parse_str()

(PHP 4, PHP 5, PHP 7)

将字符串解析成多个变量

说明

parse_str (string $encoded_string [, array &$result ] ) : void

如果 $encoded_string 是 URL 传递入的查询字符串（query string），则将它解析为变量并设置到当前作用域（如果提供了 $result 则会设置到该数组里）。

参数

$encoded_string: 输入的字符串。
$result: 如果设置了第二个变量 $result，变量将会以数组元素的形式存入到这个数组，作为替代。

Warning
极度不建议 在没有 $result 参数的情况下使用此函数，并且在 PHP 7.2 中将废弃不设置参数的行为。

在函数中动态设置变量会和 register_globals 有同样的问题。

阅读「安全」中使用 Register Globals 的章节，解释了它为什么是危险的。

返回值

没有返回值。

更新日志

版本	说明
7.2.0	不带第二个参数的情况下使用 parse_str() 会产生 `E_DEPRECATED` 警告。

范例

parse_str() 的使用

<?php
$str = "first=value&arr[]=foo+bar&arr[]=baz";
// 推荐用法
parse_str($str, $output);
echo $output['first'];  // value
echo $output['arr'][0]; // foo bar
echo $output['arr'][1]; // baz
// 不建议这么用
parse_str($str);
echo $first;  // value
echo $arr[0]; // foo bar
echo $arr[1]; // baz
?>

由于 PHP 的变量名不能带「点」和「空格」，所以它们会被转化成下划线。用本函数带 $result 参数，也会应用同样规则到数组的键名。

parse_str() 名称改写

<?php
parse_str("My Value=Something");
echo $My_Value; // Something
parse_str("My Value=Something", $output);
echo $output['My_Value']; // Something
?>

注释

Note:
所有创建的变量(或者在设置第二个参数的情况下，返回数组里的值)，都已经 urldecode() 了。

Note:
要获取当前的 QUERY_STRING，可以使用 $_SERVER['QUERY_STRING'] 变量。所以你可能想要阅读来自 PHP 之外的变量这个章节。

Note:
本函数受 magic_quotes_gpc 设置的影响，和 $_GET、 $_POST 在 PHP 中填充变量相似， parse_str() 也使用了同样的机制。

参见

parse_url()解析 URL，返回其组成部分
pathinfo()返回文件路径的信息
http_build_query()生成 URL-encode 之后的请求字符串
urldecode()解码已编码的 URL 字符串

It bears mentioning that the parse_str builtin does NOT process a query string in the CGI standard way, when it comes to duplicate fields. If multiple fields of the same name exist in a query string, every other web processing language would read them into an array, but PHP silently overwrites them:
<?php
# silently fails to handle multiple values
parse_str('foo=1&foo=2&foo=3');
# the above produces:
$foo = array('foo' => '3');
?>
Instead, PHP uses a non-standards compliant practice of including brackets in fieldnames to achieve the same effect.
<?php
# bizarre php-specific behavior
parse_str('foo[]=1&foo[]=2&foo[]=3');
# the above produces:
$foo = array('foo' => array('1', '2', '3') );
?>
This can be confusing for anyone who's used to the CGI standard, so keep it in mind. As an alternative, I use a "proper" querystring parser function:
<?php
function proper_parse_str($str) {
 # result array
 $arr = array();
 # split on outer delimiter
 $pairs = explode('&', $str);
 # loop through each pair
 foreach ($pairs as $i) {
  # split into name and value
  list($name,$value) = explode('=', $i, 2);
  
  # if name already exists
  if( isset($arr[$name]) ) {
   # stick multiple values into an array
   if( is_array($arr[$name]) ) {
    $arr[$name][] = $value;
   }
   else {
    $arr[$name] = array($arr[$name], $value);
   }
  }
  # otherwise, simply stick it in a scalar
  else {
   $arr[$name] = $value;
  }
 }
 # return result array
 return $arr;
}
$query = proper_parse_str($_SERVER['QUERY_STRING']);
?>

if you need custom arg separator, you can use this function. it returns parsed query as associative array.
<?php
/**
 * Parses http query string into an array
 * 
 * @author Alxcube <alxcube@gmail.com>
 * 
 * @param string $queryString String to parse
 * @param string $argSeparator Query arguments separator
 * @param integer $decType Decoding type
 * @return array
 */
function http_parse_query($queryString, $argSeparator = '&', $decType = PHP_QUERY_RFC1738) {
    $result       = array();
    $parts       = explode($argSeparator, $queryString);
    foreach ($parts as $part) {
        list($paramName, $paramValue)  = explode('=', $part, 2);
        switch ($decType) {
            case PHP_QUERY_RFC3986:
                $paramName   = rawurldecode($paramName);
                $paramValue   = rawurldecode($paramValue);
                break;
            case PHP_QUERY_RFC1738:
            default:
                $paramName   = urldecode($paramName);
                $paramValue   = urldecode($paramValue);
                break;
        }
        
        if (preg_match_all('/\[([^\]]*)\]/m', $paramName, $matches)) {
            $paramName   = substr($paramName, 0, strpos($paramName, '['));
            $keys      = array_merge(array($paramName), $matches[1]);
        } else {
            $keys      = array($paramName);
        }
        
        $target     = &$result;
        
        foreach ($keys as $index) {
            if ($index === '') {
                if (isset($target)) {
                    if (is_array($target)) {
                        $intKeys    = array_filter(array_keys($target), 'is_int');
                        $index = count($intKeys) ? max($intKeys)+1 : 0;
                    } else {
                        $target = array($target);
                        $index = 1;
                    }
                } else {
                    $target     = array();
                    $index     = 0;
                }
            } elseif (isset($target[$index]) && !is_array($target[$index])) {
                $target[$index] = array($target[$index]);
            }
            $target     = &$target[$index];
        }
        if (is_array($target)) {
            $target[]  = $paramValue;
        } else {
            $target   = $paramValue;
        }
    }
    return $result;
}
?>

just a heads up with the example above:
?var[]=123 - the [] has to be urlencoded.
var names and var values - both have to be urlencoded!

That's not says in the description but max_input_vars directive affects this function. If there are more input variables on the string than specified by this directive, an E_WARNING is issued, and further input variables are truncated from the request.

If the arr argument is provided, all its existing elements are removed.

Vladimir: the function is OK in how it deals with &amp;.
&amp; must only be used when outputing URLs in HTML/XML data.
You should ask yourself why you have &amp; in your URL when you give it to parse_str.

As of PHP 5, you can do the exact opposite with http_build_query(). Just remember to use the optional array output parameter.
This is a very useful combination if you want to re-use a search string url, but also slightly modify it:
Example:
<?
$url1 = "action=search&interest[]=sports&interest[]=music&sort=id";
$str = parse_str($url1, $output);
// Modifying criteria:
$output['sort'] = "interest";
$url2 = http_build_query($output);
echo "<br>url1: ".$url1;
echo "<br>url2: ".$url2;
?>
Results in:
url1: action=search&interest[]=sports&interest[]=music&sort=id
url2: action=search&interest[0]=sports&interest[1]=music&sort=interest
(Array indexes are automatically created.)

Note that the characters "." and " " (empty space) will be converted to "_". The characters "[" and "]" have special meaning: They represent arrays but there seems to be some weird behaviour, which I don't really understand:
<?php
// Note: "[" = %5B, "]" = %5D
/*
"v][=a" produces ("[" gets replaced by "_"):
Array
(
  [v]_] => a
)
*/
parse_str("v%5D%5B=a", $r);
print_r($r);
/*
"v][[=a" produces (first "[" gets replaced by "_", but not all following):
Array
(
  [v]_[] => a
)
*/
parse_str("v%5D%5B%5B=a", $r);
print_r($r);
?>

The array to be populated does not need to be defined before calling the function:
<?php
error_reporting(E_ALL  |  E_STRICT);
parse_str('var=value', $array);
?>
This will not produce a notice.

Here is a little function that does the opposite of the parse_str function. It will take an array and build a query string from it.
<?php
/* Converts an array of parameters into a query string to be appended to a URL.
 *
 * @return string       : Query string to append to a URL.
 * @param  array  $array   : Array of parameters to append to the query string.
 * @param  string  $parent  : This should be left blank (it is used internally by the function).
 */
function append_params($array, $parent='')
{
  $params = array();
  foreach ($array as $k => $v)
  {
    if (is_array($v))
      $params[] = append_params($v, (empty($parent) ? urlencode($k) : $parent . '[' . urlencode($k) . ']'));
    else
      $params[] = (!empty($parent) ? $parent . '[' . urlencode($k) . ']' : urlencode($k)) . '=' . urlencode($v);
  }
  $sessid = session_id();
  if (!empty($parent)  ||  empty($sessid))
    return implode('&', $params);
  // Append the session ID to the query string if we have to.
  $sessname = session_name();
  if (ini_get('session.use_cookies'))
  {
    if (!ini_get('session.use_only_cookies') && (!isset($_COOKIE[$sessname])  ||  ($_COOKIE[$sessname] != $sessid)))
      $params[] = $sessname . '=' . urlencode($sessid);
  }
  elseif (!ini_get('session.use_only_cookies'))
    $params[] = $sessname . '=' . urlencode($sessid);
  return implode('&', $params);
}
?>
Note that the function will also append the session ID to the query string if it needs to be.

CONVERT ANY FORMATTED STRING INTO VARIABLES
I developed a online payment solution for credit cards using a merchant, and this merchant returns me an answer of the state of the transaction like this:
estado=1,txnid=5555444-8454445-4455554,monto=100.00
to have all that data into variables could be fine for me! so i use str_replace(), the problem is this function recognizes each group of variables with the & character... and i have comma separated values... so i replace comma with &
<?php
$string = "estado=1,txnid=5555444-8454445-4455554,monto=100.00";
$string = str_replace(",","&",$string);
parse_str($string);
echo $monto; // outputs 100.00
?>

proper_parse_str works great and I like that it doesn't replace spaces with underbars, but should urldecode $value

<? 
//by shimon doodkin
 $url_form=url_to_form($url);
 echo '<form action="'.$url_form['action'].'" method="get">';
 echo $url_form['hidden'];
 echo '<input name="otherfiled" type="text">';
 echo '<input type="submit">';
 echo '</form>';
 function url_to_form($url)
 {
 $url=split('\?',$url,2);
 $action=$url[0];
 $hidden="";
 if(isset($url[1]))
 {
  $pairs=split('&',$url[1]);
  foreach($pairs as $pair)
  {
  $pair=split('=',$pair,2);
  $name=$pair[0];
  if(isset($pair[1]))
   $value=$pair[1];
  else
   $value='';
  $name=$name;
  $value=htmlspecialchars($value);
  if($name!='')
   $hidden.='<hidden name="'.$name.'" value="'.$value.'">';
  }
 }
 return array('action'=>$action,'hidden'=>$hidden);
 }
?>

If you wish a version of parse_str sans magic quotes, the following will do the trick:
<?php
function parse_query($str) {
  $pairs = explode('&', $str);
  foreach($pairs as $pair) {
    list($name, $value) = explode('=', $pair, 2);
    global $$name;
    $$name = $value;
  }
}
?>

This is probably a better solution than below. The first line makes sure the file doesn't exist then the second line directs all requests to a script. No need to output a 200 header with this method either.
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^ index.php   [L]

Vladimir Kornea wrote on 8 Sep 2006:
"This function is confused by ampersands (&) being encoded as HTML entities (&amp;)"
Well, it would be - it's not supposed to be passed html entities, that's a different encoding scheme. This function does correctly decode url encoded params for you though (with the rawurlencode rather than urlencode, ie '+' is translated to a space).

If you are trying to preserve a complex array, the function serialize might be better than http_build_query or other methods of making a query string.

In Kent's solution you may wish to switch "urldecode" into "rawurldecode" if you'd like to get rid of the [annoying] plus '+' converted to space ' ' translation.

You may want to parse the query string into an array. 
<?php
/**
 * Similar to parse_str. Returns false if the query string or URL is empty. Because we're not parsing to 
 * variables but to array key entries, this function will handle ?[]=1&[]=2 "correctly."
 *
 * @return array Similar to the $_GET formatting that PHP does automagically.
 * @param string $url A query string or URL 
 * @param boolean $qmark Find and strip out everything before the question mark in the string
*/
function parse_query_string($url, $qmark=true)
{
  if ($qmark) {
    $pos = strpos($url, "?");
    if ($pos !== false) {
      $url = substr($url, $pos + 1);
    }
  }
  if (empty($url))
    return false;
  $tokens = explode("&", $url);
  $urlVars = array();
  foreach ($tokens as $token) {
    $value = string_pair($token, "=", "");
    if (preg_match('/^([^\[]*)(\[.*\])$/', $token, $matches)) {
      parse_query_string_array($urlVars, $matches[1], $matches[2], $value);
    } else {
      $urlVars[urldecode($token)] = urldecode($value);
    }
  }
  return $urlVars;
}
/**
 * Utility function for parse_query_string. Given a result array, a starting key, and a set of keys formatted like "[a][b][c]" 
 * and the final value, updates the result array with the correct PHP array keys.
 *
 * @return void
 * @param array $result A result array to populate from the query string
 * @param string $k The starting key to populate in $result
 * @param string $arrayKeys The key list to parse in the form "[][a][what%20ever]"
 * @param string $value The value to place at the destination array key
*/
function parse_query_string_array(&$result, $k, $arrayKeys, $value)
{
  if (!preg_match_all('/\[([^\]]*)\]/', $arrayKeys, $matches))
    return $value;
  if (!isset($result[$k])) {
    $result[urldecode($k)] = array();
  }
  $temp =& $result[$k];
  $last = urldecode(array_pop($matches[1]));
  foreach ($matches[1] as $k) {
    $k = urldecode($k);
    if ($k === "") {
      $temp[] = array();
      $temp =& $temp[count($temp)-1];
    } else if (!isset($temp[$k])) {
      $temp[$k] = array();
      $temp =& $temp[$k];
    }
  }
  if ($last === "") {
    $temp[] = $value;
  } else {
    $temp[urldecode($last)] = $value;
  }
}
/**
* Breaks a string into a pair for a common parsing function. 
*
* The string passed in is truncated to the left half of the string pair, if any, and the right half, if anything, is returned.
*
* An example of using this would be:
* <code>
* $path = "Account.Balance";
* $field = string_pair($path);
* 
* $path is "Account"
* $field is "Balance"
*
* $path = "Account";
* $field = string_pair($path);
*
* $path is "Account"
* $field is false
* </code>
*
* @return string The "right" portion of the string is returned if the delimiter is found.
* @param string $a A string to break into a pair. The "left" portion of the string is returned here if the delimiter is found.
* @param string $delim The characters used to delimit a string pair
* @param mixed $default The value to return if the delimiter is not found in the string
* @desc 
*/
function string_pair(&$a, $delim='.', $default=false)
{
  $n = strpos($a, $delim);
  if ($n === false)
    return $default;
  $result = substr($a, $n+strlen($delim));
  $a = substr($a, 0, $n);
  return $result;
}
?>

I wrote a pair of functions using parse_str() that will write values in an array to a textfile and vice versa, read those values from the textfile back into the array. Quite useful if you need to store lots of data but don't have access to SQL.
Save the array by calling cfg_save($filename,$array) and load it back using $array=cfg_load($filename)
<?php
$newline="";
function cfg_load($cfgfile){
  global $newline;
  $setting="";
  if(file_exists($cfgfile)){
    $setting=fopen($cfgfile, "r");
    $ookk="";
    while($ook=fgets($setting)){
      #strip comment
      $commt=strpos($ook,"##");
      if($commt!==false) $ook=substr($ook,0,$commt);
      #append
      if($ook!="") $ookk=$ookk."&".  str_replace($newline,"\n",str_replace("&","%26",trim($ook)));
    }  
    fclose($setting);  
    parse_str($ookk, $setting);
  }
  return $setting;
}
function cfg_save($cfgfile,$setting){
  global $intArray;
  $intArray="";
  for($i=0;$i<2000;$i++)
    $intArray[]=$i;
  if(is_array($setting)){
    $allkeys=array_keys($setting);
    foreach($allkeys as $aKey)
      cfg_recurse($setting[$aKey], $aKey, $outArray);
  }
  $cfgf=fopen($cfgfile,"w");
  foreach($outArray as $aLine)
    fputs($cfgf,stripslashes($aLine)."\r\n");
  fclose($cfgf);
}
function cfg_recurse($stuffIn, $keysofar, &$toAppend){
  global $intArray, $newline;
  if(is_array($stuffIn)){
    $allkeys=array_keys($stuffIn);
    if(array_slice($intArray,0,sizeof($allkeys))==$allkeys)
      $nokey=true;
    else 
      $nokey=false;
    foreach($allkeys as $aKey){
      if(!$nokey) $toKey=$aKey;  
      cfg_recurse($stuffIn[$aKey], $keysofar."[".$toKey."]", $toAppend);
    }
  }else
    $toAppend[]=$keysofar."=".str_replace("\n",$newline,$stuffIn);
}
?>
Note that these functions support nested arrays of unlimited levels ;)

When you have scripts run through the command-line (like locally via cron), you might want to be able to use _GET and _POST vars. Put this in top of your scheduled task files:
<?
  parse_str ($_SERVER['argv'][1], $GLOBALS['_GET']);
  parse_str ($_SERVER['argv'][2], $GLOBALS['_POST']);
?>
And call your script by:
/usr/local/bin/php /path/to/script.php "id=45&action=delete" "formsubmitted=true"
Cheers!

Vladimir Kornea:
Try use html_entity_decode()
$str = 'first=value&amp;arr[]=foo+bar&amp;arr[]=baz';
parse_str(html_entity_decode($str), $output);
print_r($output);
Array
(
  [first] => value
  [arr] => Array
    (
      [0] => foo bar
      [1] => baz
    )
)

I shouldn't've posted the original version, as it only worked with the most basic of query strings.
This function will parse an html-safe query-like url string for variables and php-like ordered and associative arrays. It places them into the global scope as parse_str does and adds minimal slashes for database insertions without the triple-slash problems that magic quotes can produce (the reason I had to write it in the first place). If you don't need the slashes, they're easy enough to remove.
<?php
function parse_query($str) {
  
  // Separate all name-value pairs
  $pairs = explode('&', $str);
  
  foreach($pairs as $pair) {
    
    // Pull out the names and the values
    list($name, $value) = explode('=', $pair, 2);
    
    // Decode the variable name and look for arrays
    list($name, $index) = split('[][]', urldecode($name));
    
    // Arrays
    if(isset($index)) {
      
      // Declare or add to the global array defined by $name
      global $$name;
      if(!isset($$name)) $$name = array();
      
      // Associative array
      if($index != "") {
        ${$name}[$index] = addslashes(urldecode($value));
        
      // Ordered array
      } else {
        array_push($$name, addslashes(urldecode($value)));
      }
    
    // Variables
    } else {
      
      // Declare or overwrite the global variable defined by $name
      global $$name;
      $$name = addslashes(urldecode($value));
    }
  }
}
?>

if you would like to get a nice url scheme with php/apache and and want to handle all requests in a central php script there's a simple solution/hack:
create a .htaccess in your "basedir" where you've got your main script (in this example index.php) containing some lines like:
"ErrorDocument 404 /index.php"
inside index.php you can now do
<?php
  $virtual_path = substr(
    $_SERVER['REQUEST_URI'],
    strlen( dirname( $_SERVER['PHP_SELF'] ) ) + 1
  );
  if( ($pos = strpos( $virtual_path, '?' )) !== false ) {
    parse_str( substr( $virtual_path, $pos + 1 ), $_GET );
    $_REQUEST = array_merge( $_REQUEST, $_GET );
    $virtual_path = substr( $virtual_path, 0, $pos );
  }
  // some code checking for a valid location, etc...
  header( 'HTTP/1.1 200 OK' );
  header( 'Content-Type: text/plain' );
  echo $virtual_path."\n\n";
  print_r( $_REQUEST );
?>
// guido 'lenix' boehm

If you need a function that does something similar to parse_str, but doesn't convert spaces and dots to underscores, try something like the following:
<?php
function parseQueryString($str) {
  $op = array();
  $pairs = explode("&", $str);
  foreach ($pairs as $pair) {
    list($k, $v) = array_map("urldecode", explode("=", $pair));
    $op[$k] = $v;
  }
  return $op;
}
?>
It may need adapting to handle various edge cases.

function like parse_str, but doesn't convert spaces and dots to underscores in $_GET AND $_POST
/**
 * GET and POST input containing dots, etc.
 */
function getRealREQUEST() {
  $vars = array();
  $input  = $_SERVER['REDIRECT_QUERY_STRING'];
  if(!empty($input)){
    $pairs  = explode("&", $input);
    foreach ($pairs   as $pair) {
      $nv        = explode("=", $pair);
      
      $name      = urldecode($nv[0]);
      $nameSanitize  = preg_replace('/([^\[]*)\[.*$/','$1',$name);
      
      $nameMatched  = str_replace('.','_',$nameSanitize);
      $nameMatched  = str_replace(' ','_',$nameMatched);
      
      $vars[$nameSanitize]  = $_REQUEST[$nameMatched];
    }
  }
  
  $input  = file_get_contents("php://input");
  if(!empty($input)){
    $pairs  = explode("&", $input);
    foreach ($pairs as $pair) {
      $nv        = explode("=", $pair);
      
      $name      = urldecode($nv[0]);
      $nameSanitize  = preg_replace('/([^\[]*)\[.*$/','$1',$name);
      
      $nameMatched  = str_replace('.','_',$nameSanitize);
      $nameMatched  = str_replace(' ','_',$nameMatched);
      
      $vars[$nameSanitize]  = $_REQUEST[$nameMatched];
    }
  }
  
  return $vars;
}

This does not work as expected.
<?php
class someclass
{
  var $query_string;
  function someclass($a_query_string)
  {
    $this->query_string = $a_query_string;
    parse_str($this->query_string);
  }
  function output()
  {
    echo $this->action;
  }
}
$a_class = new someclass("action=go");
$a_class->output();
?>
Use this instead.
<?php
class someclass
{
  var $arr;
  function someclass($a_query_string)
  {
    parse_str($a_query_string, $this->arr);
  }
  function output()
  {
    echo $this->arr['action'];
  }
}
$a_class = new someclass("action=go");
$a_class->output();
?>

parse_str() is confused by ampersands (&) being encoded as HTML entities (&amp;). This is relevant if you're extracting your query string from an HTML page (scraping). The solution is to run the string through html_entity_decode() before running it through parse_str().
(Editors: my original comment was a caution whose solution is obvious, but it has resulted in three replies ("so what?" "as intended" and "this is how to fix it"). Please remove the previous four posts dealing with this (69529, 70234, 72745, 74818) and leave just the above summary. This issue is too trivial to warrant the number of comments it has received.)

This function is confused by ampersands (&) being encoded as HTML entities (&amp;).
$str = "first=value&amp;arr[]=foo+bar&amp;arr[]=baz";
parse_str($str, $output);
print_r($output);
Array
(
  [first] => value
  [amp;arr] => Array
    (
      [0] => foo bar
      [1] => baz
    )
)

Beware using parse_str in a function that has vars passed by reference. It seems that parse_str actually creates new vars even if vars of the same name exist. If you pass by ref vars of the same name as those in a query string being parsed new LOCAL vers will be created and you won't get any values passed back to the caller (relates to what Maikel mentioned below)
An unrealistic example (vaguely related to what I was doing when I found this out)...
function get_title($query,&$title)
{
 parse_str($query);
 $title=str_replace("_"," ",$title);
}
$title="foo";
$query = "context=something&title=Title_of_Something";
get_title($query,$title);
echo $title .... "foo"