Regular expression Getting HTML Doctype

Question

My Html code is like this

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

or this can be like this

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">

I want to get the Doc Type which will be like "XHTML 1.0 Strict" (for the first one), and "HTML 4.0" (for the second one) from it. What will be the regular expression code for this? I like to use it in PHP preg_match() function.

Please help me in this case.

For HTML5 it's only ` `. Any regex you come up with will _fail_ for that case. — mmtauqir, Apr 24 '13 at 14:27
I just can't leave this question without pointing OP to this: http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags — Alfabravo, Apr 24 '13 at 14:30

score 3 · Accepted Answer · answered Apr 24 '13 at 14:28

3

If the doctypes will be in the form shown, you could use

'#(?<=<!DOCTYPE HTML PUBLIC "-//W3C//DTD )[^/]+#i'

So

preg_match('#(?<=<!DOCTYPE HTML PUBLIC "-//W3C//DTD )[^/]+#i', html, $match);  
echo $match[0];

answered Apr 24 '13 at 14:28

MikeM

13,156
2
34
47

Vyktor · Answer 2 · 2013-04-24T14:44:32.850

How about using DOMDocument and DOMDocumentType?

$xml = new DOMDocument(); 
$xml->loadHTMLFile($url);

$name = $xml->doctype->publicId; // -//W3C//DTD XHTML 1.0 Strict//EN

$doctype now contains following values:

DOMDocumentType Object
(
    [name] => html
    [entities] => (object value omitted)
    [notations] => (object value omitted)
    [publicId] => -//W3C//DTD XHTML 1.0 Strict//EN
    [systemId] => http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd
    [internalSubset] => 
    [nodeName] => html
    [nodeValue] => 
    [nodeType] => 10
    [parentNode] => (object value omitted)
    [childNodes] => 
    [firstChild] => 
    [lastChild] => 
    [previousSibling] => 
    [nextSibling] => (object value omitted)
    [attributes] => 
    [ownerDocument] => (object value omitted)
    [namespaceURI] => 
    [prefix] => 
    [localName] => 
    [baseURI] => 
    [textContent] => 
)

So you can now easily extract type:

$name = $xml->doctype->publicId;
$name = preg_replace('~.*//DTD(.*?)//.*~', '$1', $name);
echo $name;

Which will result into XHTML 1.0 Strict. Working phpfiddle example here.

score 1 · Answer 3 · answered Dec 16 '14 at 11:47

function contains($haystack, $needle){
    if (strpos($haystack,$needle) !== false) {
        return true;
    }else{
        return false;
    }
}
                $theDocType = "";
                $stringWithHTML = ""; // load some HTML in here from somewhere

                // Create DOM from HTML 
                $doc = new DOMDocument();
                //@$doc->loadHTMLFile("just_a_file.html");
                @$doc->loadHTML($stringWithHTML);

                // Grab document type
                $dtName = $doc->doctype->name;
                $dtPublic = $doc->doctype->publicId;
                if( $dtName="html" && $dtPublic!=""){           
                    // HTML or XHTML?
                    if(contains($dtPublic,"xhtml")){
                        $theDocType = "XHTML 1.0";
                    }else{
                        $theDocType = "HTML 4.01";
                    }
                    // Which type?
                    if(contains($dtPublic,"strict")){
                        $theDocType .= " (Strict)";
                    }elseif(contains($dtPublic,"transitional")){
                        $theDocType .= " (Transitional)";
                    }elseif(contains($dtPublic,"frameset")){
                        $theDocType .= " (Frameset)";
                    }else{
                        $theDocType = "XHTML 1.1"; // XHTML 1.1
                    }
                }else{
                    $theDocType = "HTML 5";
                }

                // Result
                echo $theDocType;

This will output things like:
XHTML 1.1
HTML 5
HTML 4.01 (Strict)

score 0 · Answer 4 · answered Apr 24 '13 at 14:27

0

Try this

<?php
   $html = file_get_contents("http://google.com");
   $html = str_replace("\n","",$html);
   $get_doctype = preg_match_all("/(<!DOCTYPE.+\">)<html/i",$html,$matches);
   $doctype = $matches[1][0];
?>

answered Apr 24 '13 at 14:27

Bogdan Burym

5,482
2
27
46

score 0 · Answer 5 · answered Apr 24 '13 at 14:28

0

'<!doctype.*?//dtd\s+([^/]*)//EN.*?dtd">'

That should work as pattern for your examples.

answered Apr 24 '13 at 14:28

TheNiceGuy

3,462
8
34
64

score 0 · Answer 6 · answered Apr 24 '13 at 15:59

This regular expression extracts everything between "DTD " and "/" without any syntax checking:

.*DTD\s+([^/]+)

This regular expression extracts the document type and checks some syntax in the string:

<!DOCTYPE\s+\w*\s*\w*\s*"[-//\w\d]*DTD\s+([\w\d\s.]*)[^"]*[^>]*>

score 0 · Answer 7 · answered Jan 22 '15 at 06:28

I used this thread in the past, but in testing process, I detected a problem with some large doctypes. Some times, the developer split the doctype in 2 or 3 lines. In this case, the usage of regular expression is no the best approach.

I paste an approach for doctypes in one or several lines:

<?
class Doctype {
    var $html;
    var $doctype;
    var $version;
    function Doctype($html){
       $this->html = $html;
       $this->extractDoctype();
       $this->processDoctype();
    }
    private function extractDoctype(){
        $preDoctype = "";
        $preDoctypeValid = false;
        $lines = explode(PHP_EOL, $this->html);
        foreach ($lines as &$line) {
            $preDoctype = $preDoctype . $line;
            if(
                (strpos(strtolower($preDoctype), "<!doctype") !== false) && 
                (strpos(strtolower($preDoctype), ">") !== false)){
                $preDoctypeValid = true;
                break;
            }
        }
        if($preDoctypeValid){
            //Store only the pattern: <! doctype >
            $pos1 = strpos(strtolower($preDoctype), "<!doctype");
            $pos2 = strpos($preDoctype, ">", $pos1) + 1;
            $preDoctype = substr($preDoctype, $pos1, $pos2);            
        }else{
            $preDoctype = "";
        }
        $this->doctype = $preDoctype;
    }
    private function processDoctype(){
        $version = "";

        $pattern_html5 = "/<!doctype\s+?html\s?>/i";
        if (preg_match($pattern_html5, strtolower($this->doctype))) {
            $version = "HTML5";
        }else if(strpos(strtolower($this->doctype), "xhtml") !== false){
            $version = "XHTML";     
        }else if(strpos(strtolower($this->doctype), "html") !== false){
            if(strpos(strtolower($this->doctype), "3.2") !== false){
                $version = "HTML 3.2";  
            }
            if(strpos(strtolower($this->doctype), "4.01") !== false){
                $version = "HTML 4.01"; 
            }
            if(strpos(strtolower($this->doctype), "2.0") !== false){
                $version = "HTML 2.0";  
            }
        }else{
            $version = "OTHER";
        }
        $this->version = $version;
    }
    public function getDoctype(){
        return $this->doctype;
    }
    public function getDoctypeVersion(){
        return $this->version;
    }
}
?>

https://github.com/jabrena/WTAnalyzer/blob/master/r_php/document/Doctype.class.php

Regular expression Getting HTML Doctype

7 Answers7