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PHP : Function Reference : String Functions : parse_str

parse_str

Parses the string into variables (PHP 4, PHP 5)
void parse_str ( string str [, array &arr] )

Parses str as if it were the query string passed via a URL and sets variables in the current scope.

Note:

To get the current QUERY_STRING, you may use the variable $_SERVER['QUERY_STRING']. Also, you may want to read the section on variables from outside of PHP.

Note:

The magic_quotes_gpc setting affects the output of this function, as parse_str() uses the same mechanism that PHP uses to populate the $_GET, $_POST, etc. variables.

Parameters

str

The input string.

arr

If the second parameter arr is present, variables are stored in this variable as array elements instead.

Return Values

No value is returned.

ChangeLog

Version Description
4.0.3 The arr parameter was added

Examples

Example2425.Using parse_str()

<?php
$str
= "first=value&arr[]=foo+bar&arr[]=baz";
parse_str($str);
echo
$first; // value
echo $arr[0]; // foo bar
echo $arr[1]; // baz

parse_str($str, $output);
echo
$output['first']; // value
echo $output['arr'][0]; // foo bar
echo $output['arr'][1]; // baz

?>


Code Examples / Notes » parse_str

kent

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;
}
?>


dante

You can perform the opposite of this function if you like with a function like I've built below:
   /**
    * Reverse of parse_str().  Converts array into
    * string with query format
    */
   function query_str ($params) {
       $str = '';
       foreach ($params as $key => $value) {
           $str .= (strlen($str) < 1) ? '' : '&';
           $str .= $key . '=' . rawurlencode($value);
       }
       return ($str);
   }
-- Dante


11-mar-2005 12:26

yet another simpler way to do the reverse this function.
<?php
/* BSD LINCENSE */
function build_str($query_array) {
$query_string = array();
foreach ($query_array as $k => $v) {
$query_string[] = $k.'='.$v;
}
return join('&', $query_string);
}
// example of use
// set  a query string
$test_query = "a=b&c=d";
// parse a string
parse_str($test_query, $query_array);
//print it
print_r($query_array);

// test the build_str function
if ( build_str($query_array) == $test_query ) {
echo "It works";
} else {
echo "It doesn't work";
}
?>


motin

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!


olivier mengué

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.


michal zalewski

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
       )
)


jgbreezer

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).


php

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

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
       )
)


kerosuppi

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();
?>


vargasangelo_1990

this can be another option for STR PARSING and use it as a $_GET variable.
<?php
$str= "op=downloads&id=1&details=1";
function parse_to_get($str=false){
if($REQUEST_URI==$str): $ex = explode("/".$PHP_SELF."?", $str); $str = $ex[1]; endif;
if($str):
$a = explode("&", $str);
foreach($a as $e){
if($e):
list($k,$v)=explode("=", $e);
$_GET[$k]=$v;
endif;
}
endif;
extract($_GET);
}
parse_top_get("index.php?page=info&name=jonh&id=4245&app=server");
?>
:)
//Trukin


31-mar-2004 07:58

The documentation does not appear to mention that parse_str also urldecodes each item in the resulting array.
There also appears to be a bug in earlier versions of PHP that causes these urldecoded strings to also be escaped.  (Certainly I was having problems with %22 being turned into /" on my server, but not on my development box, despite forcing magic quotes off).


vladimir kornea

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.)


17-jun-2004 01:23

Note that variables cannot contain a DOT (.) in PHP. So, DOT will be replaced by underscore.
e.g. variables like "variable.something" will be converted into "variable_something".


nospam

Maybe you need an opposite which works with arrays:
<?php
function query_str ($params) {
if ( !is_array($params) || count($params) == 0 ) return false;
$fga = func_get_args();
$akey = ( !isset($fga[1]) ) ? false : $fga[1];
static $out = Array();

foreach ( $params as $key=>$val ) {
if ( is_array($val) ) {
query_str($val,$key);
continue;
}
$thekey = ( !$akey ) ? $key : $akey.'['.$key.']';
$out[] = $thekey."=".$val;
}

return implode("&",$out);
}
?>


evan k

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']);
?>


et

In reply to what kerosuppi posted:
[quote]This does not work as expected.[/quote]
No, it works exactly as expected.
The call <?php parse_str($this->query_string);?>  "sets variables in the current scope" (just like said in the manual).
You are using this call in the constructor. Once the constructor is finished, the scope of this function has ended so it's logical that you can't access the variables anymore.
Your workaround though is a good one.
Hope this helps,
ET


mortoray

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.

lenix.de

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


chris

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;
}
}
?>


avi

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.

matt curtis

If the querystring contains duplicate keys in the key-value pairs, parse_str will only return the last instance of the value.  For example, in the following:
<?php
$mystr = "test1=blah&test2=bleh&test1=burp";
parse_str($mystr, $myarray);
echo $myarray['test1'];
?>
The value output will be 'burp'.  
I wrote a function that takes a querystring and returns the the key-value pairs as a two-dimensional array so each duplicate key is available:
<?php
$str = "test1=blah&test2=bleh&test1=burp";
$valsarray = parse_str_ext($str);
echo $valsarray['test1'][0];
echo $valsarray['test1'][1];
echo $valsarray['test2'][0];
function parse_str_ext($toparse) {
$returnarray = array();
$keyvaluepairs = split("&", $toparse);
foreach($keyvaluepairs as $pairval) {
$splitpair = split("=", $pairval);
if(!array_key_exists($splitpair[0], $returnarray)) $returnarray[$splitpair[0]] = array();
$returnarray[$splitpair[0]][] = $splitpair[1];
}
return $returnarray;
}
?>
Output will be:
blah
burp
bleh


anatilmizun

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 ;)


miket3

I saw some posts with people wondering
why &'s are being
sent to this function.  Well, basically
because thats what comes
from a QUERY_STRING. Anyway. The bug i found is
that the first part of a query_string
may not contain an &. Usually the
first parameter comes directly after the ?.
So you
might have to manually pre-pend an & to your
query_string if one does not exist.
<?php
$base="www.yahoo.com/search.aspx?";
$parsedurl=parse_url($base."&".rawurldecode($_SERVER
['QUERY_STRING']), PHP_URL_QUERY);
parse_str($parsedurl,$myquery);
$qbn = "n=".urlencode($myquery['n']);
?>
oh my god! to get this to post is ridiculous.


arjan

http_build_query() does that too.

mike dot coley

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.


pepe_rivas

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
?>


tore bjølseth

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 "
url1: ".$url1;
echo "
url2: ".$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.)


kermodebear

An old post from several years ago mentions that variable names cannot have a dot. They also cannot have a space. Spaces are automatically replaced with an underscore.
The following:
parse_str("My Value=Something", $result);
Will result in:
$result['My_Value'] = 'Something'
Although I understand why it is done, I still feel that this is unintuitive behavior.


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