htmlspecialchars

(PHP 4, PHP 5, PHP 7)

htmlspecialchars특수 문자를 HTML 엔터티로 변환

설명

string htmlspecialchars ( string $string [, int $quote_style [, string $charset [, bool $double_encode ]]] )

어떤 문자들은 HTML에서 특별한 정의를 가지기에, 그 의미를 보존하려면, HTML 엔터티로 표현해야 합니다. 이 함수는 이러한 변환을 수행한 문자열을 반환합니다; 이 번역은 모든 웹 프로그래밍에서 매우 유용합니다. 모든 HTML 문자 엔터티를 번역해야 한다면, 이 함수 대신 htmlentities()를 사용하십시오.

이 함수로 게시판이나 방명록 등의 프로그램에서, HTML을 포함하는 사용자 입력 텍스트를 막을 수 있습니다.

변환이 일어나는 문자는:

  • '&'(앰퍼샌드)는 '&'가 됩니다
  • '"'(겹따옴표)는 ENT_NOQUOTES를 설정하지 않았을 때 '"'가 됩니다.
  • '''(홑따옴표)는 ENT_QUOTES가 설정되었을 때만 '''가 됩니다.
  • '<'(미만)은 '&lt;'가 됩니다.
  • '>'(이상)은 '&gt;'가 됩니다.

인수

string

변환할 string.

quote_style

선택적인 두번째 인수 quote_style은 홑따옴표와 겹따옴표를 어떻게 처리할지 결정합니다. 기본 모드는 하위 호환 모드 ENT_COMPAT로, 겹따옴표만 변환합니다. ENT_QUOTES를 지정하면 홑따옴표와 겹따옴표 둘 다 변환하고, ENT_NOQUOTES를 지정하면 홑따옴표와 큰 따옴표 둘 다 변환하지 않습니다.

charset

변환에 사용할 문자셋을 정의합니다. 기본 문자셋은 ISO-8859-1입니다.

PHP 4.3.0 이상에서 다음 문자셋을 지원합니다.

지원 문자셋
문자셋 다른 이름 설명
ISO-8859-1 ISO8859-1 서부 유럽어, Latin-1.
ISO-8859-15 ISO8859-15 서부 유럽어, Latin-9. 유로 사인, Latin-1(ISO-8859-1)에 빠진 프랑스어와 핀란드어 문자 추가.
UTF-8   아스키 호환 멀티바이트 8비트 유니코드.
cp866 ibm866, 866 DOS-특정 키릴 문자셋. 이 문자셋은 4.3.2부터 지원합니다.
cp1251 Windows-1251, win-1251, 1251 윈도우-특정 키릴 문자셋. 이 문자셋은 4.3.2부터 지원합니다.
cp1252 Windows-1252, 1252 윈도우 특정 서부 유럽어 문자셋
KOI8-R koi8-ru, koi8r 러시아어. 이 문자셋은 4.3.2부터 지원합니다.
BIG5 950 중국어 번체, 주로 대만에서 사용.
GB2312 936 중국어 간체, 국가 표준 문자셋.
BIG5-HKSCS   홍콩 확장을 포함한 Big5, 중국어 번체.
Shift_JIS SJIS, 932 일본어.
EUC-JP EUCJP 일본어.

Note: 다른 문자셋에 대해서는 ISO-8859-1을 사용합니다.

double_encode

double_encode를 끄면 PHP는 이미 존재하는 html 엔티티를 인코드하지 않습니다. 기본값은 모두 변환합니다.

반환값

변환된 string.

변경점

버전 설명
5.2.3 double_encode 인수 추가.
4.1.0 charset 인수 추가.

예제

Example #1 htmlspecialchars() 예제

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

주의

Note:

이 함수는 위 목록 이외에는 아무 것도 번역하지 않는 점에 주의하십시오. 완전한 엔터티 번역을 위해서는, htmlentities()를 참고하십시오.

참고

add a note add a note

User Contributed Notes 19 notes

up
74
Dave
8 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
<?php
echo htmlspecialchars($string);
echo
htmlentities($string);
?>

you can fix it by
<?php
echo htmlspecialchars($string, ENT_COMPAT,'ISO-8859-1', true);
echo
htmlentities($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/
up
48
Mike Robinson
8 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:

<?php
ini_set
('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:

<?php
define
('CHARSET', 'ISO-8859-1');
define('REPLACE_FLAGS', ENT_COMPAT | ENT_XHTML);

function
html($string) {
    return
htmlspecialchars($string, REPLACE_FLAGS, CHARSET);
}

echo
html("ñ"); // works
?>

You can do the same for htmlentities()
up
25
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.

<?php
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);
return
$text;
}
?>

an example:

<?php
$string
= "
this is smaller < than this<br />
this is greater > than this<br />
this is the same = as this<br />
<a href=\"http://www.example.com/example.php?test=test\">This is a link</a><br />
<b>Bold</b> <i>italic</i> etc..."
;
echo
fixtags($string);
?>

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!!
up
11
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.
up
8
Felix D.
7 years ago
Another thing important to mention is that
htmlspecialchars(NULL)
returnes an empty string and not NULL!
up
12
ivan at lutrov dot com
10 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.
up
7
ryan at ryano dot net
20 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);
up
5
Anonymous
12 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.

<?php

$ok_utf8
= "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

<?php

$bad_utf8
= "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.
up
6
Anonymous
12 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.
up
4
php dot net at orakio dot net
13 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:

<?php
$username
= htmlspecialchars(trim("$_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:

<?php
$uniqueuser
= $realm_db->query('SELECT `login` FROM `accounts` WHERE `login` = "'.$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).
up
4
PoV
6 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.

<?php
 
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.
up
4
minder at ufive dot unibe dot ch
8 years ago
Problem

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:

PHP<5.4

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

PHP=5.4

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').
up
3
solar-energy
14 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)

e.g.

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

produces

<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!"
up
0
ASchmidt at Anamera dot net
7 months 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.

<?php
declare(strict_types=1);
$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 );

echo
"<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€)
up
0
_____ at luukku dot com
19 years ago
People, don't use ereg_replace for the most simple string replacing operations (replacing constant string with another).
Use str_replace.
up
-1
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:
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:

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

<?php
function overriden_htmlspecialchars($string, $flags=NULL, $encoding='UTF-8', $double_encode=true) {
   
$flags = $flags ? $flags : (ENT_COMPAT|ENT_HTML401);
   
$encoding = $encoding ? $encoding : 'cp1251';
    return
htmlentities($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!
up
-1
nachitox2000 [at] hotmail [dot] com
11 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

<?php
function htmlspanishchars($str)
{
    return
str_replace(array("&lt;", "&gt;"), array("<", ">"), htmlspecialchars($str, ENT_NOQUOTES, "UTF-8"));
}
?>
up
-1
Anonymous
16 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;
}
up
-1
qshing1437 at hotmail dot com
2 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
<?php
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 :
<?php
echo '<p title="'  . htmlspecialchars("Hello\"s\'world") . '"'>

// title will show up correctly as Hello"s'world
?>
To Top