htmlspecialchars

add a note User Contributed Notes

MacIsaac
13-Apr-2006 04:05


<?php



// Escapes strings to be included in javascript

function jsspecialchars($s) {

    return preg_replace('/([^ !#$%@()*+,-.\x30-\x5b\x5d-\x7e])/e',

        "'\\x'.(ord('\\1')<16? '0': '').dechex(ord('\\1'))",$s);

}



?>



<script>

var some_variable = '<?= jsspecialchars($_GET['some_variable']) ?>';

</script>

richard at mf2fm dot com
03-Mar-2006 05:06


I had a script which detected swearing and wanted to make sure that words such as 'f &uuml; c k' didn't slip through the system.



After using htmlentities(), the following line converts most extended alphabet characters back to the standard alphabet so you can spot such problems..



$text=eregi_replace("&([a-z])[a-z0-9]{3,};", "\\\\1", $text);



This changes, for example, '&uuml;' into 'u' and '&szlig' into 's'.  Sadly it also converts '&pound;' and '&para;' into 'p' so it's not perfect but does solve a lot of the problems

mikiwoz at yahoo dot co dot uk
07-Oct-2005 05:40


I am not sure, maybe I'm missing something, but I have found something interesting:

I've been working on a project, where I had to use htmlspecialchars (for opbvious reasons). I olso needed to de-code the encoded string. What I have done was almost a copy and paste from php.net:

$trans=get_html_translation_table(HTML_SPECIALCHARS, ENT_QUOTES);

$trans=array_flip($trans);

$string=strtr($encoded, $trans);

(it looked a bit different in my code, but the idea is clear)

I couldn't get the apostrophe sign de-coded, and I needed it for the <A> tags. After an hour or so of debuging, I decided do print_r($trans). What I got was:

...

[&#39;] => '

...

BUT the apostrophe was encoded to $#039; -> note the zero.

I don't suppose it's a bug, but it definetely IS a potential pitfall, watch out for this one.

Luiz Miguel Axcar (lmaxcar at yahoo dot com dot br)
01-Sep-2005 09:16


Hello,



If you are getting trouble to SGDB write/read HTML data, try to use this:



<?php



//from html_entity_decode() manual page

function unhtmlentities ($string) {

   $trans_tbl =get_html_translation_table (HTML_ENTITIES );

   $trans_tbl =array_flip ($trans_tbl );

   return strtr ($string ,$trans_tbl );

}



//read from db

$content = stripslashes (htmlspecialchars ($field['content']));



//write to db

$content = unhtmlentities (addslashes (trim ($_POST['content'])));



//make sure result of function get_magic_quotes_gpc () == 0, you can get strange slashes in your content adding slashes twice



//better to do this using addslashes

$content = (! get_magic_quotes_gpc ()) ? addslashes ($content) : $content;



?>

jspalletta at gmail dot com
12-Jul-2005 08:37


I have found that this regular expression is sufficient for making sure that existing character entities show after htmlspecialchars() replaces _all_ occurrences of & with the &amp; entity.



<?php

// Note: hsc is an abbreviation of htmlspecialchars

function hscFixed($str)

{

    return preg_replace("/&amp;(#[0-9]+|[a-z]+);/i", "&$1;", htmlspecialchars($str));

}

?>



The only flaw I can think of is if you have text of the vein; "&[word];", that is not meant to be a character but rather uses the ampersand and semicolon in their traditional grammatical denotations.  However I think this is highly unlikely to occur (among other reasons, the fact that anyone with enough grammatical inclination to use them as such probably won't leave out the space between the ampersand and the word).

25-Jun-2005 11:44


You can't use htmlspecialchars to create RSS feeds, since it expands ampersands.You need to use something like this:

$content = preg_replace(array('/</', '/>/', '/"/'), array('&lt;', '&gt;', '&quot;'), $content);

palrich at gmail dot com
17-May-2005 04:29


To Alexander Nofftz and urbanheroes:

It's not an IE problem.  There is no &apos; in HTML.  So it's only a problem if someone else does render this as an apostraphe on an HTML page.

paul dot l at aon dot at
10-May-2005 12:50


function reverse_htmlentities($mixed)

{

    $htmltable = get_html_translation_table(HTML_ENTITIES);

    foreach($htmltable as $key => $value)

    {

        $mixed = ereg_replace(addslashes($value),$key,$mixed);

    }

    return $mixed;

}



this is my version of a reversed htmlentities function

thisiswherejunkgoes at gmail dot com
06-May-2005 01:06


If there're any n00bs out there looking for a way to ensure that no html/special chars are getting sent to their databases/put through forms/etc., this has been doing the trick for me (though being at least slightly n00bish, if this won't always work perhaps someone will ammend :-)



function checkforchars ($foo) {



  if ($foo === htmlspecialchars($foo)) {

        return "Valid entry.";

  } else {

        return "Invalid entry.";

  }



}

urbanheroes {at} gmail {dot} com
01-May-2005 02:32


In response to the note made by Alexander Nofftz on October 2004, &#39; is used instead of &apos; because IE unfortunately seems to have trouble with the latter.

gt at realvertex.com
29-Apr-2005 12:55


Here is the recursive version that works for both arrays and strings. Doesn't look as elegant as the other recursive versions, because of the input checks.



function HTML_ESC($_input = null, $_esc_keys = false)

{

    if ((null != $_input) && (is_array($_input)))

    {

        foreach($_input as $key => $value)

        {

            if($_esc_keys)

            {

                $_return[htmlspecialchars($key)] = HTML_ESC($value,$_esc_keys);

            }

            else

            {

                $_return[$key] = HTML_ESC($value);

            }

        }

        return $_return;

    }

    elseif(null != $_input)

    {

        return htmlspecialchars($_input);

    }

    else

    {

        return null;

    }

}

took
24-Apr-2005 12:14


The Algo from donwilson at gmail dot com to reverse the action of htmlspecialchars(), edited for germany:



function unhtmlspecialchars( $string )

{

  $string = str_replace ( '&amp;', '&', $string );

  $string = str_replace ( '&#039;', '\'', $string );

  $string = str_replace ( '&quot;', '"', $string );

  $string = str_replace ( '&lt;', '<', $string );

  $string = str_replace ( '&gt;', '>', $string );

  $string = str_replace ( '&uuml;', '', $string );

  $string = str_replace ( '&Uuml;', '', $string );

  $string = str_replace ( '&auml;', '', $string );

  $string = str_replace ( '&Auml;', '', $string );

  $string = str_replace ( '&ouml;', '', $string );

  $string = str_replace ( '&Ouml;', '', $string );    

  return $string;

}

11-Mar-2005 08:22


function htmlspecialchars_array($arr = array()) {

   $rs =  array();

   while(list($key,$val) = each($arr)) {

       if(is_array($val)) {

           $rs[$key] = htmlspecialchars_array($val);

       }

       else {

           $rs[$key] = htmlspecialchars($val, ENT_QUOTES);

       }    

   }

   return $rs;

}

beer UNDRSCR nomaed AT hotmail DOT com
01-Feb-2005 06:46


After inspecting the non-native encoding problem, I noticed that for example, if the encoding is cyrillic, and I write Latin characters that are not part of the encoding ( for example - ae-ligature), the browser will send the real entity, such as &aelig; for this case.

Therefore, the only way I see to display multilingual text that is encoded with entities is by:

<?php

    echo str_replace('&amp;', '&', htmlspecialchars($txt));

?>



The regex for numeric entities will skip the Latin-1 textual entities.

zolinak at zoli dot szathmari dot hu
14-Dec-2004 08:46


A sample function, if anybody want to turn html entities (and special characters) back to simple. (eg: "&egrave;", "<" etc)



function html2specialchars($str){

    $trans_table = array_flip(get_html_translation_table(HTML_ENTITIES));

    return strtr($str, $trans_table);

}

beer UNDRSCR nomaed AT hotmail DOT com
21-Oct-2004 04:03


Quite often, on HTML pages that are not encoded as UTF-8, and people write in not native encoding, some browser (for sure IExplorer) will send the different charset characters using HTML Entities, such as &#1073; for small russian 'b'.

htmlspecialchars() will convert this character to the entity, since it changes all & to &amp; 

What I usually do, is either turn &amp; back to & so the correct characters will appear in the output, or I use some regex to replace all entities of characters back to their original entity:

<?php

    // treat this as pseudo-code, it hasn't been tested...

    $result = preg_replace('/&amp;#(x[a-f0-9]+|[0-9]+);/i', '&#$1;', $source);

?>

Alexander Nofftz
20-Oct-2004 07:41


Why &#39;? The HTML and XML DTDs proposed &apos; for this.

See http://www.w3.org/TR/html/dtds.html#a_dtd_Special_characters



So better use this:



$text = htmlspecialchars($text, ENT_QUOTES);

$text = preg_replace('/&#0*39;/', '&apos;', $text);

mlvanbie at gmail dot com
07-Oct-2004 07:45


The code in the previous note has a bug.  If the original text was `&gt;' then htmlspecialchars will turn it into `&amp;gt;' and the suggested code will turn that into `>'.  The &amp; translation must be last.

donwilson at gmail dot com
26-Sep-2004 12:58


To reverse the action of htmlspecialchars(), use this code:



<?php

    unhtmlspecialchars( $string )

    {

        $string = str_replace ( '&amp;', '&', $string );

        $string = str_replace ( '&#039;', '\'', $string );

        $string = str_replace ( '&quot;', '\"', $string );

        $string = str_replace ( '&lt;', '<', $string );

        $string = str_replace ( '&gt;', '>', $string );

        

        return $string;

    }

?>

thelatesundayshow.com @ nathan (flip it)
03-Sep-2004 02:51


heres a version of the recursive escape function that takes the array byref rather than byval so saves some resources in case of big arrays



function recurse_array_HTML_safe(&$arr) {

    foreach ($arr as $key => $val)

        if (is_array($val))

            recurse_array_HTML_safe($arr[$key]);

        else

            $arr[$key] = htmlspecialchars($val, ENT_QUOTES);

}

moc.xnoitadnuof@310symerej
21-Apr-2004 07:04


Here are some usefull functions.

They will apply || decode, htmlspecialchars || htmlentities recursivly to arrays() || to regular $variables. They also protect agains "double encoding".



<?PHP

function htmlspecialchars_or( $mixed, $quote_style = ENT_QUOTES ){

    return is_array($mixed) ? array_map('htmlspecialchars_or',$mixed, array_fill(0,count($mixed),$quote_style)) : htmlspecialchars(htmlspecialchars_decode($mixed, $quote_style ),$quote_style);

}



function htmlspecialchars_decode( $mixed, $quote_style = ENT_QUOTES ) {

    if(is_array($mixed)){

      return array_map('htmlspecialchars_decode',$mixed, array_fill(0,count($mixed),$quote_style));

  }

  $trans_table = get_html_translation_table( HTML_SPECIALCHARS, $quote_style );

    if( $trans_table["'"] != '&#039;' ) { # some versions of PHP match single quotes to &#39;

        $trans_table["'"] = '&#039;';

    }

    return (strtr($mixed, array_flip($trans_table)));

}



function htmlentities_or($mixed, $quote_style = ENT_QUOTES){

    return is_array($mixed) ? array_map('htmlentities_or',$mixed, array_fill(0,count($mixed),$quote_style)) : htmlentities(htmlentities_decode($mixed, $quote_style ),$quote_style);

}



function htmlentities_decode( $mixed, $quote_style = ENT_QUOTES ) {

  if(is_array($mixed)){

      return array_map('htmlentities_decode',$mixed, array_fill(0,count($mixed),$quote_style));

  }

    $trans_table = get_html_translation_table(HTML_ENTITIES, $quote_style );

    if( $trans_table["'"] != '&#039;' ) { # some versions of PHP match single quotes to &#39;

        $trans_table["'"] = '&#039;';

    }

    return (strtr($mixed, array_flip($trans_table)));

}

?>



These functions are an addition to an earlier post. I would like to give the person some credit but I do not know who it was.



<?  ;llnu=u!eJq dHd?>

Dave Duchene
20-Feb-2004 09:58


Here is a handy function that will escape the contents of a variable, recursing into arrays.



<?php

function escaporize($thing) {

  if (is_array($thing)) {

    $escaped = array();

  

    foreach ($thing as $key => $value) {

      $escaped[$key] = escaporize($value);

    }

    

    return $escaped;

  }

  

  // else

  return htmlspecialchars($thing);

}

?>

mike-php at emerge2 dot com
21-Nov-2003 06:13


Here's a handy function that guards against 'double' encoding:



# Given a string, this function first strips out all html special characters, then

# encodes the string, safely returning an encoded string without double-encoding.

function get_htmlspecialchars( $given, $quote_style = ENT_QUOTES ){

   return htmlspecialchars( html_entity_decode( $given, $quote_style ), $quote_style );

}



# Needed for older versions of PHP that do not have this function built-in.

function html_entity_decode( $given_html, $quote_style = ENT_QUOTES ) {

   $trans_table = get_html_translation_table( HTML_SPECIALCHARS, $quote_style );

   if( $trans_table["'"] != '&#039;' ) { # some versions of PHP match single quotes to &#39;

      $trans_table["'"] = '&#039;';

   }

   return ( strtr( $given_html, array_flip( $trans_table ) ) );

}



Note: I set the default to ENT_QUOTES, as this makes more sense to me than the PHP function's default of ENT_COMPAT.

nospam at somewhere dot com
16-Jun-2003 01:28


most simple function for decoding html-encoded strings:





function htmldecode($encoded) {


    return strtr($encoded,array_flip(get_html_translation_table(HTML_ENTITIES)));


}

dystopia589 at yahoo dot com
13-Mar-2003 11:58


Sorry, part of that code was unnecessary. Here's a more readable version:



function SpecialChars($Security)

{

if (is_array($Security))

{

while(list($key, $val) = each($Security))

{

$Security[$key] = SpecialChars($val);

}

}

else

{

$Security = htmlspecialchars(stripslashes($Security), ENT_QUOTES);

}

return $Security;

}

webmaster at NOSPAM dot onlinegs dot com
29-Jan-2003 02:51


for those of you using V 4.3.0+ you can use html_entity_decode() to decode a string encoded with htmlspecialschars(), this should be faster and easier then using a str_replace or ereg.

_____ at luukku dot com
15-Sep-2002 05:21


People, don't use ereg_replace for the most simple string replacing operations (replacing constant string with another).

Use str_replace.

akira dot yoshi at shrine dot de
16-May-2002 12:15


If you need to htmlspecialchars a jis string, here's a function that does:



function htmlspecialchars_jis($text) {

    $ret="";

    if ($text=="") return "";

    $esc=chr(27);

    $text=$esc."$B".$esc."$B".$text;

    $text=str_replace($esc."(B", $esc."$B", $text);

    $trans=explode($esc."$B", $text);

    $enc=0;

    while (list (, $val) = each ($trans))  {

        if ($enc==0) {

            $val.="";

            if ($val!="") $ret.=htmlspecialchars($val);

            $enc=1;

        } else {

            $val.="";

            if ($val!="") $ret.=$esc."$B".$val.$esc."(B";

            $enc=0;

        };

    }

    return $ret;

};



BTW: I'm very(!) sure that JIS is iso-2022-jp, not iso-2002-jp

juadielon_NOSPAM at hotmail dot com
01-May-2002 12:09


I was trying to retrieve information from a database to display it into the browser. However it did not work as I was expecting.  For instance double quotes () and single quotes () were conflicting in HTML in an INPUT selector.





The first approach to solve this was to use htmlspecialchars to convert special characters to HTML entities to display the input box with its value.





$encode=htmlspecialchars($str, ENT_QUOTES);





However, the result was having HTML entities with a \ (backslash) preceding it (escape characters).  For instance ampersand (&) becomes \&amp; displaying \& and double quotes becomes \&quot; displaying \





So the final solution was to replace first any \ (backslash) and then ask htmlspecialchars to make the conversion.





[Editor's Note: This is the wrong way to do this. The proper way is to use 





$encoded = htmlspecialchars(stripslashes($str), ENT_QUOTES);


]





$encoded=htmlspecialchars(str_replace('\\', '', $str), ENT_QUOTES);





Try this example to see it your self.





<form action="<?php echo $PHP_SELF; ?>">


<input type="text" name="str" size="20" value="">


<input type="submit" value="Submit">


<br>


<?php


  if (!empty($str)) {


    $encoded=htmlspecialchars(str_replace('\\', '', $str), ENT_QUOTES);


    echo "<br><p>Result: <b>".$encoded."</b>. It should be the same you just typed</p>";


    echo "<p>But source code is transformed to:<b><xmp>".$encoded."</xmp></b></p>";


    // I know, I know <xmp> is deprecated in HTML 4 but was easy to use this time to display result.


  }


?>


</form>





Hope this will helps someone.

akira at kurogane dot net
02-Apr-2002 01:42


Beware of parsing JIS (aka 'iso-2002-jp') text through this function, as this function does not appear to have a sense for multibyte characters and may corrupt some characters. Eg. the japanese comma (the two ascii characters !" as viewed by an ascii client) gets transferred into !&quot; , which transforms the comma into a 'maru' mark and the following characters into garbage. 

Conceivably this could affect other multibyte charsets.

joseph at nextique dot com
20-Feb-2002 05:21


Here is a handy function to htmlalize an array (or scalar) before you hand it off to xml.



function htmlspecialchars_array($arr = array()) {

    $rs =  array();

    while(list($key,$val) = each($arr)) {

        if(is_array($val)) {

            $rs[$key] = htmlspecialchars_array($val);

        }

        else {

            $rs[$key] = htmlspecialchars($val, ENT_QUOTES);

        }    

    }

    return $rs;

}

15-Jul-2001 02:18


If your sending data from one form to another, the data in the textareas and text inputs may need to have htmlspecialchars("form data", ENT_QUOTES) applied, assuming you will ever have quotes or less-than signs or any of those special characters.  Using htmlspecialchars will make the text show up properly in the second form.  The changes are automatically undone whenever the form data is submitted. It does seem a little strange, but it works and my headache is now starting to go away.





AZ

ryan at ryano dot net
29-Jun-2001 06:06


Actually, if you're using >= 4.0.5, this should theoretically be quicker (less overhead anyway):





$text = str_replace(array("&gt;", "&lt;", "&quot;", "&amp;"), array(">", "<", "\"", "&"), $text);

david at gislaved dot net
14-Sep-2000 10:49


To replace the swedish characters...


                $s=ereg_replace(197, "&Aring;",$s);


        $s=ereg_replace(196, "&Auml;",$s);


        $s=ereg_replace(214, "&Ouml;",$s);


        $s=ereg_replace(229, "&aring;",$s);


        $s=ereg_replace(228, "&auml;",$s);


        $s=ereg_replace(246, "&ouml;",$s);

Marcel
14-Sep-2000 09:31


For HTML to text conversion see example 3 on http://www.php.net/manual/en/function.preg-replace.php

thorax at inforocket dot com
09-Dec-1999 09:26


to convert a document back from this, 


do string replacements in this order:





>   >


<   <


" "


&  &





Doing the last phase first will 


reveal erroneous results.. For example:





'<'  => specialchars() => '&lt;' '&lt;' => convert ampersands => '<' => convert everything else => '<'

add a note

htmlspecialchars

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