urldecode()

(PHP 4, PHP 5, PHP 7)

解码已编码的 URL 字符串

说明

解码给出的已编码字符串中的任何%##。加号（'+'）被解码成一个空格字符。

参数

• $str：要解码的字符串。

返回值

返回解码后的字符串。

范例

注释

超全局变量$_GET和$_REQUEST已经被解码了。对$_GET或$_REQUEST里的元素使用urldecode()将会导致不可预计和危险的结果。

参见

• urlencode()编码 URL 字符串
• rawurlencode()按照 RFC 3986 对 URL 进行编码
• rawurldecode()对已编码的 URL 字符串进行解码
• » RFC 3986

When the client send Get data, utf-8 character encoding have a tiny problem with the urlencode.
Consider the "º" character. 
Some clients can send (as example)
foo.php?myvar=%BA
and another clients send
foo.php?myvar=%C2%BA (The "right" url encoding)
in this scenary, you assign the value into variable $x

$x store: in the first case "" (bad) and in the second case "º" (good)
To fix that, you can use this function:

and assign in this way:

$x store: in the first case "º" (good) and in the second case "º" (good)
Solve a lot of i18n problems.
Please fix the auto-urldecode of $_GET var in the next PHP version.
Bye.
Alejandro Salamanca

If you are escaping strings in javascript and want to decode them in PHP with urldecode (or want PHP to decode them automatically when you're putting them in the query string or post request), you should use the javascript function encodeURIComponent() instead of escape(). Then you won't need any of the fancy custom utf_urldecode functions from the previous comments.

A reminder: if you are considering using urldecode() on a $_GET variable, DON'T!
Evil PHP:

Good PHP:

The webserver will arrange for $_GET to have been urldecoded once already by the time it reaches you!
Using urldecode() on $_GET can lead to extreme badness, PARTICULARLY when you are assuming "magic quotes" on GET is protecting you against quoting.
Hint: script.php?sterm=%2527 [...]
PHP "receives" this as %27, which your urldecode() will convert to "'" (the singlequote). This may be CATASTROPHIC when injecting into SQL or some PHP functions relying on escaped quotes -- magic quotes rightly cannot detect this and will not protect you!
This "common error" is one of the underlying causes of the Santy.A worm which affects phpBB 
For compatibility of new and old brousers:
%xx -> char
%u0xxxx -> char
function unicode_decode($txt) {
 $txt = ereg_replace('%u0([[:alnum:]]{3})', '\1;',$txt);
 $txt = ereg_replace('%([[:alnum:]]{2})', '\1;',$txt);
 return ($txt);
}
Even if $_GET and $_REQUEST are decoded automatically, some other variables aren't. For example $_SERVER["REQUEST_URI"]. Remember to decode it when using.
mkaganer at gmail dot com:
try using encodeURI() instead of encode() in javascript. That worked for me, while your solution did not on __some__ national characters (at least in IE6).
This function doesn't decode unicode characters. I wrote a function that does.
function unicode_urldecode($url)
{
  preg_match_all('/%u([[:alnum:]]{4})/', $url, $a);
  
  foreach ($a[1] as $uniord)
  {
    $dec = hexdec($uniord);
    $utf = '';
    
    if ($dec 
It's worth pointing out that if you are using AJAX and need to encode strings that are being sent to a PHP application, you may not need to decode them in PHP.

Will properly output a message sent with the javascript code if the message is encoded:
message = encodeURIComponent(message)
And is sent with an AJAX POST request with the header:
ajaxVar.setRequestHeader('Content-type', 'application/x-www-form-urlencoded')
B.H.
I had troubles converting Unicode-encoded data in $_GET (like this: %u05D8%u05D1%u05E2) which is generated by JavaScript's escape() function to UTF8 for server-side processing.
Finally, i've found a simple solution (only 3 lines of code) that does it (at least in my configuration):

note that documentation for html_entity_decode() states that "Support for multi-byte character sets was added at PHP 5.0.0" so this might not work for PHP 4
urldecode does not decode "%0" bypassing it. I can cause troble when you are working with fixed lenght strings.
You can you the function below.
function my_urldecode($string){
 $array = split ("%",$string);
 if (is_array($array)){
  while (list ($k,$v) = each ($array)){
    $ascii = base_convert ($v,16,10);
    $ret .= chr ($ascii);
  }
 }
 return ("$ret");
}
It seems that the $_REQUEST global parameter is automatically decoded only if the content type is application/x-www-form-urlencoded.
if the content type is multipart/form-data. the data remains un-decoded. and we have to manually handle the decoding at our end
When sending a string via AJAX POST data which contains an ampersand (&), be sure to use encodeURIComponent() on the javascript side and use urldecode() on the php side for whatever variable that was. I've found it tricky to transfer raw ampersands and so this is what worked for me:

For some reason, a variable with an ampersand would stay encoded while other POST variables were automatically decoded. I concatenated data from an html form before submitting, in case you wish to know what happened on the browser end.
nataniel, your function needs to be corrected as follows:
------------------------------------------------------------
function unicode_decode($txt) {
 return ereg_replace('%u([[:alnum:]]{4})', '\1;',$txt);
}
------------------------------------------------------------
since some codes does not begin with %u0.
Send json to PHP via AJAX (POST)
If you send json data via ajax, and encode it with encodeURIComponent in javascript, then on PHP side, you will have to do stripslashes on your $_POST['myVar'].
After this, you can do json_decode on your string.
Ex.: 
If you have a "html reserved word" as variable name (i.e. "reg_var") and you pass it as an argument you will get a wrong url. i.e.
go
you will get a wrong url like this 
"pippo.php?param1=_var"
Simply add a space between "&" and "reg_var" and it will work!
go
"pippo.php?param1=&%20reg_var"
Works!!
About reg_var and "html reserved words"
Do not add spaces as the user suggests.
Instead, do what all HTML standards says and encode & in URLs as & in your HTML. 
The reason why & works "most of the time" is that browsers are forgiving and just decode the & as the &-sign. This breaks whenever you have a variable that matches an HTML entity, like "gt" or "copy" or whatever. &copy in your URL will be interpreted as © (the ; is not mandatory in SGML as it is "implied". In XML it is mandatory.).  The result will be the same as if you had inserted the actual character into your source code, for instance by pressing alt-0169 and actually inserted  in your HTML.
Ie, use:
mylink
Note that the decoding of & to & is done in the browser, and it's done right after splitting the HTML into tags, attributes and content, but it works both for attributes and content.
This mean you should &entitify all &-s in any other HTML attributes as well, such as in a form with 
.
This seems to decode correctly between most browsers and charater coding configurations. Specially indicated for direct parsing of URL as it comes on environment variables:
function crossUrlDecode($source) {
  $decodedStr = '';
  $pos = 0;
  $len = strlen($source);
  while ($pos  127) {
      $decodedStr .= "".ord($charAt).";";
      $pos++;
    }
    elseif($charAt == '%') {
      $pos++;
      $hex2 = substr($source, $pos, 2);
      $dechex = chr(hexdec($hex2));
      if($dechex == '') {
        $pos += 2;
        if(substr($source, $pos, 1) == '%') {
          $pos++;
          $char2a = chr(hexdec(substr($source, $pos, 2)));
          $decodedStr .= htmlentities(utf8_decode($dechex . $char2a),ENT_QUOTES,'ISO-8859-1');
        }
        else {
          $decodedStr .= htmlentities(utf8_decode($dechex));
        }
      }
      else {
        $decodedStr .= $dechex;
      }
      $pos += 2;
    }
    else {
      $decodedStr .= $charAt;
      $pos++;
    }
  }
  return $decodedStr;
}
About: bellani at upgrade4 dot it
$str = "pippo.php?param1=&reg_var";
echo rawurldecode($str);
Gives:
pippo.php?param1=_var
Instead of using a space you should exchange & with the correct W3C &
Like this:
$str = "pippo.php?param1=&reg_var";
echo rawurldecode($str);
To allow urldecode to work with Brazilian characters as and other just place this header command :
header('Content-type: text/html; charset=UTF-8');
 

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