PHP 执行一个正则表达式匹配

版本	说明
5.3.6	如果 `offset` 比 `subject` 的长度还要大则返回 `FALSE`。
5.2.2	命名子组可以接受(?<name>)， (?'name') 以及(?P<name>)语法。之前版本仅接受(?P<name>)语法。
4.3.3	增加了参数`offset`.
4.3.0	增加了标记`PREG_OFFSET_CAPTURE`。
4.3.0	增加了参数`flags`。

用户评论:

hessemanj2100 at gmail dot com (2013-07-01 17:32:24)

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!

hessemanj2100 at gmail dot com (2013-07-01 17:05:37)

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); } ?>

andre at koethur dot de (2013-06-17 20:49:29)

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 )

yofilter-php at yahoo dot co dot uk (2013-03-05 13:48:11)

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.

Yousef Ismaeil Cliprz (2013-02-04 13:31:23)

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."; } ?>

Anonymous (2012-09-24 08:02:06)

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 (2012-05-22 19:41:48)

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"; ?>

ulli dot luftpumpe at murkymind dot de (2012-04-07 22:32:13)

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 ?>

Validate PAN Number (2012-03-30 10:13:04)

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); }

aer0s (2012-03-16 21:15:14)

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

Nimja (2012-02-10 11:12:01)

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; ?>

kevin (2012-01-08 06:11:33)

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) ?>

Jonny 5 (2011-12-07 09:55:15)

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]))); } ?>

force at md-t dot org (2011-09-25 23:38:30)

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

cmallabon at homesfactory dot com (2011-08-30 22:28:48)

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.

ayman2243 at gmail dot com (2011-08-30 16:55:15)

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); } ?>

Khalid_Moharram at hotmail dot com (2011-08-25 13:36:11)

Well for anyone looking for email validation, according to the RFC specifications (ONLY FOR ((ENGLISH ASCII)) E-Mails). <?php function email_valid($temp_email) { ######## Three functions to HELP ######## function valid_dot_pos($email) { $str_len = strlen($email); for($i=0; $i<$str_len; $i++) { $current_element = $email[$i]; if($current_element == "." && ($email[$i+1] == ".")) { return false; break; } else { } } return true; } function valid_local_part($local_part) { if(preg_match("/[^a-zA-Z0-9-_@.!#$%&'*\/+=?^`{\|}~]/", $local_part)) { return false; } else { return true; } } function valid_domain_part($domain_part) { if(preg_match("/[^a-zA-Z0-9@#\[\].]/", $domain_part)) { return false; } elseif(preg_match("/[@]/", $domain_part) && preg_match("/[#]/", $domain_part)) { return false; } elseif(preg_match("/[\[]/", $domain_part) || preg_match("/[\]]/", $domain_part)) { $dot_pos = strrpos($domain_part, "."); if(($dot_pos < strrpos($domain_part, "]")) || (strrpos($domain_part, "]") < strrpos($domain_part, "["))) { return true; } elseif(preg_match("/[^0-9.]/", $domain_part)) { return false; } else { return false; } } else { return true; } } // trim() the entered E-Mail $str_trimmed = trim($temp_email); // find the @ position $at_pos = strrpos($str_trimmed, "@"); // find the . position $dot_pos = strrpos($str_trimmed, "."); // this will cut the local part and return it in $local_part $local_part = substr($str_trimmed, 0, $at_pos); // this will cut the domain part and return it in $domain_part $domain_part = substr($str_trimmed, $at_pos); if(!isset($str_trimmed) || is_null($str_trimmed) || empty($str_trimmed) || $str_trimmed == "") { $this->email_status = "You must insert something"; return false; } elseif(!valid_local_part($local_part)) { $this->email_status = "Invalid E-Mail Address"; return false; } elseif(!valid_domain_part($domain_part)) { $this->email_status = "Invalid E-Mail Address"; return false; } elseif($at_pos > $dot_pos) { $this->email_status = "Invalid E-Mail Address"; return false; } elseif(!valid_local_part($local_part)) { $this->email_status = "Invalid E-Mail Address"; return false; } elseif(($str_trimmed[$at_pos + 1]) == ".") { $this->email_status = "Invalid E-Mail Address"; return false; } elseif(!preg_match("/[(@)]/", $str_trimmed) || !preg_match("/[(.)]/", $str_trimmed)) { $this->email_status = "Invalid E-Mail Address"; return false; } else { $this->email_status = ""; return true; } } ?>

workhorse at op dot pl (2011-08-11 12:53:25)

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); ?>

itworkarounds at gmail dot com (2011-08-09 09:08:09)

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"); ?>

mohammad40g at gmail dot com (2011-08-01 21:23:57)

This sample is for checking persian character: <?php preg_match("/[\x{0600}-\x{06FF}\x]{1,32}/u", '????'); ?>

sun at drupal dot org (2011-06-23 17:56:40)

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

juanmadss at gmail dot com (2011-05-25 04:00:45)

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.

mulllhausen (2011-05-16 01:57:51)

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   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'>  <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'>  <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"; ?>

MrBull (2011-03-20 07:32:57)

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.

arash dot hemmat at gmail dot com (2011-02-02 19:15:47)

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" , '??????????' );

Frank (2011-01-26 12:12:44)

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); ?>

sainnr at gmail dot com (2010-12-30 06:12:31)

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 )

ian_channing at hotmail dot com (2010-12-27 01:55:50)

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);

SoN9ne at gmail dot com (2010-06-08 10:10:58)

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 (2010-04-09 09:00:41)

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

Kae Cyphet (2010-03-17 18:29:09)

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. ?>

plasma (2010-02-21 16:53:34)

To extract scheme, host, path, ect. simply use <?php $url = 'http://name:pass@'; $url .= 'example.com:10000'; $url .= '/path/to/file.php?a=1&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)!

Dr@ke (2010-02-18 07:58:23)

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]+

saberdream at live dot fr (2010-02-10 15:53:19)

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... } ?>

Anonymous (2010-02-06 08:00:01)

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

cebelab at gmail dot com (2010-01-23 22:43:07)

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

Stefan (2009-11-17 14:47:45)

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.

ruakuu at NOSPAM dot com (2009-11-03 21:32:29)

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 (2009-10-12 02:24:10)

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.

splattermania at freenet dot de (2009-10-01 05:01:00)

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; } ?>

luc _ santeramo at t yahoo dot com (2009-09-03 07:46:49)

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));

marcosc at tekar dot net (2009-08-27 09:31:23)

When using accented characters and "?" (áéíóú?), preg_match does not work. It is a charset problem, use utf8_decode/decode to fix.

ian_channing at hotmail dot com (2009-08-20 06:13:46)

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); } ?>

Rob (2009-08-19 12:03:37)

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); } ?>

KOmaSHOOTER at gmx dot de (2009-08-09 06:12:12)

reading files from a dir without "." or ".." <?php $handle = opendir('content/pages/'); $pages = array(); while (false !== ($file = readdir($handle))) { $case=preg_match("/^[.]/",$file,$out, PREG_OFFSET_CAPTURE); //echo($case); if(!$case){ echo("$file<br />"); array_push($pages,$file); } } echo(count($pages)); ?>

matt (2009-05-08 13:07:56)

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.

daniel dot chcouri at gmail dot com (2009-05-03 06:09:03)

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')); ?>

corey [works at] effim [delete] .com (2009-04-24 20:52:27)

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 (2009-03-06 15:18:44)

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.

wjaspers4 [at] gmail [dot] com (2009-02-27 15:16:08)

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)); } ?>

skds1433 at hotmail dot com (2009-02-19 06:41:38)

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 (2009-01-30 03:05:41)

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.

Alex Zinchenko (2008-12-10 18:15:26)

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.

phil dot taylor at gmail dot com (2008-10-22 17:01:20)

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"; } ?>

Steve Todorov (2008-10-02 18:23:45)

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

Ashus (2008-09-12 08:18:33)

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.

wjaspers4[at]gmail[dot]com (2008-08-28 07:55:28)

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; } ?>

Dino Korah AT webroot DOT com (2008-07-08 16:11:36)

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.

jonathan dot lydall at gmail dot removethispart dot com (2008-05-26 12:50:00)

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"; } ?>

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