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urldecode

(PHP 4, PHP 5)

urldecode — 解码已编码的 URL 字符串

说明

string urldecode ( string $str )

解码给出的已编码字符串中的任何 %##。返回解码后的字符串。

Example #1 urldecode() 例子

<?php
$a = explode('&', $QUERY_STRING);
$i = 0;
while ($i < count($a)) {
    $b = split('=', $a[$i]);
    echo 'Value for parameter ', htmlspecialchars(urldecode($b[0])),
         ' is ', htmlspecialchars(urldecode($b[1])), "<br />\n";
    $i++;
}
?>

参见 urlencode()，rawurlencode() 和 rawurldecode()。

URL 函数
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PHP手册
PHP手册 - N: 解码已编码的 URL 字符串

用户评论:

jodybrabec at gmail dot com (22-Dec-2011 12:01)

Gets rid of 'amp;' in $_GET param names - so $_GET['amp;myVar'] becomes $_GET['myVar']
Made this because sometimes '&amp;' will wind up in the URL, as in:
http://example.com/index.php?aaa=111&amp;myVar=222
Call this function at the top of your php page:
unmake_amps();

<?php
function unmake_amps() {
    foreach ($_GET as $g_param=>$g_value) {
        if (preg_match('/^amp\;(.*)$/i', $g_param)) {
            $g_paramNew = preg_replace('/^amp\;(.*)$/i', '$1', $g_param);
            unset($_GET[$g_param]);
            if ($g_paramNew != '') {
                // Only if $g_paramNew has a value, becaues sometimes '&amp;' winds up at the end of a url ($_GET['amp;'])
                $_GET[$g_paramNew] = $g_value;
            }
        }
    }
}
?>

Geek note: only for one-dimensional $_GET arrays - too lazy to make this a recursive function.

alejandro at devenet dot net (15-Dec-2010 02:27)

When the client send Get data, utf-8 character encoding have a tiny problem with the urlencode.
Consider the "?" 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

<?php
$x = $_GET['myvar'];
?>

$x store: in the first case "?" (bad) and in the second case "?" (good)

To fix that, you can use this function:

<?php
function to_utf8( $string ) {
// From http://w3.org/International/questions/qa-forms-utf-8.html
    if ( preg_match('%^(?:
      [\x09\x0A\x0D\x20-\x7E]            # ASCII
    | [\xC2-\xDF][\x80-\xBF]             # non-overlong 2-byte
    | \xE0[\xA0-\xBF][\x80-\xBF]         # excluding overlongs
    | [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2}  # straight 3-byte
    | \xED[\x80-\x9F][\x80-\xBF]         # excluding surrogates
    | \xF0[\x90-\xBF][\x80-\xBF]{2}      # planes 1-3
    | [\xF1-\xF3][\x80-\xBF]{3}          # planes 4-15
    | \xF4[\x80-\x8F][\x80-\xBF]{2}      # plane 16
)*$%xs', $string) ) {
        return $string;
    } else {
        return iconv( 'CP1252', 'UTF-8', $string);
    }
}
?>

and assign in this way:

<?php
$x = to_utf8( $_GET['myvar'] );
?>

$x store: in the first case "?" (good) and in the second case "?" (good)

Solve a lot of i18n problems.

Please fix the auto-urldecode of $_GET var in the next PHP version.

Bye.

Alejandro Salamanca

chrisstocktonaz at gmail dot com (29-Jan-2010 06:39)

I was looking for a fast way to build a string dsn from a key => value pair array. I came up with the following, simple enough for my purposes.

<?php

$dsn = Array(
  'host' => 'localhost',
  'port' => 80,
  'user' => 'foo',
  'pass' => 'R(I%!JAKSJ(asd'
);

$dsn = urldecode(http_build_query($dsn, NULL, ';'));

var_dump($dsn); // host=localhost;port=80;user=foo;pass=R(I%!JAKSJ(asd
?>

mail dot roliveira at gmail dot com (19-May-2009 12:50)

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.:

<?php
// first use encodeURIComponent on javascript to encode the string
// receive json string and prepare it to json_decode
$jsonStr = stripslashes ($_POST['action']);
// decode to php object
$json = json_decode ($jsonStr);

// $json is now a php object
?>

Jan Vratny (12-Jun-2008 01:09)

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).

Joe (03-Apr-2008 07:11)

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.

<?php
echo stripslashes(nl2br($_POST['message']));
?>

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')

mkaganer at gmail dot com (04-Dec-2007 10:58)

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):

<?php
  function utf8_urldecode($str) {
    $str = preg_replace("/%u([0-9a-f]{3,4})/i","&#x\\1;",urldecode($str));
    return html_entity_decode($str,null,'UTF-8');;
  }
?>

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

pedantic at hotmail co jp (16-Nov-2006 04:22)

The following function will decode %uXXXX
sequentially, without temporary data.

<?php

function decode_unicode_url($str)
{
  $res = '';

  $i = 0;
  $max = strlen($str) - 6;
  while ($i <= $max)
  {
    $character = $str[$i];
    if ($character == '%' && $str[$i + 1] == 'u')
    {
      $value = hexdec(substr($str, $i + 2, 4));
      $i += 6;

      if ($value < 0x0080) // 1 byte: 0xxxxxxx
        $character = chr($value);
      else if ($value < 0x0800) // 2 bytes: 110xxxxx 10xxxxxx
        $character =
            chr((($value & 0x07c0) >> 6) | 0xc0)
          . chr(($value & 0x3f) | 0x80);
      else // 3 bytes: 1110xxxx 10xxxxxx 10xxxxxx
        $character =
            chr((($value & 0xf000) >> 12) | 0xe0)
          . chr((($value & 0x0fc0) >> 6) | 0x80)
          . chr(($value & 0x3f) | 0x80);
    }
    else
      $i++;

    $res .= $character;
  }

  return $res . substr($str, $i);
}
?>

Simple test with japanese characters,
combined with urldecode:

<?php

$str = decode_unicode_url('%u65E5%u672C%u8A9E');
print(mb_convert_encoding(urldecode($str), "sjis", "euc-jp, utf-8, sjis") . '<br/>');
?>

tikitiki at mybboard dot com (05-Oct-2006 11:56)

Here is a rewritten example that does the same thing but runs cleaner.

<?php
$a = explode('&', $QUERY_STRING);

foreach($a as $key => $b)
{
   $b = split('=', $b);
   echo 'Value for parameter '.htmlspecialchars(urldecode($b[0])).' is '.htmlspecialchars(urldecode($b[1]))."<br />\n";
}
?>

jeffreyd at davis at gmail dot com (18-Aug-2006 09:05)

As a useful variation on the function rosty dot kerei at gmail dot com wrote, I made a quick modification to just plain output the html code. That way a javascript encoded url (or say, a get variable) can actually be written back to the user.

function unicode_urldecode($url)
{
   preg_match_all('/%u([[:alnum:]]{4})/', $url, $a);
 
   foreach ($a[1] as $uniord)
   {
       $utf = '&#x' . $uniord . ';';
       $url = str_replace('%u'.$uniord, $utf, $url);
   }
 
   return urldecode($url);
}

Visual (18-May-2006 08:02)

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.

rosty dot kerei at gmail dot com (19-Apr-2006 05:40)

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 < 128)
        {
            $utf = chr($dec);
        }
        else if ($dec < 2048)
        {
            $utf = chr(192 + (($dec - ($dec % 64)) / 64));
            $utf .= chr(128 + ($dec % 64));
        }
        else
        {
            $utf = chr(224 + (($dec - ($dec % 4096)) / 4096));
            $utf .= chr(128 + ((($dec % 4096) - ($dec % 64)) / 64));
            $utf .= chr(128 + ($dec % 64));
        }
       
        $url = str_replace('%u'.$uniord, $utf, $url);
    }
   
    return urldecode($url);
}

Aardvark (07-Mar-2006 09:20)

The function below can be used to convert a query parameter resulting from applying the JavaScript escape function to a Unicode string back to Unicode.  The function was modified from a previously published function to handle escaped ASCII values in the range 128-255 which are converted to standard (and not Unicode) escapes by the escape function.  The option parameter allows an altenative encoding to UTF-8 to be apploed.  (More and related info can be found at http://www.kanolife.com/escape/). 

function code2utf($num){
  if($num<128)
    return chr($num);
  if($num<1024)
    return chr(($num>>6)+192).chr(($num&63)+128);
  if($num<32768)
    return chr(($num>>12)+224).chr((($num>>6)&63)+128)
          .chr(($num&63)+128);
  if($num<2097152)
    return chr(($num>>18)+240).chr((($num>>12)&63)+128)
          .chr((($num>>6)&63)+128).chr(($num&63)+128);
  return '';
}

function unescape($strIn, $iconv_to = 'UTF-8') {
  $strOut = '';
  $iPos = 0;
  $len = strlen ($strIn);
  while ($iPos < $len) {
    $charAt = substr ($strIn, $iPos, 1);
    if ($charAt == '%') {
      $iPos++;
      $charAt = substr ($strIn, $iPos, 1);
      if ($charAt == 'u') {
        // Unicode character
        $iPos++;
        $unicodeHexVal = substr ($strIn, $iPos, 4);
        $unicode = hexdec ($unicodeHexVal);
        $strOut .= code2utf($unicode);
        $iPos += 4;
      }
      else {
        // Escaped ascii character
        $hexVal = substr ($strIn, $iPos, 2);
        if (hexdec($hexVal) > 127) {
          // Convert to Unicode
          $strOut .= code2utf(hexdec ($hexVal));
        }
        else {
          $strOut .= chr (hexdec ($hexVal));
        }
        $iPos += 2;
      }
    }
    else {
      $strOut .= $charAt;
      $iPos++;
    }
  }
  if ($iconv_to != "UTF-8") {
    $strOut = iconv("UTF-8", $iconv_to, $strOut);
  }  
  return $strOut;
}

spam at soiland dot no (06-Apr-2005 01:45)

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 &amp; 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 &copy;  (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:

<a href="?name=stain&amp;fish=knott">mylink</a>

Note that the decoding of &amp; 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
<input name="fish" value="fish &amp; fries" />.

Matt Johnson (26-Dec-2004 12:49)

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

Evil PHP:

<?php
# BAD CODE! DO NOT USE!
$term = urldecode($_GET['sterm']);
?>

Good PHP:

<?php
$term = $_GET['sterm'];
?>

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 < 2.0.11.

caribe at flash-brasil dot com dot br (13-Oct-2003 09:55)

To allow urldecode to work with Brazilian characters as and other just place this header command :

header('Content-type: text/html; charset=UTF-8');

(09-Oct-2003 04:17)

nataniel, your function needs to be corrected as follows:

------------------------------------------------------------
function unicode_decode($txt) {
  return ereg_replace('%u([[:alnum:]]{4})', '&#x\1;',$txt);
}
------------------------------------------------------------

since some codes does not begin with %u0.

tomas at penajaca dot com dot br (21-Jul-2003 07:14)

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");
}

regindk at hotmail dot com (24-Apr-2003 02:00)

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 &amp;
Like this:
$str = "pippo.php?param1=&amp;reg_var";
echo rawurldecode($str);

bellani at upgrade4 dot it (11-Mar-2003 06:12)

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.

<a href="pippo.php?param1=&reg_var=">go</a>

you will get a wrong url like this

"pippo.php?param1=_var"

Simply add a space between "&" and "reg_var" and it will work!

<a href="pippo.php?param1=& reg_var=">go</a>

"pippo.php?param1=&%20reg_var"

Works!!

smolniy at mtu dot ru (07-Feb-2003 10:42)

For compatibility of new and old brousers:

%xx -> char
%u0xxxx -> char

function unicode_decode($txt) {
 $txt = ereg_replace('%u0([[:alnum:]]{3})', '&#x\1;',$txt);
 $txt = ereg_replace('%([[:alnum:]]{2})', '&#x\1;',$txt);
 return ($txt);
}

igjav at cesga dot es (16-May-2002 07:48)

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 < $len) {
        $charAt = substr ($source, $pos, 1);
        if ($charAt == '') {
            $char2 = substr($source, $pos, 2);
            $decodedStr .= htmlentities(utf8_decode($char2),ENT_QUOTES,'ISO-8859-1');
            $pos += 2;
        }
        elseif(ord($charAt) > 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;
}