(PHP 4, PHP 5, PHP 7, PHP 8)

htmlspecialchars Converte i caratteri speciali in entità HTML


htmlspecialchars(string $string, int $quote_style = ?, string $charset = ?): string

Alcuni caratteri hanno significati particolari in HTML, e, per questo, devono essere rappresentati tramite entità HTML, se devono mantenere il proprio significato. Questa funzione restituisce restituisce una stringa con la conversione di alcuni di questi caratteri; la conversione svolta non è sempre valida nell'ambito della programmazione web. Se occorre l'utilizzo di tutte le entità HTML, utilizzare htmlentities().

Questa funzione è utile nel prevenire la presenza di marcatori HTML negli input utente, tipo nei forum o nei guest book. Il secondo parametro quote_style, opzionale, indica alla funzione come comportarsi con gli apici singoli e doppi. La modalità di default è, ENT_COMPAT; questa modalità è compatibile con il passato e traduce solo gli apici doppi lasciando inalterati gli apici singoli. Se si imposta ENT_QUOTES, entrambi i tipi di apici, singoli e doppi, sono convertiti in entità e, infine, se si utilizza ENT_NOQUOTES ne gli apici singoli ne gli apici doppi sono convertiti in entità.

La conversioni applicate sono:

  • '&' (e commerciale) diventa '&'
  • '"' (doppio apice) diventa '"' con ENT_NOQUOTES is not set.
  • ''' (singolo apice) diventa ''' soltanto con l'impostazione di ENT_QUOTES.
  • '<' (minore) diventa '&lt;'
  • '>' (maggiore) diventa '&gt;'

Example #1 Esempio di uso di htmlspecialchars()

htmlspecialchars("<a href='test'>Test</a>"ENT_QUOTES);
$new// &lt;a href=&#039;test&#039;&gt;Test&lt;/a&gt;

Occorre notare che questa funzione non converte null'altro oltre ai caratteri elencati in precedenza. Per la conversione di tutte le entità fare riferimento a htmlentities(). Il secondo parametro è stato inserito in PHP 3.0.17 e 4.0.3.

Il terzo parametro charset indica quale set di caratteri utilizzare nella conversione. Il set di caratteri di default è ISO-8859-1. Questo terzo parametro è stato aggiunto in PHP 4.1.0.

Elenco dei set di caratteri supportati:

Set di caratteri supportati
Set di caratteri Alias Descrizione
ISO-8859-1 ISO8859-1 Western European, Latin-1.
ISO-8859-5 ISO8859-5 Il charset cirillico poco utilizzato (Latin/Cyrillic).
ISO-8859-15 ISO8859-15 Western European, Latin-9. Con in più il simbolo dell'Euro e i caratteri francesi e finnici mancanti in Latin-1 (ISO-8859-1).
UTF-8   Set ASCII compatibile con il set multi-byte Unicode su 8-bit.
cp866 ibm866, 866 Set di caratteri cirillico specifico del Dos.
cp1251 Windows-1251, win-1251, 1251 Set di caratteri cirillico specifico di Windows.
cp1252 Windows-1252, 1252 Set di caratteri specifico di Windows per l'Europa occidentale.
KOI8-R koi8-ru, koi8r Russo.
BIG5 950 Cinese tradizionale, usato principalmente a Taiwan.
GB2312 936 Cinese semplificato, set di caratteri nazionale standard.
BIG5-HKSCS   Big5 con estensioni per Hong Kong, cinese tradizionale.
Shift_JIS SJIS, SJIS-win, cp932, 932 Giapponese.
EUC-JP EUCJP, eucJP-win Giapponese.
MacRoman   Charset che veniva utilizzato dal Mac OS.
''   Una stringa vuota attiva il rilevamento della codifica dallo script (Zend multibyte), default_charset e l'attuale locale (guarda nl_langinfo() e setlocale()), in quest'ordine. Non consigliato.

Nota: Ogni altro set di caratteri non è riconosciuto. Sarà invece utilizzata la codifica predefinita e verrà mostrato un avviso.

Vedere anche get_html_translation_table(), strip_tags(), htmlentities() e nl2br().

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User Contributed Notes 19 notes

9 years ago
As of PHP 5.4 they changed default encoding from "ISO-8859-1" to "UTF-8". So if you get null from htmlspecialchars or htmlentities

where you have only set
echo htmlspecialchars($string);

you can fix it by
echo htmlspecialchars($string, ENT_COMPAT,'ISO-8859-1', true);
htmlentities($string, ENT_COMPAT,'ISO-8859-1', true);

On linux you can find the scripts you need to fix by

grep -Rl "htmlspecialchars\\|htmlentities" /path/to/php/scripts/
Mike Robinson
9 years ago
Unfortunately, as far as I can tell, the PHP devs did not provide ANY way to set the default encoding used by htmlspecialchars() or htmlentities(), even though they changed the default encoding in PHP 5.4 (*golf clap for PHP devs*). To save someone the time of trying it, this does not work:

('default_charset', $charset); // doesn't work.

Unfortunately, the only way to not have to explicitly provide the second and third parameter every single time this function is called (which gets extremely tedious) is to write your own function as a wrapper:

('CHARSET', 'ISO-8859-1');

html($string) {
htmlspecialchars($string, REPLACE_FLAGS, CHARSET);

html("ñ"); // works

You can do the same for htmlentities()
Thomasvdbulk at gmail dot com
11 years ago
i searched for a while for a script, that could see the difference between an html tag and just < and > placed in the text,
the reason is that i recieve text from a database,
wich is inserted by an html form, and contains text and html tags,
the text can contain < and >, so does the tags,
with htmlspecialchars you can validate your text to XHTML,
but you'll also change the tags, like <b> to &lt;b&gt;,
so i needed a script that could see the difference between those two...
but i couldn't find one so i made my own one,
i havent fully tested it, but the parts i tested worked perfect!
just for people that were searching for something like this,
it may looks big, could be done easier, but it works for me, so im happy.

function fixtags($text){
$text = htmlspecialchars($text);
$text = preg_replace("/=/", "=\"\"", $text);
$text = preg_replace("/&quot;/", "&quot;\"", $text);
$tags = "/&lt;(\/|)(\w*)(\ |)(\w*)([\\\=]*)(?|(\")\"&quot;\"|)(?|(.*)?&quot;(\")|)([\ ]?)(\/|)&gt;/i";
$replacement = "<$1$2$3$4$5$6$7$8$9$10>";
$text = preg_replace($tags, $replacement, $text);
$text = preg_replace("/=\"\"/", "=", $text);

an example:

= "
this is smaller < than this<br />
this is greater > than this<br />
this is the same = as this<br />
<a href=\"\">This is a link</a><br />
<b>Bold</b> <i>italic</i> etc..."

will echo:
this is smaller &lt; than this<br />
this is greater &gt; than this<br />
this is the same = as this<br />
<a href="">This is a link</a><br />
<b>Bold</b> <i>italic</i> etc...

I hope its helpfull!!
Kenneth Kin Lum
13 years ago
if your goal is just to protect your page from Cross Site Scripting (XSS) attack, or just to show HTML tags on a web page (showing <body> on the page, for example), then using htmlspecialchars() is good enough and better than using htmlentities().  A minor point is htmlspecialchars() is faster than htmlentities().  A more important point is, when we use  htmlspecialchars($s) in our code, it is automatically compatible with UTF-8 string.  Otherwise, if we use htmlentities($s), and there happens to be foreign characters in the string $s in UTF-8 encoding, then htmlentities() is going to mess it up, as it modifies the byte 0x80 to 0xFF in the string to entities like &eacute;.  (unless you specifically provide a second argument and a third argument to htmlentities(), with the third argument being "UTF-8").

The reason htmlspecialchars($s) already works with UTF-8 string is that, it changes bytes that are in the range 0x00 to 0x7F to &lt; etc, while leaving bytes in the range 0x80 to 0xFF unchanged.  We may wonder whether htmlspecialchars() may accidentally change any byte in a 2 to 4 byte UTF-8 character to &lt; etc.  The answer is, it won't.  When a UTF-8 character is 2 to 4 bytes long, all the bytes in this character is in the 0x80 to 0xFF range. None can be in the 0x00 to 0x7F range.  When a UTF-8 character is 1 byte long, it is just the same as ASCII, which is 7 bit, from 0x00 to 0x7F.  As a result, when a UTF-8 character is 1 byte long, htmlspecialchars($s) will do its job, and when the UTF-8 character is 2 to 4 bytes long, htmlspecialchars($s) will just pass those bytes unchanged.  So htmlspecialchars($s) will do the same job no matter whether $s is in ASCII, ISO-8859-1 (Latin-1), or UTF-8.
Felix D.
8 years ago
Another thing important to mention is that
returnes an empty string and not NULL!
ivan at lutrov dot com
11 years ago
Be careful, the "charset" argument IS case sensitive. This is counter-intuitive and serves no practical purpose because the HTML spec actually has the opposite.
ryan at ryano dot net
21 years ago
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);
13 years ago
This may seem obvious, but it caused me some frustration. If you try and use htmlspecialchars with the $charset argument set and the string you run it on is not actually the same charset you specify, you get any empty string returned without any notice/warning/error.


= "A valid UTF-8 string";
$bad_utf8 = "An invalid UTF-8 string";

var_dump(htmlspecialchars($bad_utf8, ENT_NOQUOTES, 'UTF-8'));  // string(0) ""

var_dump(htmlspecialchars($ok_utf8, ENT_NOQUOTES, 'UTF-8'));  // string(20) "A valid UTF-8 string"


So make sure your charsets are consistent


= "An invalid UTF-8 string";

// make sure it's really UTF-8
$bad_utf8 = mb_convert_encoding($bad_utf8, 'UTF-8', mb_detect_encoding($bad_utf8));

var_dump(htmlspecialchars($bad_utf8, ENT_NOQUOTES, 'UTF-8'));  // string(23) "An invalid UTF-8 string"


I had this problem because a Mac user was submitting posts copy/pasted from a program and it contained weird chars in it.
13 years ago
Just a few notes on how one can use htmlspecialchars() and htmlentities() to filter user input on forms for later display and/or database storage...

1. Use htmlspecialchars() to filter text input values for html input tags.  i.e.,

echo '<input name=userdata type=text value="'.htmlspecialchars($data).'" />';

2. Use htmlentities() to filter the same data values for most other kinds of html tags, i.e.,

echo '<p>'.htmlentities($data).'</p>';

3. Use your database escape string function to filter the data for database updates & insertions, for instance, using postgresql,

pg_query($connection,"UPDATE datatable SET datavalue='".pg_escape_string($data)."'");

This strategy seems to work well and consistently, without restricting anything the user might like to type and display, while still providing a good deal of protection against a wide variety of html and database escape sequence injections, which might otherwise be introduced through deliberate and/or accidental input of such character sequences by users submitting their input data via html forms.
php dot net at orakio dot net
14 years ago
I was recently exploring some code when I saw this being used to make data safe for "SQL".

This function should not be used to make data SQL safe (although to prevent phishing it is perfectly good).

Here is an example of how NOT to use this function:

= htmlspecialchars(trim("$_POST[username]"));

$uniqueuser = $realm_db->query("SELECT `login` FROM `accounts` WHERE `login` = '$username'");

(Only other check on $_POST['username'] is to make sure it isn't empty which it is after trim on a white space only name)

The problem here is that it is left to default which allows single quote marks which are used in the sql query. Turning on magic quotes might fix it but you should not rely on magic quotes, in fact you should never use it and fix the code instead. There are also problems with \ not being escaped. Even if magic quotes were used there would be the problem of allowing usernames longer than the limit and having some really weird usernames given they are to be used outside of html, this just provide a front end for registering to another system using mysql. Of course using it on the output wouldn;t cause that problem.

Another way to make something of a fix would be to use ENT_QUOTE or do:

= $realm_db->query('SELECT `login` FROM `accounts` WHERE `login` = "'.$username.'";');

Eitherway none of these solutions are good practice and are not entirely unflawed. This function should simply never be used in such a fashion.

I hope this will prevent newbies using this function incorrectly (as they apparently do).
7 years ago
Be aware of the encoding of your source files!!!

Some of the suggestions here make reference to workarounds where you hard-code an encoding.

echo htmlspecialchars('<b>Wörmann</b>');  // Why isn't this working?

As it turns out, it may actually be your text editor that is to blame.

As of PHP 5.4, htmlspecialchars now defaults to the UTF-8 encoding. That said, many text editors default to non-UTF encodings like ISO-8859-1 (i.e. Latin-1) or WIN-1252. If you change the encoding of the file to UTF-8, the code above will now work (i.e. the ö is encoded differently in UTF-8 and ISO-8859-1, and you need the UTF-8 version).

Make sure you are editing in UTF-8 Unicode mode! Check your UI or manual for how to convert files to Unicode. It's also a good idea to figure out where to look in your UI to see what the current file encoding is.
minder at ufive dot unibe dot ch
9 years ago

In many PHP legacy products the function htmlspecialchars($string) is used to convert characters like < and > and quotes a.s.o to HTML-entities. That avoids the interpretation of HTML Tags and asymmetric quote situations.

Since PHP 5.4 for $string in htmlspecialchars($string) utf8 characters are expected if no charset is defined explicitly as third parameter in the function. Legacy products are mostly in Latin1 (alias iso-8859-1) what makes the functions htmlspecialchars(), htmlentites() and html_entity_decode() to return empty strings if a special character, e. g. a German Umlaut, is present in $string:


echo htmlspecialchars('<b>Woermann</b>') //Output: &lt;b&gt;Woermann&lt;b&gt;
echo htmlspecialchars('Wörmann') //Output: &lt;b&gt;Wörmann&lt;b&gt;


echo htmlspecialchars('<b>Woermann</b>') //Output: &lt;b&gt;Woermann&lt;b&gt;
echo htmlspecialchars('<b>Wörmann</b>') //Output: empty

Three alternative solutions

a) Not runnig legacy products on PHP 5.4
b) Change all find spots in your code from
htmlspecialchars($string) and *** to
htmlspecialchars($string, ENT_COMPAT | ENT_HTML401, 'ISO-8859-1')
c) Replace all htmlspecialchars() and *** with a new self-made function

*** The same is true for htmlentities() and html_entity_decode();

Solution c

1 Make Search and Replace in the concerned legacy project:
Search for:        htmlspecialchars
Replace with:   htmlXspecialchars
Search for:        htmlentities
Replace with:   htmlXentities
Search for:        html_entity_decode
Replace with:   htmlX_entity_decode
2a Copy and paste the following three functions into an existing already everywhere included PHP-file in your legacy project. (of course that PHP-file must be included only once per request, otherwise you will get a Redeclare Function Fatal Error).

function htmlXspecialchars($string, $ent=ENT_COMPAT, $charset='ISO-8859-1') {
return htmlspecialchars($string, $ent, $charset);

function htmlXentities($string, $ent=ENT_COMPAT, $charset='ISO-8859-1') {
return htmlentities($string, $ent, $charset);

function htmlX_entity_decode($string, $ent=ENT_COMPAT, $charset='ISO-8859-1') {
return html_entity_decode($string, $ent, $charset);

or 2b crate a new PHP-file containing the three functions mentioned above, let's say, z. B. and include it on the first line of every PHP-file in your legacy product like this: require_once('').
15 years ago
also see function "urlencode()", useful for passing text with ampersand and other special chars through url

(i.e. the text is encoded as if sent from form using GET method)


echo "<a href='foo.php?text=".urlencode("foo?&bar!")."'>link</a>";


<a href='foo.php?text=foo%3F%26bar%21'>link</a>

and if the link is followed, the $_GET["text"] in foo.php will contain "foo?&bar!"
ASchmidt at Anamera dot net
1 year ago
One MUST specify ENT_HTML5 in addition to double_encode=false to avoid double-encoding.

The reason is that contrary to the documentation, double_encode=false will NOT unconditionally and globally prevent double-encoding of ALL existing entities. Crucially, it will only skip double-encoding for THOSE character entities that are explicitly valid for the document type chosen!

Since ENT_HTML5 references the most expansive list of character entities, it is the only setting that will be most lenient with existing character entities.

$text = 'ampersand(&amp;), double quote(&quot;), single quote(&apos;), less than(&lt;), greater than(&gt;), numeric entities(&#x26;&#x22;&#x27;&#x3C;&#x3E;), HTML 5 entities(&plus;&comma;&excl;&dollar;&lpar;&ncedil;&euro;)';
$result3 = htmlspecialchars( $text, ENT_NOQUOTES | ENT_SUBSTITUTE, 'UTF-8', /*double_encode*/false );
$result4 = htmlspecialchars( $text, ENT_NOQUOTES | ENT_XML1 | ENT_SUBSTITUTE, 'UTF-8', /*double_encode*/false );
$result5 = htmlspecialchars( $text, ENT_NOQUOTES | ENT_XHTML | ENT_SUBSTITUTE, 'UTF-8', /*double_encode*/false );
$result6 = htmlspecialchars( $text, ENT_NOQUOTES | ENT_HTML5 | ENT_SUBSTITUTE, 'UTF-8', /*double_encode*/false );

"<br />\r\nHTML 4.01:<br />\r\n", $result3,
"<br />\r\nXML 1:<br />\r\n", $result4,
"<br />\r\nXHTML:<br />\r\n", $result5,
"<br />\r\nHTML 5:<br />\r\n", $result6, "<br />\r\n";

will produce:

HTML 4.01 (will NOT recognize single quote, but Euro):
ampersand(&), double quote("), single quote(&apos;), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(&plus;&comma;&excl;&dollar;&lpar;&ncedil;€)

XML 1 (WILL recognize single quote, but NOT Euro):
ampersand(&), double quote("), single quote('), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(&plus;&comma;&excl;&dollar;&lpar;&ncedil;&euro;)

XHTML (recognizes single quote and Euro):
ampersand(&), double quote("), single quote('), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(&plus;&comma;&excl;&dollar;&lpar;&ncedil;€)

HTML 5 (recognizes "all" valid character entities):
ampersand(&), double quote("), single quote('), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(+,!$(ņ€)
_____ at luukku dot com
20 years ago
People, don't use ereg_replace for the most simple string replacing operations (replacing constant string with another).
Use str_replace.
support at playnext dot ru
8 years ago
For those having problems after the change of default value of $encoding argument to UTF-8 since PHP 5.4.

If your old non-UTF8 projects ruined - pls consider:

The idea - you override the built-in htmlspecialchars() function with your customized variant which is able to respect non UTF-8 default encoding. This small piece of code can be then easily inserted somewhere at the start of yout project. No need to rewrite all htmlspecialchars() entries globally.

I've spent several hours with both approaches. Variant 1 looks good especaially in combination with as it allows to call original htmlspecialchars() with just altered default args. The code could be as follows:

('htmlspecialchars', 'renamed_htmlspecialchars');
overriden_htmlspecialchars($string, $flags=NULL, $encoding='cp1251', $double_encode=true) {
$flags = $flags ? $flags : (ENT_COMPAT|ENT_HTML401);
renamed_htmlspecialchars($string, $flags, $encoding, $double_encode);
override_function('htmlspecialchars', '$string, $flags, $encoding, $double_encode', 'return overriden_htmlspecialchars($string, $flags, $encoding, $double_encode);');

Unfortunatelly this didn't work for me properly - my site managed to call overriden function but not every time I reloaded the pages. Moreover other PHP sites crashed under my Apache server as they suddenly started blaming htmlspecialchars() was not defined. I suppose I had to spend more time to make it work thread/request/site/whatever-safe.

So I switched to runkit (variant 2). It worked for me, although even after trying runkit_function_rename()+runkit_function_add() I didn't managed to recall original htmlspecialchars() function. So as a quick solution I decided to call htmlentities() instead:

function overriden_htmlspecialchars($string, $flags=NULL, $encoding='UTF-8', $double_encode=true) {
$flags = $flags ? $flags : (ENT_COMPAT|ENT_HTML401);
$encoding = $encoding ? $encoding : 'cp1251';
htmlentities($string, $flags, $encoding, $double_encode);
runkit_function_redefine('htmlspecialchars', '$string, $flags, $encoding, $double_encode', 'return overriden_htmlspecialchars($string, $flags, $encoding, $double_encode);');

You may be able to implement your more powerfull overriden function.
Good luck!
nachitox2000 [at] hotmail [dot] com
12 years ago
I had problems with spanish special characters. So i think in using htmlspecialchars but my strings also contain HTML.
So I used this :) Hope it help

function htmlspanishchars($str)
str_replace(array("&lt;", "&gt;"), array("<", ">"), htmlspecialchars($str, ENT_NOQUOTES, "UTF-8"));
17 years ago
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;
qshing1437 at hotmail dot com
3 years ago
If you use htmlspecialchars() to escape any HTML attribute, make sure use double quote instead of single quote for the attribute.

For Example,

> Wrap with Single Quote
echo "<p title='"  . htmlspecialchars("Hello\"s\'world") . "'">

// title will end up Hello"s\ and rest of the text after single quote will be cut off.

> Wrap with Double quote :
echo '<p title="'  . htmlspecialchars("Hello\"s\'world") . '"'>

// title will show up correctly as Hello"s'world
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