Dutch PHP Conference 2021 - Call for Papers


(PHP 4, PHP 5, PHP 7)

htmlspecialchars Converte caracteres especiais para a realidade HTML


htmlspecialchars ( string $string [, int $quote_style [, string $charset ]] ) : string

Certos caracteres tem significado especial em HTML, e seriam representados pela realidade HTML se eles estão preservanado seus significados. Esta função retorna uma string com algumas destas conversões feitas; As transformações feitas são aquelas mais úteis para programação web. Se você precisa que sejam transformados todos os caracteres da realidade HTML, use htmlentities() no lugar dela.

Esta função é útil na prevenção de textos fornecidos pelo usuário contendo marcação HTML, tal como um quadro de mensgens ou guest book. O segundo argumento opcional, quote_style, conta à função o que fazer com os caracteres aspas simples e dupla. O modo padrão, ENT_COMPAT, é o modo mais compatível com a atualidade, apenas transforma a aspas-dupla e deixa a aspas-simples como está. Se ENT_QUOTES está definida, ambas transformadas e se ENT_NOQUOTES está definida nenhuma das duas são modificadas.

As traduções executadas são:

  • '&' (ampersand) torna-se '&'
  • '"' (aspas dupla) torna-se '"' quando ENT_NOQUOTES não está definida.
  • ''' (aspas simples) torna-se ''' apenas quando ENT_QUOTES está definida.
  • '<' (menor que) torna-se '&lt;'
  • '>' (maior que) torna-se '&gt;'

Exemplo #1 htmlspecialchars() exemplo

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

Note que esta função não converte nada além do que foi listado acima. Para completa realidade de conversões, veja htmlentities(). Suporte para o segundo argumento opcional foi adicionado no PHP 3.0.17 e PHP 4.0.3.

O terceiro argumento define o conjunto de caracteres usados na conversão. O conjunto de caracteres padrão é ISO-8859-1. Suporte para o terceiro argumento foi adicionado no PHP 4.1.0.

Os seguintes conjuntos de caracteres são suportados no PHP 4.3.0 e posterior.

Conjuntos de caracteres suportados
Conjunto de caracteres Apelidos Descrição
ISO-8859-1 ISO8859-1 Western European, Latin-1
ISO-8859-15 ISO8859-15 Western European, Latin-9. Adiciona o símbolo do Euro, letras Francesas e Filandesas faltando no Latin-1(ISO-8859-1).
UTF-8   Código de multi-byte 8-bit Unicode compatível com ASCII.
cp866 ibm866, 866 Conjunto de caracteres do DOS específico para o Russo. Este conjunto de caracteres é suportado no 4.3.2.
cp1251 Windows-1251, win-1251, 1251 Conjunto de caracteres do Windows específico para o Russo. Este conjunto de caracteres é suportado no 4.3.2.
cp1252 Windows-1252, 1252 Conjunto de caracteres do Windows específico para a Europa Ocidental.
KOI8-R koi8-ru, koi8r Russo. Este conjunto de caracteres é suportado no 4.3.2.
BIG5 950 Chinês Tradicional, usado principalmente em Taiwan.
GB2312 936 Chins Simplificado, conjunto de caracteres padrão nacional.
BIG5-HKSCS   Big5 com extenções de Hong Kong, Chinês Tradicional.
Shift_JIS SJIS, 932 Japonês

Nota: Qualquer outro conjunto de caracteres não é reconhecido e será usado o ISO-8859-1.

Veja também get_html_translation_table(), htmlentities(), strip_tags() e nl2br().

add a note add a note

User Contributed Notes 18 notes

7 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
7 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
10 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=\"http://www.example.com/example.php?test=test\">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="http://www.example.com/example.php?test=test">This is a link</a><br />
<b>Bold</b> <i>italic</i> etc...

I hope its helpfull!!
Felix D.
7 years ago
Another thing important to mention is that
returnes an empty string and not NULL!
Kenneth Kin Lum
12 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.
ivan at lutrov dot com
9 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
19 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);
11 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.
11 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
12 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).
minder at ufive dot unibe dot ch
7 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. htmlXfunctions.inc.php and include it on the first line of every PHP-file in your legacy product like this: require_once('htmlXfunctions.inc.php').
13 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!"
5 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.
qshing1437 at hotmail dot com
1 year 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
_____ at luukku dot com
18 years ago
People, don't use ereg_replace for the most simple string replacing operations (replacing constant string with another).
Use str_replace.
15 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;
support at playnext dot ru
7 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:
1. http://php.net/manual/en/function.override-function.php
2. http://php.net/manual/ru/function.runkit-function-redefine.php

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 http://www.php.net/manual/en/function.rename-function.php 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
10 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"));
To Top