*(?:"([^"]*)"|\'([^\']*)\'|(\w+)))?/usix
', isset($set[5]) && $set[2][1] < 0
  ? $set[5][0]
  : $set[2][0]
  ,$attrs, PREG_SET_ORDER ) ) {
      foreach ($attrs as $a) {
        $val['attr'][$a[1]]=$a[count($a)-1];
      }
    }
    $ret[] = $val;
    $i = $set[0][1]+strlen( $set[0][0] );
  }
  $l = strlen($html);
  if ( $i < $l )
    if ( strlen( $val = trim( substr( $html, $i, $l - $i ) ) ) )
      $ret[] = $val;
  return $ret;
}
?>

Now let's try it with this example: (there are some really nasty xhtml compliant bugs, but ... we shouldn't worry)

$html = <<some leftover text...
     < DIV class=noCompliant style = "text-align:left;" >
... and some other ...
< dIv > < empty> 
 

This is yet another text
     that wasn't compliant too...
    

function

DarkSide ¶

8 years ago

This is very useful to combine matches:
$a = array_combine($matches[1], $matches[2]);

avengis at gmail dot com ¶

12 years ago

The next function works with almost any complex xml/xhtml string

/**
* Find and close unclosed xml tags
**/
function close_tags($text) {
    $patt_open    = "%((?\s]+(?=>|[\s]+[^>]*[^/]>)(?!/>))%";
    $patt_close    = "%((?<=]+)(?=>))%";
    if (preg_match_all($patt_open,$text,$matches))
    {
        $m_open = $matches[1];
        if(!empty($m_open))
        {
            preg_match_all($patt_close,$text,$matches2);
            $m_close = $matches2[1];
            if (count($m_open) > count($m_close))
            {
                $m_open = array_reverse($m_open);
                foreach ($m_close as $tag) $c_tags[$tag]++;
                foreach ($m_open as $k => $tag)    if ($c_tags[$tag]--<=0) $text.='.$tag.'>';
            }
        }
    }
    return $text;
}
?>

What is the use of preg match?

What is PHP regex?

What is Preg_replace function in PHP?

What does preg match return?