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htmlspecialchars
(
string
$string
,
int
$flags
= ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401
,
?
string
$encoding
=
null
,
bool
$double_encode
=
true
):
string
某类字符在 HTML 中有特殊用处，如需保持原意，需要用 HTML 实体来表达。
本函数会返回字符转义后的表达。
如需转换子字符串中所有关联的名称实体，使用
htmlentities()
代替本函数。
如果传入字符的字符编码和最终的文档是一致的，则用函数处理的输入适合绝大多数 HTML 文档环境。
然而，如果输入的字符编码和最终包含字符的文档是不一样的，
想要保留字符（以数字或名称实体的形式），本函数以及
htmlentities()
（仅编码名称实体对应的子字符串）可能不够用。
这种情况可以使用
mb_encode_numericentity()
代替。
为文档的无效代码点替换为 Unicode 代替符（Replacement Character）：
U+FFFD (UTF-8)，或 �（其他），而不是把它们留在原处。
比如以下情况下就很有用：要保证 XML 文档嵌入额外内容时格式合法。
Although this argument is technically optional, you are highly encouraged to
specify the correct value for your code
if the
default_charset
configuration option may be set incorrectly for the given input.
本函数使用效果上，如果
string
对以下字符编码是有效的，
ISO-8859-1
、
ISO-8859-15
、
UTF-8
、
cp866
、
cp1251
、
cp1252
、
KOI8-R
将具有相同的效果。
也就是说，在这些编码里，
受
htmlspecialchars()
影响的字符会占据相同的位置。
An empty string activates detection from script encoding (Zend multibyte),
default_charset
and current
locale (see
nl_langinfo()
and
setlocale()
), in this order. Not recommended.
get_html_translation_table()
- 返回使用 htmlspecialchars 和 htmlentities 后的转换表
htmlspecialchars_decode()
- 将特殊的 HTML 实体转换回普通字符
strip_tags()
- 从字符串中去除 HTML 和 PHP 标签
htmlentities()
- 将字符转换为 HTML 转义字符
nl2br()
- 在字符串所有新行之前插入 HTML 换行标记
Dave
¶
12 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/
Mike Robinson
¶
12 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
);
?>
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
(
$string
,
REPLACE_FLAGS
,
CHARSET
);
}
echo
html
(
"ñ"
);
?>
You can do the same for htmlentities()
Kenneth Kin Lum
¶
16 years ago
if your goal is just to protect your page from Cross Site Scripting (XSS) attack, or just to show HTML tags on a web page (showing <body> on the page, for example), then using htmlspecialchars() is good enough and better than using htmlentities(). A minor point is htmlspecialchars() is faster than htmlentities(). A more important point is, when we use htmlspecialchars($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 $s in UTF-8 encoding, then htmlentities() is going to mess it up, as it modifies the byte 0x80 to 0xFF in the string to entities like é. (unless you specifically provide a second argument and a third argument to htmlentities(), with the third argument being "UTF-8").
The reason htmlspecialchars($s) already works with UTF-8 string is that, it changes bytes that are in the range 0x00 to 0x7F to < 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 < 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.
Thomasvdbulk at gmail dot com
¶
14 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 <b>,
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
(
"/"/"
,
""\""
,
$text
);
$tags
=
"/<(\/|)(\w*)(\ |)(\w*)([\\\=]*)(?|(\")\""\"|)(?|(.*)?"(\")|)([\ ]?)(\/|)>/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 < 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...
I hope its helpfull!!
Daniel Klein
¶
3 years ago
Because the documentation says
int $flags = ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401
you would think that ENT_HTML401 is important. But as the notes mention, ENT_HTML401 is the default if you don't specify the doc type. This is because ENT_HTML401 === 0. So
int $flags = ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401
is exactly equivalent to
int $flags = ENT_QUOTES | ENT_SUBSTITUTE
qshing1437 at hotmail dot com
¶
6 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"
) .
"'"
>
?>
> Wrap with Double quote :
<?php
echo
'<p title="'
.
htmlspecialchars
(
"Hello\"s\'world"
) .
'"'
>
?>
ASchmidt at Anamera dot net
¶
4 years 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
);
$text
=
'ampersand(&), double quote("), single quote('), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(+,!$(ņ€)'
;
$result3
=
htmlspecialchars
(
$text
,
ENT_NOQUOTES
|
ENT_SUBSTITUTE
,
'UTF-8'
,
false
);
$result4
=
htmlspecialchars
(
$text
,
ENT_NOQUOTES
|
ENT_XML1
|
ENT_SUBSTITUTE
,
'UTF-8'
,
false
);
$result5
=
htmlspecialchars
(
$text
,
ENT_NOQUOTES
|
ENT_XHTML
|
ENT_SUBSTITUTE
,
'UTF-8'
,
false
);
$result6
=
htmlspecialchars
(
$text
,
ENT_NOQUOTES
|
ENT_HTML5
|
ENT_SUBSTITUTE
,
'UTF-8'
,
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"
,
$result6
,
"<br />\r\n"
;
?>
will produce:
HTML 4.01 (will NOT recognize single quote, but Euro):
ampersand(&), double quote("), single quote('), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(+,!$(ņ€)
XML 1 (WILL recognize single quote, but NOT Euro):
ampersand(&), double quote("), single quote('), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(+,!$(ņ€)
XHTML (recognizes single quote and Euro):
ampersand(&), double quote("), single quote('), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(+,!$(ņ€)
HTML 5 (recognizes "all" valid character entities):
ampersand(&), double quote("), single quote('), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(+,!$(ņ€)
Anonymous
¶
15 years ago
Just a few notes on how one can use htmlspecialchars() and htmlentities() to filter user input on forms for later display and/or database storage...
1. Use htmlspecialchars() to filter text input values for html input tags. i.e.,
echo '<input name=userdata type=text value="'.htmlspecialchars($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.
Anonymous
¶
15 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'
));
var_dump
(
htmlspecialchars
(
$ok_utf8
,
ENT_NOQUOTES
,
'UTF-8'
));
?>
So make sure your charsets are consistent
<?php
$bad_utf8
=
"An invalid UTF-8 string"
;
$bad_utf8
=
mb_convert_encoding
(
$bad_utf8
,
'UTF-8'
,
mb_detect_encoding
(
$bad_utf8
));
var_dump
(
htmlspecialchars
(
$bad_utf8
,
ENT_NOQUOTES
,
'UTF-8'
));
?>
I had this problem because a Mac user was submitting posts copy/pasted from a program and it contained weird chars in it.
php dot net at orakio dot net
¶
17 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` = "'
.
$username
.
'";'
);
?>
Eitherway none of these solutions are good practice and are not entirely unflawed. This function should simply never be used in such a fashion.
I hope this will prevent newbies using this function incorrectly (as they apparently do).
PoV
¶
10 years ago
Be aware of the encoding of your source files!!!
Some of the suggestions here make reference to workarounds where you hard-code an encoding.
<?php
echo
htmlspecialchars
(
'<b>Wörmann</b>'
);
?>
As it turns out, it may actually be your text editor that is to blame.
As of PHP 5.4, htmlspecialchars now defaults to the UTF-8 encoding. That said, many text editors default to non-UTF encodings like ISO-8859-1 (i.e. Latin-1) or WIN-1252. If you change the encoding of the file to UTF-8, the code above will now work (i.e. the ö is encoded differently in UTF-8 and ISO-8859-1, and you need the UTF-8 version).
Make sure you are editing in UTF-8 Unicode mode! Check your UI or manual for how to convert files to Unicode. It's also a good idea to figure out where to look in your UI to see what the current file encoding is.
minder at ufive dot unibe dot ch
¶
12 years ago
Problem
In many PHP legacy products the function htmlspecialchars($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 $string:
PHP<5.4
echo htmlspecialchars('<b>Woermann</b>') //Output: <b>Woermann<b>
echo htmlspecialchars('Wörmann') //Output: <b>Wörmann<b>
PHP=5.4
echo htmlspecialchars('<b>Woermann</b>') //Output: <b>Woermann<b>
echo htmlspecialchars('<b>Wörmann</b>') //Output: empty
Three alternative solutions
a) Not runnig legacy products on PHP 5.4
b) Change all find spots in your code from
htmlspecialchars($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').
nachitox2000 [at] hotmail [dot] com
¶
15 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(
"<"
,
">"
), array(
"<"
,
">"
),
htmlspecialchars
(
$str
,
ENT_NOQUOTES
,
"UTF-8"
));
}
?>
Killian Leroux
¶
3 years ago
Thanks Thomasvdbulk for your workaround, I would like to add a precision:
When the HTML contains a link tag without new line before the script doesn't work :/
Your 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
);
?>
Works but this doesn't work:
<?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
);
?>
So I add a little workaround at the beginning (before htmlspecialchars):
<?php
$text
=
preg_replace
(
'/<a/'
,
"\r\n<a"
,
$text
);
?>
I don't like that but I don't find other solution... :/
solar-energy
¶
18 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!"
