(PHP 4, PHP 5, PHP 7, PHP 8)
htmlspecialchars — Wandelt Sonderzeichen in HTML-Entities um
$string,$flags = ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401,$encoding = null,$double_encode = trueBestimmte Zeichen haben in HTML eine spezielle Bedeutung und sollten in HTML-Entities dargestellt werden, um ihre Bedeutung zu behalten. Diese Funktion gibt eine Zeichenkette zurück, in der diese Umwandlungen durchgeführt wurden. Ist es erforderlich, dass alle Teilzeichenketten der Eingabe, die zugeordnete benannte Entities haben, übersetzt werden, sollte stattdessen htmlentities() verwendet werden.
Wenn die Eingabezeichenkette, die dieser Funktion übergeben wird, und das endgültige Dokument den gleichen Zeichensatz haben, ist diese Funktion ausreichend, um Eingaben für die meisten Kontexte eines HTML-Dokuments vorzubereiten. Wenn allerdings die Eingabe Zeichen darstellen kann, die nicht im Zeichensatz des endgültigen Dokuments kodiert sind, und Sie diese Zeichen beibehalten wollen (als numerische oder benannte Entities), kann sowohl diese Funktion als auch htmlentities() (die nur Teilzeichenketten, die benannte Entity-Entsprechungen haben, kodiert) ungenügend sein. Stattdessen muss u. U. mb_encode_numericentity() verwendet werden.
| Zeichen | Ersetzung |
|---|---|
& (Kaufmanns-Und) |
& |
" (doppeltes Anführungszeichen) |
", falls ENT_NOQUOTES
nicht gesetzt ist
|
' (einfaches Anführungszeichen) |
' (für ENT_HTML401)
oder ' (für
ENT_XML1, ENT_XHTML oder
ENT_HTML5), aber nur wenn
ENT_QUOTES gesetzt ist
|
< (kleiner als) |
< |
> (größer als) |
> |
stringDie zu umzuwandelnde Zeichenkette.
flags
Eine Bitmaske von einem oder mehreren der folgenden Flags, die die
Behandlung von Anführungszeichen, ungültigen Zeichenketten und den
genutzten Dokumententyp festlegen. Der Standardwert ist
ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401.
| Name der Konstante | Beschreibung |
|---|---|
ENT_COMPAT |
Wandelt nur doppelte Anführungszeichen um und lässt einfache Anführungszeichen unverändert. |
ENT_QUOTES |
Wandelt sowohl doppelte als auch einfache Anführungszeichen um. |
ENT_NOQUOTES |
Lässt doppelte und einfache Anführungszeichen unverändert. |
ENT_IGNORE |
Verwirft ungültige Code-Unit-Sequenzen, anstatt eine leere Zeichenkette zurückzugeben. Die Nutzung dieser Option ist nicht empfehlenswert, da sie » Auswirkungen auf die Sicherheit haben kann. |
ENT_SUBSTITUTE |
Ersetzt ungültige Code-Unit-Sequenzen mit dem Unicode-Ersatzzeichen U+FFFD (UTF-8) oder � (andernfalls), anstatt eine leere Zeichenkette zurückzugeben. |
ENT_DISALLOWED |
Ersetzt Codepoints, welche in dem angegebenen Dokumenttyp ungültig sind, mit dem Unicode-Ersatzzeichen U+FFFD (UTF-8) oder � (andernfalls), anstatt sie zu belassen. Das kann zum Beispiel nützlich sein, um die Wohlgeformtheit von XML-Dokumenten mit eingebetteten externen Inhalten sicherzustellen. |
ENT_HTML401 |
Behandle Code als HTML 4.01. |
ENT_XML1 |
Behandle Code als XML 1. |
ENT_XHTML |
Behandle Code als XHTML. |
ENT_HTML5 |
Behandle Code als HTML 5. |
encodingEin optionaler Parameter, der die Zeichenkodierung für eine Konvertierung definiert.
Wird der Parameter encoding ausgelassen, so wird
der Wert der Konfigurationsoption
default_charset als Standardwert
dafür verwendet.
Obwohl dieser Parameter technisch gesehen optional ist, wird dringend empfohlen, den korrekten Wert für den jeweiligen Code anzugeben, falls die Konfigurationsoption default_charset für die jeweilige Eingabe möglicherweise falsch gesetzt ist.
Für den Gebrauch dieser Funktion sind die Zeichenkodierungen
ISO-8859-1, ISO-8859-15,
UTF-8, cp866,
cp1251, cp1252 und
KOI8-R tatsächlich äquivalent, vorausgesetzt,
string selbst ist gültig in der
Zeichenkodierung, da die von htmlspecialchars()
betroffenen Zeichen in allen genannten Zeichenkodierungen an gleicher
Position stehen.
Die folgenden Zeichensätze werden unterstützt:
| Zeichensatz | Alias | Beschreibung |
|---|---|---|
| ISO-8859-1 | ISO8859-1 | Westeuropäisch, Latin-1. |
| ISO-8859-5 | ISO8859-5 | Wenig verwendeter kyrillischer Zeichensatz (Latin/Cyrillic). |
| ISO-8859-15 | ISO8859-15 | Westeuropäisch, Latin-9. Enthält das Euro-Zeichen sowie französische und finnische Buchstaben, die in Latin-1(ISO-8859-1) fehlen. |
| UTF-8 | ASCII-kompatibles Multi-Byte 8-Bit Unicode. | |
| cp866 | ibm866, 866 | DOS-spezifischer kyrillischer Zeichensatz. |
| cp1251 | Windows-1251, win-1251, 1251 | Windows-spezifischer kyrillischer Zeichensatz. |
| cp1252 | Windows-1252, 1252 | Windows spezifischer Zeichensatz für westeuropäische Sprachen. |
| KOI8-R | koi8-ru, koi8r | Russisch. |
| BIG5 | 950 | Traditionelles Chinesisch, hauptsächlich in Taiwan verwendet. |
| GB2312 | 936 | Vereinfachtes Chinesisch, nationaler Standard-Zeichensatz. |
| BIG5-HKSCS | Big5 mit Hongkong-spezifischen Erweiterungen; traditionelles Chinesisch. | |
| Shift_JIS | SJIS, SJIS-win, cp932, 932 | Japanisch |
| EUC-JP | EUCJP, eucJP-win | Japanisch |
| MacRoman | Zeichensatz, der von Mac OS verwendet wurde. | |
'' |
Eine leere Zeichenkette aktiviert die Erkennung durch die Kodierung des Skripts (Zend multibyte), default_charset und die aktuelle Sprachumgebung (siehe nl_langinfo() und setlocale()), in dieser Reihenfolge. Nicht empfehlenswert. |
Hinweis: Weitere Zeichensätze sind nicht implementiert. Statt dessen wird die Standard-Kodierung verwendet und eine Warnung ausgegeben.
double_encode
Wird der Parameter double_encode ausgeschaltet,
kodiert PHP bereits existierende HTML-Entities nicht noch einmal.
Standardmäßig werden jedoch alle Zeichen umgewandelt.
Die umgewandelte Zeichenkette.
Enthält string eine in dem übergebenen
encoding ungültige Code-Unit-Sequenz, wird eine
leere Zeichenkette zurückgegeben, sofern weder das
ENT_IGNORE- noch das
ENT_SUBSITUTE-Flag gesetzt sind.
| Version | Beschreibung |
|---|---|
| 8.1.0 |
flags geändert von
ENT_COMPAT zu ENT_QUOTES |
ENT_SUBSTITUTE | ENT_HTML401.
|
Beispiel #1 htmlspecialchars()-Beispiel
<?php
$neu = htmlspecialchars("<a href='test'>Test</a>", ENT_QUOTES);
echo $neu; // <a href='test'>Test</a>
?>Hinweis:
Zu beachten ist, dass diese Funktion nur die o. a. Umwandlungen durchführt. Für eine vollständige Umwandlung in Entities siehe htmlentities().
Hinweis:
Im Fall von mehrdeutigen
flags-Werten gelten die folgenden Regeln:
- Wird weder
ENT_COMPAT,ENT_QUOTESoderENT_NOQUOTESangegeben, ist der StandardwertENT_NOQUOTES.- Werden mehrere von
ENT_COMPAT,ENT_QUOTESundENT_NOQUOTESangegeben, erhältENT_QUOTESden Vorrang, gefolgt vonENT_COMPAT.- Wird weder
ENT_HTML401,ENT_HTML5,ENT_XHTMLnochENT_XML1angegeben, ist der StandardwertENT_HTML401.- Werden mehrere von
ENT_HTML401,ENT_HTML5,ENT_XHTMLundENT_XML1angegeben, erhältENT_HTML5den Vorrang, gefolgt vonENT_XHTML,ENT_XML1undENT_HTML401.- Werden mehrere von
ENT_DISALLOWED,ENT_IGNOREundENT_SUBSTITUTEangegeben, erhältENT_IGNOREden Vorrang, gefolgt vonENT_SUBSTITUTE.
As of PHP 5.4 they changed default encoding from "ISO-8859-1" to "UTF-8". So if you get null from htmlspecialchars or htmlentities
where you have only set
<?php
echo htmlspecialchars($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/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($string, REPLACE_FLAGS, CHARSET);
}
echo html("ñ"); // works
?>
You can do the same for htmlentities()i searched for a while for a script, that could see the difference between an html tag and just < and > placed in the text,
the reason is that i recieve text from a database,
wich is inserted by an html form, and contains text and html tags,
the text can contain < and >, so does the tags,
with htmlspecialchars you can validate your text to XHTML,
but you'll also change the tags, like <b> to <b>,
so i needed a script that could see the difference between those two...
but i couldn't find one so i made my own one,
i havent fully tested it, but the parts i tested worked perfect!
just for people that were searching for something like this,
it may looks big, could be done easier, but it works for me, so im happy.
<?php
function fixtags($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!!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.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_SUBSTITUTEAnother thing important to mention is that
htmlspecialchars(NULL)
returnes an empty string and not NULL!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', /*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", $result6, "<br />\r\n";
?>
will produce:
HTML 4.01 (will NOT recognize single quote, but Euro):
ampersand(&), double quote("), single quote('), less than(<), greater than(>), numeric entities(&"'<>), HTML 5 entities(+,!$(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€)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.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", $text);
?>
I don't like that but I don't find other solution... :/If you use htmlspecialchars() to escape any HTML attribute, make sure use double quote instead of single quote for the attribute.
For Example,
> Wrap with Single Quote
<?php
echo "<p title='" . htmlspecialchars("Hello\"s\'world") . "'">
// title will end up Hello"s\ and rest of the text after single quote will be cut off.
?>
> Wrap with Double quote :
<?php
echo '<p title="' . htmlspecialchars("Hello\"s\'world") . '"'>
// title will show up correctly as Hello"s'world
?>Just a few notes on how one can use htmlspecialchars() and htmlentities() to filter user input on forms for later display and/or database storage...
1. Use htmlspecialchars() to filter text input values for html input tags. i.e.,
echo '<input name=userdata type=text value="'.htmlspecialchars($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.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.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).Actually, if you're using >= 4.0.5, this should theoretically be quicker (less overhead anyway):
$text = str_replace(array(">", "<", """, "&"), array(">", "<", "\"", "&"), $text);Be aware of the encoding of your source files!!!
Some of the suggestions here make reference to workarounds where you hard-code an encoding.
<?php
echo htmlspecialchars('<b>Wörmann</b>'); // Why isn't this working?
?>
As it turns out, it may actually be your text editor that is to blame.
As of PHP 5.4, htmlspecialchars now defaults to the UTF-8 encoding. That said, many text editors default to non-UTF encodings like ISO-8859-1 (i.e. Latin-1) or WIN-1252. If you change the encoding of the file to UTF-8, the code above will now work (i.e. the ö is encoded differently in UTF-8 and ISO-8859-1, and you need the UTF-8 version).
Make sure you are editing in UTF-8 Unicode mode! Check your UI or manual for how to convert files to Unicode. It's also a good idea to figure out where to look in your UI to see what the current file encoding is.Problem
In many PHP legacy products the function htmlspecialchars($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, $charset);
}
or 2b crate a new PHP-file containing the three functions mentioned above, let's say, z. B. htmlXfunctions.inc.php and include it on the first line of every PHP-file in your legacy product like this: require_once('htmlXfunctions.inc.php').I had problems with spanish special characters. So i think in using htmlspecialchars but my strings also contain HTML.
So I used this :) Hope it help
<?php
function htmlspanishchars($str)
{
return str_replace(array("<", ">"), array("<", ">"), htmlspecialchars($str, ENT_NOQUOTES, "UTF-8"));
}
?>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!"People, don't use ereg_replace for the most simple string replacing operations (replacing constant string with another).
Use str_replace.