PHP 7.0.6 Released

    preg_match

    (PHP 4, PHP 5, PHP 7)

    preg_match — Perform a regular expression match

    Description

    int preg_match ( string $pattern , string $subject [, array &$matches [, int $flags = 0 [, int $offset = 0 ]]] )

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

    Parameters

    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
    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.

    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() in place of the subject string, because pattern can contain assertions such as ^, $ or (?<=x). Compare:

    <?php
    $subject     = "abcdef";
    $pattern = '/^def/';
    preg_match($pattern, $subject, $matches, PREG_OFFSET_CAPTURE, 3);
    print_r($matches);
    ?>

    The above example will output:

    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
        )

)

    Return Values

    preg_match() returns 1 if the pattern matches given subject, 0 if it does not, or FALSE if an error occurred.

    Warning

    This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.

    Changelog

    Version Description
    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>).

    Examples

    Example #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.";
    }
    ?>

    Example #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.";
    }
    ?>

    Example #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";
    ?>

    The above example will output:

    domain name is: php.net

    Example #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);

    ?>

    The above example will output:

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

    Notes

    Tip

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

    See Also

    User Contributed Notes

    force at md-t dot org
    4 years ago
    Simple regex

    Regex quick reference
    [abc]     A single character: a, b or c
    [^abc]     Any single character but a, b, or c
    [a-z]     Any single character in the range a-z
    [a-zA-Z]     Any single character in the range a-z or A-Z
    ^     Start of line
    $     End of line
    \A     Start of string
    \z     End of string
    .     Any single character
    \s     Any whitespace character
    \S     Any non-whitespace character
    \d     Any digit
    \D     Any non-digit
    \w     Any word character (letter, number, underscore)
    \W     Any non-word character
    \b     Any word boundary character
    (...)     Capture everything enclosed
    (a|b)     a or b
    a?     Zero or one of a
    a*     Zero or more of a
    a+     One or more of a
    a{3}     Exactly 3 of a
    a{3,}     3 or more of a
    a{3,6}     Between 3 and 6 of a

    options: i case insensitive m make dot match newlines x ignore whitespace in regex o perform #{...} substitutions only once
    MrBull
    5 years ago
    Sometimes its useful to negate a string. The first method which comes to mind to do this is: [^(string)] but this of course won't work. There is a solution, but it is not very well known. This is the simple piece of code on how a negation of a string is done:

    (?:(?!string).)

    ?: makes a subpattern (see http://www.php.net/manual/en/regexp.reference.subpatterns.php) and ?! is a negative look ahead. You put the negative look ahead in front of the dot because you want the regex engine to first check if there is an occurrence of the string you are negating. Only if it is not there, you want to match an arbitrary character.

    Hope this helps some ppl.
    ian_channing at hotmail dot com
    5 years ago
    When trying to check a file path that could be windows or unix it took me quite a few tries to get the escape characters right.

    The Unix directory separator must be escaped once and the windows directory separator must be escaped twice.

    This will match path/to/file and path\to\file.exe

    preg_match('/^[a-z0-9_.\/\\\]*$/i', $file_string);
    mohammad40g at gmail dot com
    4 years ago
    This sample is for checking persian character:

    <?php
       preg_match    ("/[\x{0600}-\x{06FF}\x]{1,32}/u", 'محمد');
    ?>
    jonathan dot lydall at gmail dot removethispart dot com
    7 years ago
    Because making a truly correct email validation function is harder than one may think, consider using this one which comes with PHP through the filter_var function (http://www.php.net/manual/en/function.filter-var.php):

    <?php
    $email     = "someone@domain .local";

    if(!    filter_var($email, FILTER_VALIDATE_EMAIL)) {
        echo     "E-mail is not valid";
    } else {
        echo     "E-mail is valid";
    }
    ?>
    arash dot hemmat at gmail dot com
    5 years ago
    For those who search for a unicode regular expression example using preg_match here it is:

    Check for Persian digits
    preg_match( "/[^\x{06F0}-\x{06F9}\x]+/u" , '۱۲۳۴۵۶۷۸۹۰' );
    wjaspers4[at]gmail[dot]com
    7 years ago
    I found this rather useful for testing mutliple strings when developing a regex pattern.
    <?php
    /**
    * Runs preg_match on an array of strings and returns a result set.
    * @author wjaspers4[at]gmail[dot]com
    * @param String $expr The expression to match against
    * @param Array $batch The array of strings to test.
    * @return Array
    */
    function preg_match_batch( $expr, $batch=array() )
    {
    // create a placeholder for our results
            $returnMe = array();

    // for every string in our batch ...
            foreach( $batch as $str )
        {
    // test it, and dump our findings into $found
                preg_match($expr, $str, $found);

    // append our findings to the placeholder
                $returnMe[$str] = $found;
        }

        return     $returnMe;
    }
    ?>
    cebelab at gmail dot com
    6 years ago
    I noticed that in order to deal with UTF-8 texts, without having to recompile php with the PCRE UTF-8 flag enabled, you can just add the following sequence at the start of your pattern: (*UTF8)

    for instance : '#(*UTF8)[[:alnum:]]#' will return TRUE for 'é' where '#[[:alnum:]]#' will return FALSE

    found this very very useful tip after hours of research over the web directly in pcre website right here : http://www.pcre.org/pcre.txt
    there are many further informations about UTF-8 support in the lib

    hop that will help!

    --
    cedric
    Yousef Ismaeil Cliprz
    3 years ago
    Some times a Hacker use a php file or shell as a image to hack your website. so if you try to use move_uploaded_file() function as in example to allow for users to upload files, you must check if this file contains a bad codes or not so we use this function. preg match

    in this function we use

    unlink() - http://php.net/unlink

    after you upload file check a file with below function.

    <?php

    /**
    * A simple function to check file from bad codes.
    *
    * @param (string) $file - file path.
    * @author Yousef Ismaeil - Cliprz[at]gmail[dot]com.
    */
    function is_clean_file ($file)
    {
        if (    file_exists($file))
        {
                $contents = file_get_contents($file);
        }
        else
        {
            exit(    $file." Not exists.");
        }

        if (    preg_match('/(base64_|eval|system|shell_|exec|php_)/i',$contents))
        {
            return     true;
        }
        else if (    preg_match("#&\#x([0-9a-f]+);#i", $contents))
        {
            return     true;
        }
        elseif (    preg_match('#&\#([0-9]+);#i', $contents))
        {
            return     true;
        }
        elseif (    preg_match("#([a-z]*)=([\`\'\"]*)script:#iU", $contents))
        {
            return     true;
        }
        elseif (    preg_match("#([a-z]*)=([\`\'\"]*)javascript:#iU", $contents))
        {
            return     true;
        }
        elseif (    preg_match("#([a-z]*)=([\'\"]*)vbscript:#iU", $contents))
        {
            return     true;
        }
        elseif (    preg_match("#(<[^>]+)style=([\`\'\"]*).*expression\([^>]*>#iU", $contents))
        {
            return     true;
        }
        elseif (    preg_match("#(<[^>]+)style=([\`\'\"]*).*behaviour\([^>]*>#iU", $contents))
        {
            return     true;
        }
        elseif (    preg_match("#</*(applet|link|style|script|iframe|frame|frameset|html|body|title|div|p|form)[^>]*>#i", $contents))
        {
            return     true;
        }
        else
        {
            return     false;
        }
    }
    ?>

    Use

    <?php
    // If image contains a bad codes
    $image   = "simpleimage.png";

    if (    is_clean_file($image))
    {
        echo     "Bad codes this is not image";
            unlink($image);
    }
    else
    {
        echo     "This is a real image.";
    }
    ?>
    Jonny 5
    4 years ago
    Workaround for getting the offset in UTF-8
    (in some cases mb_strpos might be an option as well)

    <?php
    if(preg_match($pattern,$haystack,$out,PREG_OFFSET_CAPTURE)) {
            $offset = strlen(utf8_decode(substr($haystack,0,$out[0][1])));
    }
    ?>
    corey [works at] effim [delete] .com
    7 years ago
    I see a lot of people trying to put together phone regex's and struggling (hey, no worries...they're complicated). Here's one that we use that's pretty nifty. It's not perfect, but it should work for most non-idealists.

    *** Note: Only matches U.S. phone numbers. ***

    <?php

    // all on one line...
    $regex = '/^(?:1(?:[. -])?)?(?:\((?=\d{3}\)))?([2-9]\d{2})(?:(?<=\(\d{3})\))? ?(?:(?<=\d{3})[.-])?([2-9]\d{2})[. -]?(\d{4})(?: (?i:ext)\.? ?(\d{1,5}))?$/';

    // or broken up
    $regex = '/^(?:1(?:[. -])?)?(?:\((?=\d{3}\)))?([2-9]\d{2})'
                .'(?:(?<=\(\d{3})\))? ?(?:(?<=\d{3})[.-])?([2-9]\d{2})'
                .'[. -]?(\d{4})(?: (?i:ext)\.? ?(\d{1,5}))?$/';

    ?>

    If you're wondering why all the non-capturing subpatterns (which look like this "(?:", it's so that we can do this:

    <?php

    $formatted     = preg_replace($regex, '($1) $2-$3 ext. $4', $phoneNumber);

    // or, provided you use the $matches argument in preg_match

    $formatted = "($matches[1]) $matches[2]-$matches[3]";
    if (    $matches[4]) $formatted .= " $matches[4]";

    ?>

    *** Results: ***
    520-555-5542 :: MATCH
    520.555.5542 :: MATCH
    5205555542 :: MATCH
    520 555 5542 :: MATCH
    520) 555-5542 :: FAIL
    (520 555-5542 :: FAIL
    (520)555-5542 :: MATCH
    (520) 555-5542 :: MATCH
    (520) 555 5542 :: MATCH
    520-555.5542 :: MATCH
    520 555-0555 :: MATCH
    (520)5555542 :: MATCH
    520.555-4523 :: MATCH
    19991114444 :: FAIL
    19995554444 :: MATCH
    514 555 1231 :: MATCH
    1 555 555 5555 :: MATCH
    1.555.555.5555 :: MATCH
    1-555-555-5555 :: MATCH
    520-555-5542 ext.123 :: MATCH
    520.555.5542 EXT 123 :: MATCH
    5205555542 Ext. 7712 :: MATCH
    520 555 5542 ext 5 :: MATCH
    520) 555-5542 :: FAIL
    (520 555-5542 :: FAIL
    (520)555-5542 ext .4 :: FAIL
    (512) 555-1234 ext. 123 :: MATCH
    1(555)555-5555 :: MATCH
    daevid at daevid dot com
    7 years ago
    I just learned about named groups from a Python friend today and was curious if PHP supported them, guess what -- it does!!!

    http://www.regular-expressions.info/named.html

    <?php
       preg_match    ("/(?P<foo>abc)(.*)(?P<bar>xyz)/",
                               'abcdefghijklmnopqrstuvwxyz',
                               $matches);
           print_r($matches);
    ?>

    will produce:

    Array
    (
        [0] => abcdefghijklmnopqrstuvwxyz
        [foo] => abc
        [1] => abc
        [2] => defghijklmnopqrstuvw
        [bar] => xyz
        [3] => xyz
    )

    Note that you actually get the named group as well as the numerical key
    value too, so if you do use them, and you're counting array elements, be
    aware that your array might be bigger than you initially expect it to be.
    luc _ santeramo at t yahoo dot com
    6 years ago
    If you want to validate an email in one line, use filter_var() function !
    http://fr.php.net/manual/en/function.filter-var.php

    easy use, as described in the document example :
    var_dump(filter_var('bob@example.com', FILTER_VALIDATE_EMAIL));
    ian_channing at hotmail dot com
    6 years ago
    This is a function that uses regular expressions to match against the various VAT formats required across the EU.

    <?php
    /**
    * @param integer $country Country name
    * @param integer $vat_number VAT number to test e.g. GB123 4567 89
    * @return integer -1 if country not included OR 1 if the VAT Num matches for the country OR 0 if no match
    */
    function checkVatNumber( $country, $vat_number ) {
        switch(    $country) {
            case     'Austria':
                    $regex = '/^(AT){0,1}U[0-9]{8}$/i';
                break;
            case     'Belgium':
                    $regex = '/^(BE){0,1}[0]{0,1}[0-9]{9}$/i';
                break;
            case     'Bulgaria':
                    $regex = '/^(BG){0,1}[0-9]{9,10}$/i';
                break;
            case     'Cyprus':
                    $regex = '/^(CY){0,1}[0-9]{8}[A-Z]$/i';
                break;
            case     'Czech Republic':
                    $regex = '/^(CZ){0,1}[0-9]{8,10}$/i';
                break;
            case     'Denmark':
                    $regex = '/^(DK){0,1}([0-9]{2}[\ ]{0,1}){3}[0-9]{2}$/i';
                break;
            case     'Estonia':
            case     'Germany':
            case     'Greece':
            case     'Portugal':
                    $regex = '/^(EE|EL|DE|PT){0,1}[0-9]{9}$/i';
                break;
            case     'France':
                    $regex = '/^(FR){0,1}[0-9A-Z]{2}[\ ]{0,1}[0-9]{9}$/i';
                break;
            case     'Finland':
            case     'Hungary':
            case     'Luxembourg':
            case     'Malta':
            case     'Slovenia':
                    $regex = '/^(FI|HU|LU|MT|SI){0,1}[0-9]{8}$/i';
                break;
            case     'Ireland':
                    $regex = '/^(IE){0,1}[0-9][0-9A-Z\+\*][0-9]{5}[A-Z]$/i';
                break;
            case     'Italy':
            case     'Latvia':
                    $regex = '/^(IT|LV){0,1}[0-9]{11}$/i';
                break;
            case     'Lithuania':
                    $regex = '/^(LT){0,1}([0-9]{9}|[0-9]{12})$/i';
                break;
            case     'Netherlands':
                    $regex = '/^(NL){0,1}[0-9]{9}B[0-9]{2}$/i';
                break;
            case     'Poland':
            case     'Slovakia':
                    $regex = '/^(PL|SK){0,1}[0-9]{10}$/i';
                break;
            case     'Romania':
                    $regex = '/^(RO){0,1}[0-9]{2,10}$/i';
                break;
            case     'Sweden':
                    $regex = '/^(SE){0,1}[0-9]{12}$/i';
                break;
            case     'Spain':
                    $regex = '/^(ES){0,1}([0-9A-Z][0-9]{7}[A-Z])|([A-Z][0-9]{7}[0-9A-Z])$/i';
                break;
            case     'United Kingdom':
                    $regex = '/^(GB){0,1}([1-9][0-9]{2}[\ ]{0,1}[0-9]{4}[\ ]{0,1}[0-9]{2})|([1-9][0-9]{2}[\ ]{0,1}[0-9]{4}[\ ]{0,1}[0-9]{2}[\ ]{0,1}[0-9]{3})|((GD|HA)[0-9]{3})$/i';
                break;
            default:
                return -    1;
                break;
        }
       
        return     preg_match($regex, $vat_number);
    }
    ?>
    sainnr at gmail dot com
    5 years ago
    This sample regexp may be useful if you are working with DB field types.

    (?P<type>\w+)($|\((?P<length>(\d+|(.*)))\))

    For example, if you are have a such type as "varchar(255)" or "text", the next fragment

    <?php
       $type     = 'varchar(255)';  // type of field
           preg_match('/(?P<type>\w+)($|\((?P<length>(\d+|(.*)))\))/', $type, $field);
           print_r($field);
    ?>

    will output something like this:
    Array ( [0] => varchar(255) [type] => varchar [1] => varchar [2] => (255) [length] => 255 [3] => 255 [4] => 255 )
    skds1433 at hotmail dot com
    7 years ago
    here is a small tool for someone learning to use regular expressions. it's very basic, and allows you to try different patterns and combinations. I made it to help me, because I like to try different things, to get a good understanding of how things work.

    <?php
    $search     = isset($_POST['search'])?$_POST['search']:"//";
    $match = isset($_POST['match'])?$_POST['match']:"<>";

    echo     '<form method="post">';
    echo     's: <input style="width:400px;" name="search" type="text" value="'.$search.'" /><br />';
    echo     'm:<input style="width:400px;" name="match" type="text" value="'.$match.'" /><input type="submit" value="go" /></form><br />';
    if (    preg_match($search, $match)){echo "matches";}else{echo "no match";}
    ?>
    akniep at rayo dot info
    7 years ago
    Bugs of preg_match (PHP-version 5.2.5)

    In most cases, the following example will show one of two PHP-bugs discovered with preg_match depending on your PHP-version and configuration.

    <?php

    $text     = "test=";
    // creates a rather long text
    for ($i = 0; $i++ < 100000;)
            $text .= "%AB";

    // a typical URL_query validity-checker (the pattern's function does not matter for this example)
    $pattern    = '/^(?:[;\/?:@&=+$,]|(?:[^\W_]|[-_.!~*\()\[\] ])|(?:%[\da-fA-F]{2}))*$/';
       
    var_dump( preg_match( $pattern, $text ) );

    ?>

    Possible bug (1):
    =============
    On one of our Linux-Servers the above example crashes PHP-execution with a C(?) Segmentation Fault(!). This seems to be a known bug (see http://bugs.php.net/bug.php?id=40909), but I don't know if it has been fixed, yet.
    If you are looking for a work-around, the following code-snippet is what I found helpful. It wraps the possibly crashing preg_match call by decreasing the PCRE recursion limit in order to result in a Reg-Exp error instead of a PHP-crash.

    <?php
    [...]

    // decrease the PCRE recursion limit for the (possibly dangerous) preg_match call
    $former_recursion_limit = ini_set( "pcre.recursion_limit", 10000 );

    // the wrapped preg_match call
    $result = preg_match( $pattern, $text );

    // reset the PCRE recursion limit to its original value
    ini_set( "pcre.recursion_limit", $former_recursion_limit );

    // if the reg-exp fails due to the decreased recursion limit we may not make any statement, but PHP-execution continues
    if ( PREG_RECURSION_LIMIT_ERROR === preg_last_error() )
    {
            // react on the failed regular expression here
            $result = [...];
       
            // do logging or email-sending here
            [...]
    }     //if

    ?>

    Possible bug (2):
    =============
    On one of our Windows-Servers the above example does not crash PHP, but (directly) hits the recursion-limit. Here, the problem is that preg_match does not return boolean(false) as expected by the description / manual of above.
    In short, preg_match seems to return an int(0) instead of the expected boolean(false) if the regular expression could not be executed due to the PCRE recursion-limit. So, if preg_match results in int(0) you seem to have to check preg_last_error() if maybe an error occurred.
    Kae Cyphet
    6 years ago
    for those coming over from ereg, preg_match can be quite intimidating. to get started here is a migration tip.

    <?php
    if(ereg('[^0-9A-Za-z]',$test_string)) // will be true if characters arnt 0-9, A-Z or a-z.

    if(preg_match('/[^0-9A-Za-z]/',$test_string)) // this is the preg_match version. the /'s are now required.
    ?>
    splattermania at freenet dot de
    6 years ago
    As I wasted lots of time finding a REAL regex for URLs and resulted in building it on my own, I now have found one, that seems to work for all kinds of urls:

    <?php
        $regex     = "((https?|ftp)\:\/\/)?"; // SCHEME
            $regex .= "([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?"; // User and Pass
            $regex .= "([a-z0-9-.]*)\.([a-z]{2,3})"; // Host or IP
            $regex .= "(\:[0-9]{2,5})?"; // Port
            $regex .= "(\/([a-z0-9+\$_-]\.?)+)*\/?"; // Path
            $regex .= "(\?[a-z+&\$_.-][a-z0-9;:@&%=+\/\$_.-]*)?"; // GET Query
            $regex .= "(#[a-z_.-][a-z0-9+\$_.-]*)?"; // Anchor
    ?>

    Then, the correct way to check against the regex ist as follows:

    <?php
               if(preg_match("/^$regex$/", $url))
           {
                   return     true;
           }
    ?>
    Gilles A
    1 year ago
    Using named subpattern :

    Since PCRE 7.0 ( PHP  >= 5.2.2) , named groups can be defined using
    (?<name>) or (?'name') instead of (?P<name>)

    <?php

    $str     = 'foobar: 2008';

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

    print_r($matches);

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

    print_r($matches);

    //Or

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

    print_r($matches);
    ?>

    //Result

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

    Array
    (
        [0] => foobar: 2008
        [name] => foobar
        [1] => foobar
        [digit] => 2008
        [2] => 2008
    )
    Array
    (
        [0] => foobar: 2008
        [name] => foobar
        [1] => foobar
        [digit] => 2008
        [2] => 2008
    )
    ulli dot luftpumpe at murkymind dot de
    4 years ago
    Matching a backslash character can be confusing, because double escaping is needed in the pattern: first for PHP, second for the regex engine
    <?php
    //match newline control character:
    preg_match('/\n/','\n');   //pattern matches and is stored as control character 0x0A in the pattern string
    preg_match('/\\\n/','\n'); //very same match, but is stored escaped as 0x5C,0x6E in the pattern string

    //trying to match "\'" (2 characters) in a text file, '\\\'' as PHP string:
    $subject = file_get_contents('myfile.txt');
    preg_match('/\\\'/',$subject);    //DOESN'T MATCH!!! stored as 0x5C,0x27 (escaped apostrophe), this only matches apostrophe
    preg_match('/\\\\\'/',$subject);  //matches, stored as 0x5C,0x5C,0x27 (escaped backslash and unescaped apostrophe)
    preg_match('/\\\\\\\/',$subject); //also matches, stored as 0x5C,0x5C,0x5C,0x27 (escaped backslash and escaped apostrophe)

    //matching "\n" (2 characters):
    preg_match('/\\\\n/','\\n');
    preg_match('/\\\n/','\\n'); //same match - 3 backslashes are interpreted as 2 in PHP, if the following character is not escapeable
    ?>
    Anonymous
    3 years ago
    Here is a function that decreases the numbers inside a string (useful to convert DOM object into simplexml object)

    e.g.: decremente_chaine("somenode->anode[2]->achildnode[3]") will return "somenode->anode[1]->achildnode[2]"

    the numbering of the nodes in simplexml starts from zero, but from 1 in DOM xpath objects

    <?php
    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;
        }
    ?>
    jphansen at uga dot edu
    3 years ago
    Here's a regex to validate against the schema for common MySQL
    identifiers:

    <?php
    $string     = "$table_name";
    if (    preg_match("/[^\\d\\sa-zA-Z$_]/", $string))
      echo     "Failed validation";
    ?>
    ayman2243 at gmail dot com
    4 years ago
    highlight Search Words

    <?php
    function highlight($word, $subject) {
       
            $split_subject = explode(" ", $subject);
            $split_word = explode(" ", $word);

        foreach (    $split_subject as $k => $v){
               foreach (    $split_word as $k2 => $v2){
                   if(    $v2 == $v){
                      
                           $split_subject[$k] = "<span class='highlight'>".$v."</span>";
                  
                   }
               }
          }
         
          return     implode(' ', $split_subject);
    }
    ?>
    yofilter-php at yahoo dot co dot uk
    3 years ago
    There does not seem to be any mention of the PHP version of switches that can be used with regular expressions.

    preg_match_all('/regular expr/sim',$text).

    The s i m being the location for and available switches (I know about)
    The i is to ignore letter cases (this is commonly known - I think)
    The s tells the code NOT TO stop searching when it encounters \n (line break) - this is important with multi-line entries for example text from an editor that needs search.
    The m tells the code it is a multi-line entry, but importantly allows the use of ^ and $ to work when showing start and end.

    I am hoping this will save someone from the 4 hours of torture that I endured, trying to workout this issue.
    SoN9ne at gmail dot com
    5 years ago
    I have been working on a email system that will automatically generate a text email from a given HTML email by using strip_tags().
    The only issue I ran into, for my needs, were that the anchors would not keep their links.
    I search for a little while and could not find anything to strip the links from the tags so I generated my own little snippet.
    I am posting it here in hopes that others may find it useful and for later reference.

    A note to keep in mind:
    I was primarily concerned with valid HTML so if attributes do no use ' or " to contain the values then this will need to be tweaked.
    If you can edit this to work better, please let me know.
    <?php
    /**
    * Replaces anchor tags with text
    * - Will search string and replace all anchor tags with text (case insensitive)
    *
    * How it works:
    * - Searches string for an anchor tag, checks to make sure it matches the criteria
    *         Anchor search criteria:
    *             - 1 - <a (must have the start of the anchor tag )
    *             - 2 - Can have any number of spaces or other attributes before and after the href attribute
    *             - 3 - Must close the anchor tag
    *
    * - Once the check has passed it will then replace the anchor tag with the string replacement
    * - The string replacement can be customized
    *
    * Know issue:
    * - This will not work for anchors that do not use a ' or " to contain the attributes.
    *         (i.e.- <a href=http: //php.net>PHP.net</a> will not be replaced)
    */
    function replaceAnchorsWithText($data) {
            /**
         * Had to modify $regex so it could post to the site... so I broke it into 6 parts.
         */
            $regex  = '/(<a\s*'; // Start of anchor tag
            $regex .= '(.*?)\s*'; // Any attributes or spaces that may or may not exist
            $regex .= 'href=[\'"]+?\s*(?P<link>\S+)\s*[\'"]+?'; // Grab the link
            $regex .= '\s*(.*?)\s*>\s*'; // Any attributes or spaces that may or may not exist before closing tag
            $regex .= '(?P<name>\S+)'; // Grab the name
            $regex .= '\s*<\/a>)/i'; // Any number of spaces between the closing anchor tag (case insensitive)
       
            if (is_array($data)) {
                // This is what will replace the link (modify to you liking)
                $data = "{$data['name']}({$data['link']})";
        }
        return     preg_replace_callback($regex, 'replaceAnchorsWithText', $data);
    }

    $input  = 'Test 1: <a href="http: //php.net1">PHP.NET1</a>.<br />';
    $input .= 'Test 2: <A name="test" HREF=\'HTTP: //PHP.NET2\' target="_blank">PHP.NET2</A>.<BR />';
    $input .= 'Test 3: <a hRef=http: //php.net3>php.net3</a><br />';
    $input .= 'This last line had nothing to do with any of this';

    echo     replaceAnchorsWithText($input).'<hr/>';
    ?>
    Will output:
    Test 1: PHP.NET1(http: //php.net1).
    Test 2: PHP.NET2(HTTP: //PHP.NET2).
    Test 3: php.net3 (is still an anchor)
    This last line had nothing to do with any of this

    Posting to this site is painful...
    Had to break up the regex and had to break the test links since it was being flagged as spam...
    teracci2002
    6 years ago
    When you use preg_match() for security purpose or huge data processing,
    mayby you should make consideration for backtrack_limit and recursion_limit.
    http://www.php.net/manual/en/pcre.configuration.php

    These limits may bring wrong matching result.
    You can verify whether you hit these limits by checking preg_last_error().
    http://www.php.net/manual/en/function.preg-last-error.php
    ruakuu at NOSPAM dot com
    6 years ago
    Was working on a site that needed japanese and alphabetic letters and needed to
    validate input using preg_match, I tried using \p{script} but didn't work:

    <?php
    $pattern     ='/^([-a-zA-Z0-9_\p{Katakana}\p{Hiragana}\p{Han}]*)$/u'; // Didn't work
    ?>

    So I tried with ranges and it worked:

    <?php
    $pattern     ='/^[-a-zA-Z0-9_\x{30A0}-\x{30FF}'
                 .'\x{3040}-\x{309F}\x{4E00}-\x{9FBF}\s]*$/u';
    $match_string = '印刷最安 ニキビ跡除去 ゲームボーイ';

    if (    preg_match($pattern, $match_string)) {
        echo     "Found - pattern $pattern";
    } else {
        echo     "Not found - pattern $pattern";
    }
    ?>

    U+4E00–U+9FBF Kanji
    U+3040–U+309F Hiragana
    U+30A0–U+30FF Katakana

    Hope its useful, it took me several hours to figure it out.
    Anonymous
    6 years ago
    If your regular expression does not match with long input text when you think it should, you might have hit the PCRE backtrack default limit of 100000. See http://php.net/pcre.backtrack-limit.
    Alex Zinchenko
    7 years ago
    If you need to check whether string is a serialized representation of variable(sic!) you can use this :

    <?php

    $string     = "a:0:{}";
    if(    preg_match("/(a|O|s|b)\x3a[0-9]*?
    ((\x3a((\x7b?(.+)\x7d)|(\x22(.+)\x22\x3b)))|(\x3b))/"    , $string))
    {
    echo     "Serialized.";
    }
    else
    {
    echo     "Not serialized.";
    }

    ?>

    But don't forget, string in serialized representation could be VERY big,
    so match work can be slow, even with fast preg_* functions.
    Ashus
    7 years ago
    If you need to match specific wildcards in IP address, you can use this regexp:

    <?php

    $ip     = '10.1.66.22';
    $cmp = '10.1.??.*';

    $cnt = preg_match('/^'
             .str_replace(
         array(    '\*','\?'),
         array(    '(.*?)','[0-9]'),
             preg_quote($cmp)).'$/',
             $ip);

    echo     $cnt;

    ?>

    where '?' is exactly one digit and '*' is any number of any characters. $cmp mask can be provided wild by user, $cnt equals (int) 1 on match or 0.
    plasma
    6 years ago
    To extract scheme, host, path, ect. simply use

    <?php

      $url      = 'http://name:pass@';
          $url .= 'example.com:10000';
          $url .= '/path/to/file.php?a=1&amp;b=2#anchor';

          $url_data = parse_url ( $url );

          print_r ( $url_data );

    ?>
    ___
    prints out something like:

    Array
    (
        [scheme] => http
        [host] => wild.subdomain.orgy.domain.co.uk
        [port] => 10000
        [user] => name
        [pass] => pass
        [path] => /path/to/file.php
        [query] => a=1&b=2
        [fragment] => anchor
    )

    In my tests parse_url is up to 15x faster than preg_match(_all)!
    wjaspers4 [at] gmail [dot] com
    7 years ago
    I recently encountered a problem trying to capture multiple instances of named subpatterns from filenames.
    Therefore, I came up with this function.

    The function allows you to pass through flags (in this version it applies to all expressions tested), and generates an array of search results.

    Enjoy!

    <?php

    /**
    * Allows multiple expressions to be tested on one string.
    * This will return a boolean, however you may want to alter this.
    *
    * @author William Jaspers, IV <wjaspers4@gmail.com>
    * @created 2009-02-27 17:00:00 +6:00:00 GMT
    * @access public
    *
    * @param array $patterns An array of expressions to be tested.
    * @param String $subject The data to test.
    * @param array $findings Optional argument to store our results.
    * @param mixed $flags Pass-thru argument to allow normal flags to apply to all tested expressions.
    * @param array $errors A storage bin for errors
    *
    * @returns bool Whether or not errors occurred.
    */
    function preg_match_multiple(
      array     $patterns=array(),
          $subject=null,
      &    $findings=array(),
          $flags=false,
      &    $errors=array()
    ) {
      foreach(     $patterns as $name => $pattern )
      {
        if(     1 <= preg_match_all( $pattern, $subject, $found, $flags ) )
        {
              $findings[$name] = $found;
        } else
        {
          if(     PREG_NO_ERROR !== ( $code = preg_last_error() ))
          {
                $errors[$name] = $code;
          } else     $findings[$name] = array();
        }
      }
      return (    0===sizeof($errors));
    }
    ?>
    Jeff Weiss
    2 years ago
    Example of validating an email address and breaking it into 3 parts ( local, domain name, domain suffix )

    A case insensitive  email is valid if:

    1) local matches letters a..z or characters . - _ +
    2) domain name matches letters a..z or characters - _
    3) domain suffix matches letters a..z and is between 2 and 4 characters in length

    <?php
    preg_match    ('/(^[a-zA-Z_.+-]+)@([a-zA-Z_-]+).([a-zA-Z]{2,4}$)/i', "jeff@nowhere.com", $matches);

    var_export($matches);
    ?>

    outputs:

    Array
    (
        [0] => jeff@nowhere.com
        [1] => jeff
        [2] => nowhere
        [3] => com
    )
    Nimja
    4 years ago
    When using a 'bad words reject string' filter, preg_match is MUCH faster than strpos / stripos. Because in the other cases, you would need to do a foreach for each word. With efficient programming, the foreach is ONLY faster when the first word in the ban-list is found.

    (for 12 words, 100,000 iterations, no word found)
    stripos - Taken 1.4876 seconds.
    strpos - Taken 1.4207 seconds.
    preg_match - Taken 0.189 seconds.

    Interesting fact:
    With long words ('averylongwordtospitepreg'), the difference is only much less. Only about a 2/3rd of the time instead of 1/6th

    <?php

    $words     = array('word1', 'word2', 'word3', 'word4', 'word5', 'word6', 'word7', 'word8', 'word9', 'word10', 'word11', 'word12' );
    $teststring = 'ThIs Is A tEsTsTrInG fOr TeStInG.';
    $count = 100000;
    $find = 0;

    $start = microtime(TRUE);
    for (    $i = 0; $i < $count; $i++) {
        foreach (    $words as $word) {
            if (    stripos($teststring, $word) !== FALSE) {
                    $find++;
                break;
            }
        }
    }
    echo     'stripos - Taken ' . round(microtime(TRUE) - $start, 4) . ' seconds.' . PHP_EOL;

    $start = microtime(TRUE);
    for (    $i = 0; $i < $count; $i++) {
        foreach (    $words as $word) {
            if (    strpos($teststring, $word) !== FALSE) {
                    $find++;
                break;
            }
        }
    }
    echo     'strpos - Taken ' . round(microtime(TRUE) - $start, 4) . ' seconds.' . PHP_EOL;

    $start = microtime(TRUE);
    $pattern = '/';
    $div = '';
    foreach (    $words as $word) {
            $pattern .= $div . preg_quote($word);
            $div = '|';
    }
    $pattern .= '/i';
    //Pattern could easily be done somewhere else if words are static.
    for ($i = 0; $i < $count; $i++) {
        if (    preg_match($pattern, $teststring)) {
                $find++;
        }
    }
    $end = microtime(TRUE);
    echo     'preg_match - Taken ' . round($end - $start, 4) . ' seconds.' . PHP_EOL;
    ?>
    cmallabon at homesfactory dot com
    4 years ago
    Just an interesting note. Was just updating code to replace ereg() with strpos() and preg_match and the thought occured that preg_match() could be optimized to quit early when only searching if a string begins with something, for example
    <?php
    if(preg_match("/^http/", $url))
    {
    //do something
    }
    ?>

    vs

    <?php
    if(strpos($url, "http") === 0)
    {
    //do something
    }
    ?>

    As I guessed, strpos() is always faster (about 2x) for short strings like a URL but for very long strings of several paragraphs (e.g. a block of XML) when the string doesn't start with the needle preg_match as twice as fast as strpos() as it doesn't scan the entire string.

    So, if you are searching long strings and expect it to normally be true (e.g. validating XML), strpos() is a much faster BUT if you expect if to often fail, preg_match is the better choice.
    Frank
    5 years ago
    If someone is from a country that accepts decimal numbers in format 9.00 and 9,00 (point or comma), number validation would be like that:
    <?php
    $number_check     = "9,99";
    if (    preg_match( '/^[\-+]?[0-9]*\.*\,?[0-9]+$/', $number_check)) {
        return     TRUE;
    }
    ?>

    However, if the number will be written in the database, most probably this comma needs to be replaced with a dot.
    This can be done with use of str_replace, i.e :
    <?php
    $number_database     = str_replace("," , "." , $number_check);
    ?>
    matt
    6 years ago
    To support large Unicode ranges (ie: [\x{E000}-\x{FFFD}] or \x{10FFFFF}) you must use the modifier '/u' at the end of your expression.
    Dino Korah AT webroot DOT com
    7 years ago
    preg_match and preg_replace_callback doesnt match up in the structure of the array that they fill-up for a match.
    preg_match, as the example shows, supports named patterns, whereas preg_replace_callback doesnt seem to support it at all. It seem to ignore any named pattern matched.
    andre at koethur dot de
    2 years ago
    Be aware of bug https://bugs.php.net/bug.php?id=50887 when using sub patterns: Un-matched optional sub patterns at the end won't show up in $matches.

    Here is a workaround: Assign a name to all subpatterns you are interested in, and merge $match afterwards with an constant array containing some reasonable default values:

    <?php
    if (preg_match('/^(?P<lang>[^;*][^;]*){1}(?:;q=(?P<qval>[0-9.]+))?$/u', 'de', $match))
    {
          $match = array_merge(array('lang' => '', 'qval' => ''), $match);
          print_r($match);
    }
    ?>

    This outputs:
    Array
    (
        [lang] => de
        [qval] =>
        [0] => de
        [1] => de
    )

    Instead of:
    Array
    (
        [0] => de
        [lang] => de
        [1] => de
    )
    Validate PAN Number
    4 years ago
    Validate PAN Number.
    [5 Alpha][4 Number][1 Alpha]
    AAAAA1111A

    function isValidPAN($num){
        return preg_match("/^[A-Z]{5}[0-9]{4}[A-Z]{1}$/", $num);
    }
    workhorse at op dot pl
    4 years ago
    Preg_match returns empty result trying to validate $subject with carriege returns (/n/r).
    To solve it one need to use /s modifier in $pattern string.
    <?php
    $pattern    ='/.*/s';
    $valid=preg_match($pattern, $subject, $match);
    ?>
    Anonymous
    6 years ago
    The regular expression for breaking-down a URI reference into its components:

          ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
           12            3  4          5       6  7        8 9

    Source: ietf.org/rfc/rfc2396.txt
    Stefan
    6 years ago
    I spent a while replacing all my ereg() calls to preg_match(), since ereg() is now deprecated and will not be supported as of v 6.0.

    Just a warning regarding the conversion, the two functions behave very similarly, but not exactly alike. Obviously, you will need to delimit your pattern with '/' or '|' characters.

    The difference that stumped me was that preg_replace overwrites the $matches array regardless if a match was found. If no match was found, $matches is simply empty.

    ereg(), however, would leave $matches alone if a match was not found. In my code, I had repeated calls to ereg, and was populating $matches with each match. I was only interested in the last match. However, with preg_match, if the very last call to the function did not result in a match, the $matches array would be overwritten with a blank value.

    Here is an example code snippet to illustrate:

    <?php
    $test     = array('yes','no','yes','no','yes','no');

    foreach (    $test as $key=>$value) {
          ereg("yes",$value,$matches1);
          preg_match("|yes|",$value,$matches2);
    }
      print     "ereg result: $matches1[0]<br>";
      print     "preg_match result: $matches2[0]<br>";
    ?>

    The output is:
    ereg result: yes
    preg_match result:

    ($matches2[0] in this case is empty)

    I believe the preg_match behavior is cleaner. I just thought I would report this to hopefully save others some time.
    hessemanj2100 at gmail dot com
    2 years ago
    The most accurate IPv4 function. It will not allow leading zeros and supports the full address range of 0.0.0.0 - 255.255.255.255

    <?php
    function is_ipv4($string)
    {
            // The regular expression checks for any number between 0 and 255 beginning with a dot (repeated 3 times)
        // followed by another number between 0 and 255 at the end. The equivalent to an IPv4 address.
            return (bool) preg_match('/^(?:(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])'.
            '\.){3}(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]?|[0-9])$/', $string);
    }
    ?>
    phil dot taylor at gmail dot com
    7 years ago
    If you need to check for .com.br and .com.au and .uk and all the other crazy domain endings i found the following expression works well if you want to validate an email address. Its quite generous in what it will allow

    <?php

            $email_address     = "phil.taylor@a_domain.tv";

        if (    preg_match("/^[^@]*@[^@]*\.[^@]*$/", $email_address)) {
            return     "E-mail address";       
        }
           
    ?>
    mulllhausen
    4 years ago
    i do a fair bit of html scraping in conjunction with curl. i always need to know if i have reached the right page or if the curl request failed. the main problem i have encountered is html tags having unexpected spaces or other characters (especially the &nbsp; character sequence) between them. for example when requesting a page with a certain manner set of post or get variables the response might be

    <a href='blah'><span>data data data</span></a>

    but requesting the same page with different post/get variables might give the following result:

    <a href='blah'>
             &nbsp;<span>data data data</span>
    </a>

    to match both of these tag sequences with the same pattern i use the [\S\s]*? wildcard which basically means 'match anything at all...but not if you can help it'

    so the pattern for the above sequence would be:

    <?php

    $page1     = "........<a href='blah'><span>data data data</span></a>.........";

    $page2 = "........<a href='blah'>
             &nbsp;<span>data data data</span>
    </a>
    ........"    ;

    $w = "[\s\S]*?"; //ungreedy wildcard
    $pattern = "/\<a href='blah'\>$w\<span\>data data data\<\/span\>$w\<\/a\>/";

    if(    preg_match($pattern, $page1, $matches)) echo "got to page 1. match: [".print_r($matches, true)."]\n";
    else echo     "did not get to page 1\n";

    if(    preg_match($pattern, $page2, $matches)) echo "got to page 2. match: [".print_r($matches, true)."]\n";
    else echo     "did not get to page 2\n";

    ?>
    itworkarounds at gmail dot com
    4 years ago
    You can use the following code to detect non-latin (Cyrilic, Arabic, Greek...) characters:

    <?php
    preg_match    ("/^[a-zA-Z\p{Cyrillic}0-9\s\-]+$/u", "ABC abc 1234 АБВ абв");
    ?>
    Julius
    2 months ago
    Regarding utf-8 and offset:
    Be aware that the 5th Parameter behaves in the same way as the 4th is handeled. The $offset parameter should therefore be given as byte length.

    <?php
    var_dump    (preg_match('/#/u', 'a#',$matches,0,2));
    var_dump(preg_match('/#/u', "\xc3\xa4#",$matches,0,2));
    var_dump(preg_match('/#/u', "\xc3\xa4#",$matches,0,3));
    ?>
    bstefanovic at outlook dot com
    1 month ago
    This tool really helped me achieve the best possible results with this function: http://wordpresstester.com/
    Supriya Karmakar Kolkata
    1 year ago
    Always escape double quotes to avoid errors, even if you don't need to.

    bad practice:
    $foo = preg_match('/<h2 class="bengali">.*?<\/h2>/', $bigTextChunk, $myArray);

    good practice:
    $foo = preg_match("/<h2 class=\"bengali\">.*?<\/h2>/", bigTextChunk, $myArray);

    Bad practice can cause mysterious errors as it happened in my case.
    dkr at dotnull dot de
    1 year ago
    I noted that PCRE_ANCHORED (the pattern modifier A) does work fine if using an offset. If you use the escape sequence \A or even the dash "^" in the regex, it does not work (even if in multiline mode)...

    <?php
    $text     = 'foo bar';
    print (int)     preg_match('/^bar/',$text,$a,null,4); // prints 0
    print (int) preg_match('/\Abar/',$text,$a,null,4); // prints 0
    print (int) preg_match('/bar/A',$text,$a,null,4); // prints 1
    ?>

    Hope this helps someone out there! :-)

    Version: PHP 5.5.12
    asdfasdasad34535 at iflow dot at
    2 years ago
    Attention! PREG_OFFSET_CAPTURE not UTF-8 aware when using u modifier
    and it's not a but, it's a feature:
    https://bugs.php.net/bug.php?id=37391

    Possible workaround: Use mb_strpos to get the correct offset, instead of the flag.

    UTF-8 support would be nice.
    hessemanj2100 at gmail dot com
    2 years ago
    Just a note about my last post. The regex expression for the function I posted contains a question mark at the end. Technically this doesn't need to be there but it will work with or without it. Just remove it if you don't want it. Enjoy!
    aer0s
    4 years ago
    Simple function to return a sub-string following the preg convention. Kind of expensive, and some might say lazy but it has saved me time.

    # preg_substr($pattern,$subject,[$offset]) function
    # @author   aer0s
    #  return a specific sub-string in a string using
    #   a regular expression
    # @param   $pattern   regular expression pattern to match
    # @param   $subject   string to search
    # @param   [$offset]   zero based match occurrence to return
    #                            
    # [$offset] is 0 by default which returns the first occurrence,
    # if [$offset] is -1 it will return the last occurrence

    function preg_substr($pattern,$subject,$offset=0){
        preg_match_all($pattern,$subject,$matches,PREG_PATTERN_ORDER);
        return $offset==-1?array_pop($matches[0]):$matches[0][$offset];
    }

    example:

                 $pattern = "/model(\s|-)[a-z0-9]/i";
                 $subject = "Is there something wrong with model 654, Model 732, and model 43xl or is Model aj45B the preferred choice?";

                 echo preg_substr($pattern,$subject);
                 echo preg_substr($pattern,$subject,1);
                 echo preg_substr($pattern,$subject,-1);

    Returns something like:

                 model 654
                 Model 732
                 Model aj45B
    sun at drupal dot org
    4 years ago
    Basic test for invalid UTF-8 that can hi-jack IE:

    <?php
    $valid     = (preg_match('/^./us', $text) == 1);
    ?>
    See http://api.drupal.org/api/drupal/includes--bootstrap.inc/function/drupal_validate_utf8/7 for details.

    ---

    Test for valid UTF-8 and XML/XHTML character range compatibility:

    <?php
    $invalid     = preg_match('@[^\x9\xA\xD\x20-\x{D7FF}\x{E000}-\x{FFFD}\x{10000}-\x{10FFFF}]@u', $text)
    ?>
    Ref: http://www.w3.org/TR/2000/REC-xml-20001006#charsets
    marcosc at tekar dot net
    6 years ago
    When using accented characters and "ñ" (áéíóúñ), preg_match does not work. It is a charset problem, use utf8_decode/decode to fix.
    daniel dot chcouri at gmail dot com
    6 years ago
    Html tags delete using regular expression

    <?php
    function removeHtmlTagsWithExceptions($html, $exceptions = null){
        if(    is_array($exceptions) && !empty($exceptions))
        {
            foreach(    $exceptions as $exception)
            {
                    $openTagPattern  = '/<(' . $exception . ')(\s.*?)?>/msi';
                    $closeTagPattern = '/<\/(' . $exception . ')>/msi';

                    $html = preg_replace(
                    array(    $openTagPattern, $closeTagPattern),
                    array(    '||l|\1\2|r||', '||l|/\1|r||'),
                        $html
                    );
            }
        }

            $html = preg_replace('/<.*?>/msi', '', $html);

        if(    is_array($exceptions))
        {
                $html = str_replace('||l|', '<', $html);
                $html = str_replace('|r||', '>', $html);
        }

        return     $html;
    }

    // example:
    print removeHtmlTagsWithExceptions(<<<EOF
    <h1>Whatsup?!</h1>
    Enjoy <span style="text-color:blue;">that</span> script<br />
    <br />
    EOF
    , array(    'br'));
    ?>
    Steve Todorov
    7 years ago
    While I was reading the preg_match documentation I didn't found how to match an IP..
    Let's say you need to make a script that is working with ip/host and you want to show the hostname - not the IP.

    Well this is the way to go:

    <?php
    /* This is an ip that is "GET"/"POST" from somewhere */
    $ip = $_POST['ipOrHost'];

    if(    preg_match('/(\d+).(\d+).(\d+).(\d+)/',$ip))
          $host = gethostbyaddr($ip);
    else
          $host = gethostbyname($ip);

    echo     $host;
    ?>

    This is a really simple script made for beginners !
    If you'd like you could add restriction to the numbers.
    The code above will accept all kind of numbers and we know that IP address could be MAX 255.255.255.255 and the example accepts to 999.999.999.999.

    Wish you luck!

    Best wishes,
    Steve
    kevin
    4 years ago
    here is a little function to get an associative array instead of the numeric one.

    <?php
    function preg_match_assoc($pattern, $subject, $assoc, $flags = 0, $offset = 0) {
            $matches = array();
        eval(    'preg_match($pattern, $subject, $matches, $flags, $offset);');
            $n = 0;
        foreach(    $matches as $result) {
                $array[$assoc[$n]] = $result;
                $n++;
        }
        return     $array;
    }
    ?>

    example of use

    <?php

    $assocs     = array(
            'all',
            'a-1',
            'i-1',
            'a-2',
            'ia-1',
            'ia-2'
    );

    $test = preg_match_assoc('#([a-z]+)([0-9]+)([a-z]+)\-([a-z|0-9]+)\-([a-z|0-9]+)#', 'az45rt-df36qz-fg89ih', $assocs);

    // $test will contain :
    //
    // array
    //   'all' => string 'az45rt-df36qz-fg89ih' (length=20)
    //   'a-1' => string 'az' (length=2)
    //   'i-1' => string '45' (length=2)
    //   'a-2' => string 'rt' (length=2)
    //   'ia-1' => string 'df36qz' (length=6)
    //
    // Instead of :
    //
    // array
    //   0 => string 'az45rt-df36qz-fg89ih' (length=20)
    //   1 => string 'az' (length=2)
    //   2 => string '45' (length=2)
    //   2 => string 'rt' (length=2)
    //   4 => string 'df36qz' (length=6)
    //   5 => string 'fg89ih' (length=6)

    ?>
    Dr@ke
    6 years ago
    Hello,
    There is a bug with somes new PCRE versions (like:7.9 2009-04-1),
    In patterns:
    \w+ !== [a-zA-Z0-9]+

    But it's ok, if i replace \w+ by [a-z0-9]+ or [a-zA-Z0-9]+
    juanmadss at gmail dot com
    4 years ago
    Testing the speed of preg_match against stripos doing insensitive case search in strings:

    <?php
    $string     = "Hey, how are you? I'm a string.";

    // PCRE
    $start = microtime(true);
    for (    $i = 1; $i < 10000000; $i++) {
            $bool = preg_match('/you/i', $string);
    }
    $end = microtime(true);
    $pcre_lasted = $end - $start; // 8.3078360557556

    // Stripos, we believe in you
    $start = microtime(true);
    for (    $i = 1; $i < 10000000; $i++) {
            $bool = stripos($string, 'you') !== false;
    }
    $end = microtime(true);
    $stripos_lasted = $end - $start; // 6.0306038856506

    echo "Preg_match lasted: {$pcre_lasted}<br />Stripos lasted: {$stripos_lasted}";
    ?>

    So unless you really need to test a string against a regular expression, always use strpos / stripos and other string functions to find characters and strings within other strings.
    saberdream at live dot fr
    6 years ago
    I made a function to circumvent the problem of length of a string... This verifies that the link is an image.

    <?php
    function verifiesimage($lien, $limite) {
        if(     preg_match('#^http:\/\/(.*)\.(gif|png|jpg)$#i', $lien) && strlen($lien) < $limite )
        {
                $msg = TRUE; // link ok
            }
        else
        {
                $msg = FALSE; // the link isn't image
            }
        return     $msg; // return TRUE or FALSE
    }
    ?>

    Example :

    <?php
    if(verifierimage($votrelien, 50) == TRUE)
    {
            // we display the content...
    }
    ?>
    Iven Marquardt
    2 years ago
    if you want to match all printable ascii (0..127) expect some specific chars, try this:

    <?php
    $excluded     = '\$a';
    echo     preg_replace('~[^' . $excluded . '[:^print:]]~', '', 'abc123ABC!?$%/€');
    ?>

    result: a$€
    Rob
    6 years ago
    The following function works well for validating ip addresses

    <?php
    function valid_ip($ip) {
        return     preg_match("/^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])" .
                    "(\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}$/", $ip);
    }
    ?>
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