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extract

(PHP 4, PHP 5)

extractBir dizideki değişkenleri simge tablosuna dahil eder

Açıklama

int extract ( array $dizi [, int $çıkarım_türü = EXTR_OVERWRITE [, string $önek ]] )

Bir dizideki değişkenleri simge tablosuna dahil eder.

Her anahtarın geçerli bir değişken adı olup olmadığına bakmaktan başka bu değişkenlerin simge tablosundakilerle çakışıp çakışmadığına da bakar.

Değiştirgeler

dizi

Bir ilişkisel dizi. Bu işlev anahtarları değişken ismi, değerleri de değişkenin değeri olarak değerlendirir. Her anahtar/değer çifti için simge tablosunda çıkarım_türü ve önek'e uygun bir değişken oluşturulur.

EXTR_PREFIX_ALL veya EXTR_PREFIX_INVALID kullanmadıkça bir sayısal indisli dizi sonuç üretmeyeceğinden bir ilişkisel dizi kullanmanız gerekir.

çıkarım_türü

Geçersiz veya sayısal anahtarların ve çakışmaların ele alınma yöntemini belirtmek için kullanılır. Aşağıdaki değerlerden biri olmalıdır:

EXTR_OVERWRITE
Bir çakışma varsa mevcut değişkenin üzerine yazılır.
EXTR_SKIP
Bir çakışma varsa mevcut değişkenin üzerine yazılmaz.
EXTR_PREFIX_SAME
Bir çakışma varsa değişken isminin başına önek konur.
EXTR_PREFIX_ALL
Tüm değişken isimlerinin başına önek konur.
EXTR_PREFIX_INVALID
Sadece geçersiz veya sayısal indisli değişkerlerin başına önek konur.
EXTR_IF_EXISTS
Sadece simge tablosunda mevcut değişkenlerin üzerine yazılır, bunun dışında bir şey yapılmaz. Geçerli değişkenleri bir liste halinde tanımladıktan sonra bunlardan sadece örneğin $_REQUEST dışında tanımlanmış olanlarını çıkarmak için yararlıdır.
EXTR_PREFIX_IF_EXISTS
Sadece simge tablosunda öneksiz sürümü bulunan değişkenlerin önekli sürümleri oluşturulur.
EXTR_REFS
Değişkenler gönderimli olarak çıkarılır. Dahil edilen değişkenler dizi değerlerine gönderimli iseler bu anlamlıdır. Bu seçeneği tek başına ya da VEYAlamak suretiyle başka bir seçenekle birlikte kullanabilirsiniz.

çıkarım_türü belirtilmezse EXTR_OVERWRITE belirtilmiş sayılır.

önek

Bu değiştirge sadece çıkarım_türü olarak EXTR_PREFIX_SAME, EXTR_PREFIX_ALL, EXTR_PREFIX_INVALID veya EXTR_PREFIX_IF_EXISTS belirtilmişse anlamlıdır. Önekli bir sonuç geçerli bir değişken ismi oluşturmuyorsa simge tablosuna dahil edilmez. Önekler dizi anahtarlarından özdevinimli olarak bir altçizgi karakteri ile ayrılırlar.

Dönen Değerler

Simge tablosuna başarıyla eklenen değişkenlerin sayısı.

Sürüm Bilgisi

Sürüm: Açıklama
4.3.0 EXTR_REFS seçeneği eklendi.
4.2.0 EXTR_IF_EXISTS ve EXTR_PREFIX_IF_EXISTS eklendi.
4.0.5 Dahil edilen değişken sayısını döndürür oldu. EXTR_PREFIX_INVALID eklendi. EXTR_PREFIX_ALL sayısal isimli değişkenleri de içerir oldu.

Örnekler

Örnek 1 - extract() örneği

extract() işlevinin olası kullanımlarınadn biri de wddx_deserialize() tarafından döndürülen ilişkisel dizi içeriğinin simge tablosuna dahil edilmesidir.

<?php

/* Dizinin wddx_deserialize tarafından döndürülen
   bir dizi olduğunu varsayalım */

$boyut "büyük";
$dizi = array("renk"  => "mavi",
              
"boyut" => "orta",
              
"şekil" => "küre");
extract($diziEXTR_PREFIX_SAME"wddx");

echo 
"$renk$boyut$şekil$wddx_boyut\n";

?>

Yukarıdaki örneğin çıktısı:

mavi, büyük, küre, orta

$wddx_boyut değişkeninin oluşturulmasını sağlayan EXTR_PREFIX_SAME seçeneğini belirttiğimizden $boyut değişkeninin üzerine yazılmaz. Eğer seçenek olarak EXTR_SKIP belirtmiş olsaydık $wddx_boyut değişkeni oluşturulmazdı. EXTR_OVERWRITE belirtseydik, $size "orta" değerine sahip olacaktı. Eğer EXTR_PREFIX_ALL belirtmiş olsaydık $wddx_renk, $wddx_boyut ve $wddx_şekil değişkenlerini oluşturmuş olurduk.

Notlar

Uyarı

extract() işlevini kullanıcı girdisi ($_GET, $_FILES, vb.) gibi güvenilmez veriler üzerinde kullanmayın. Aksi takdirde, örneğin, register_globals yönergesinin 'On' olmasını gerektiren eski kodları geçici olarak çalıştırmak isterseniz EXTR_SKIP gibi üste yazmayan çıkarım_türü değerlerini kullanmaya ve php.ini dosyasındaki variables_order yönergesinde tanımlı sırada çıkartmaya çalışın.

Bilginize:

Eğer register_globals yönergesini etkin kılar ve $_FILES üzerinde extract() kullanıp EXTR_SKIP belirtirseniz hiç beklenmedik bir sonuç alabilirsiniz.

Uyarı

Uygulamada bu önerilmez ve bir şeyleri eksik bırakmamak için burada belgelendirmekle yetinilmiştir. Yukarıda belirtildiği gibi, register_globals kullanımı artık önerilmemekte ve $_FILES gibi güvenilir olmayan veriler üzerinde extract() kullanımı olası bir güvenlik riskini beraberinde getirebilir. Böyle bir durumla karşılaşırsanız en azından bu iki kötü kodlama uygulamasından birini kullanıyorsunuz demektir.

<?php

/* Yüklenecek dosyanın ismi $testfile ve
   'register_globals on' olsun. */

var_dump($testfile);
extract($_FILESEXTR_SKIP);
var_dump($testfile);
var_dump($testfile['tmp_name']);

?>
Sonuç olarak şöyle bir şeyler umabiliriz:
string(14) "/tmp/phpgCCPX8"
array(5) {
  ["name"]=>
  string(10) "somefile.txt"
  ["type"]=>
  string(24) "application/octet-stream"
  ["tmp_name"]=>
  string(14) "/tmp/phpgCCPX8"
  ["error"]=>
  int(0)
  ["size"]=>
  int(4208)
}
string(14) "/tmp/phpgCCPX8"
Ancak, bunun yerine aşağıdaki gibi bir şeylaer görürüz:
string(14) "/tmp/phpgCCPX8"
string(14) "/tmp/phpgCCPX8"
string(1) "/"

Bunun sebebi, register_globals 'on' olduğundan dolayı extract() çağrısı yapıldığında $testfile değişkeninin küresel etki alanında mevcut olması ve EXTR_SKIP belirtilmesi nedeniyle $_FILES dizisinin içeriğinin $testfile üzerine yazılmaması, dolayısıyla $testfile'ın bir dizge olarak kalmasıdır. Dizgelere dizi sözdizimi kullanılarak erişilebildiğinden ve sayısal olmayan tmp_name dizgesi 0 olarak yorumlandığından, PHP, $testfile['tmp_name'] ifadesini $testfile[0] olarak görür.

Ayrıca Bakınız

  • compact() - Değişkenlerle değerlerinden oluşan bir dizi oluşturur

add a note add a note

User Contributed Notes 25 notes

up
10
CertaiN
8 months ago
[New Version]

Example Usage:
<?php
$_GET
['A']['a'] = '  CORRECT(including some spaces)    ';
$_GET['A']['b'] = '  CORRECT(including some spaces)    ';
$_GET['A']['c'] = "Invalid UTF-8 sequence: \xe3\xe3\xe3";
$_GET['A']['d']['invalid_structure'] = 'INVALID';

$_GET['B']['a'] = '  CORRECT(including some spaces)    ';
$_GET['B']['b'] = "Invalid UTF-8 sequence: \xe3\xe3\xe3";
$_GET['B']['c']['invalid_structure'] = 'INVALID';
$_GET['B']["Invalid UTF-8 sequence: \xe3\xe3\xe3"] = 'INVALID';

$_GET['C']['a'] = '  CORRECT(including some spaces)    ';
$_GET['C']['b'] = "Invalid UTF-8 sequence: \xe3\xe3\xe3";
$_GET['C']['c']['invalid_structure'] = 'INVALID';
$_GET['C']["Invalid UTF-8 sequence: \xe3\xe3\xe3"] = 'INVALID';

$_GET['unneeded_item'] = 'UNNEEDED';

var_dump(filter_struct_utf8(INPUT_GET, array(
   
'A' => array(
       
'a' => '',
       
'b' => FILTER_STRUCT_TRIM,
       
'c' => '',
       
'd' => '',
    ),
   
'B' => FILTER_STRUCT_FORCE_ARRAY,
   
'C' => FILTER_STRUCT_FORCE_ARRAY | FILTER_STRUCT_TRIM,
)));
?>

Example Result:
array(3) {
  ["A"]=>
  array(4) {
    ["a"]=>
    string(36) "  CORRECT(including some spaces)    "
    ["b"]=>
    string(30) "CORRECT(including some spaces)"
    ["c"]=>
    string(0) ""
    ["d"]=>
    string(0) ""
  }
  ["B"]=>
  array(3) {
    ["a"]=>
    string(36) "  CORRECT(including some spaces)    "
    ["b"]=>
    string(0) ""
    ["c"]=>
    string(0) ""
  }
  ["C"]=>
  array(3) {
    ["a"]=>
    string(30) "CORRECT(including some spaces)"
    ["b"]=>
    string(0) ""
    ["c"]=>
    string(0) ""
  }
}
up
6
Dan O'Donnell
7 years ago
Following up on ktwombley at gmail dot com's post:

Presumably one easy way of dealing with this security issue is to use the EXTR_IF_EXISTS flag and make sure

a) your define acceptable input variables beforehand (i.e. as empty variables)
b) Sanitise any user input to avoid unacceptable variable content.

If you do these two things, then I'm not sure I see the difference between extract($_REQUEST,EXTR_IF_EXISTS); and assigning each of the variables by hand.

I'm not talking here about the idea of storing the variables in a database, just the immediately necessary steps to allow you to use extract on REQUEST arrays with relative safety.
up
5
dotslash.lu at gmail.com
1 year ago
You can't extract a numeric indexed array(e.g. non-assoc array).
<?php
$a
= array(
 
1,
 
2
);
extract($a);
var_dump(${1});
?>

result:
PHP Notice:  Undefined variable: 1 in /Users/Lutashi/t.php on line 7

Notice: Undefined variable: 1 in /Users/Lutashi/t.php on line 7
NULL
up
6
CertaiN
8 months ago
[New Version]
This function is very useful for filtering complicated array structure.
Also, Some integer bitmasks and invalid UTF-8 sequence detection are available.

Code:
<?php
/**
* @param  integer $type    Constant like INPUT_XXX.
* @param  array   $default Default structure of the specified super global var.
*                          Following bitmasks are available:
*  + FILTER_STRUCT_FORCE_ARRAY - Force 1 dimensional array.
*  + FILTER_STRUCT_TRIM        - Trim by ASCII control chars.
*  + FILTER_STRUCT_FULL_TRIM   - Trim by ASCII control chars,
*                                full-width and no-break space.
* @return array            The value of the filtered super global var.
*/
define('FILTER_STRUCT_FORCE_ARRAY', 1);
define('FILTER_STRUCT_TRIM', 2);
define('FILTER_STRUCT_FULL_TRIM', 4);
function
filter_struct_utf8($type, array $default) {
    static
$func = __FUNCTION__;
    static
$trim = "[\\x0-\x20\x7f]";
    static
$ftrim = "[\\x0-\x20\x7f\xc2\xa0\xe3\x80\x80]";
    static
$recursive_static = false;
    if (!
$recursive = $recursive_static) {
       
$types = array(
           
INPUT_GET => $_GET,
           
INPUT_POST => $_POST,
           
INPUT_COOKIE => $_COOKIE,
           
INPUT_REQUEST => $_REQUEST,
        );
        if (!isset(
$types[(int)$type])) {
            throw new
LogicException('unknown super global var type');
        }
       
$var = $types[(int)$type];
       
$recursive_static = true;
    } else {
       
$var = $type;
    }
   
$ret = array();
    foreach (
$default as $key => $value) {
        if (
$is_int = is_int($value)) {
            if (!(
$value | (
               
FILTER_STRUCT_FORCE_ARRAY |
               
FILTER_STRUCT_FULL_TRIM |
               
FILTER_STRUCT_TRIM
           
))) {
               
$recursive_static = false;
                throw new
LogicException('unknown bitmask');
            }
            if (
$value & FILTER_STRUCT_FORCE_ARRAY) {
               
$tmp = array();
                if (isset(
$var[$key])) {
                    foreach ((array)
$var[$key] as $k => $v) {
                        if (!
preg_match('//u', $k)){
                            continue;
                        }
                       
$value &= FILTER_STRUCT_FULL_TRIM | FILTER_STRUCT_TRIM;
                       
$tmp += array($k => $value ? $value : '');
                    }
                }
               
$value = $tmp;
            }
        }
        if (
$isset = isset($var[$key]) and is_array($value)) {
           
$ret[$key] = $func($var[$key], $value);
        } elseif (!
$isset || is_array($var[$key])) {
           
$ret[$key] = null;
        } elseif (
$is_int && $value & FILTER_STRUCT_FULL_TRIM) {
           
$ret[$key] = preg_replace("/\A{$ftrim}++|{$ftrim}++\z/u", '', $var[$key]);
        } elseif (
$is_int && $value & FILTER_STRUCT_TRIM) {
           
$ret[$key] = preg_replace("/\A{$trim}++|{$trim}++\z/u", '', $var[$key]);
        } else {
           
$ret[$key] = preg_replace('//u', '', $var[$key]);
        }
        if (
$ret[$key] === null) {
           
$ret[$key] = $is_int ? '' : $value;
        }
    }
    if (!
$recursive) {
       
$recursive_static = false;
    }
    return
$ret;
}
?>
up
6
Robc
2 years ago
When extracting from a row after a database query using for example:

$row = mysql_fetch_array($result, MYSQL_ASSOC)
extract($row);

I find that the resultant variables may not match the variable type in the database.  In particular I have found integers in the database may gettype() to string on the extracted variable.
up
4
Michael Newton
9 years ago
They say "If the result is not a valid variable name, it is not imported into the symbol table."

What they should say is that if _any_ of the results have invalid names, _none_ of the variables get extracted.

Under 4.3.10 on Windows 2000, I was pulling some mySQL records, but needed to convert two fields into IP addresses:
<?
extract(mysql_fetch_assoc(mysql_query('SELECT * FROM foo')));
extract(mysql_fetch_assoc(mysql_query('SELECT INET_NTOA(bar) AS bar, INET_NTOA(baz) FROM foo')));
?>

I had forgotten the second AS modifier in the SQL query.  Because it couldn't extract a variable called INET_NTOA(baz) into the symbol table, it didn't do either of them.

(BTW I don't normally stack functions up like that!  Just to make a short example!)
up
2
anon at anon dot org
9 years ago
A warning about extract() and null values.

This might be an actual Zend2 Engine bug, but it's bad programming practice, so I'm sharing it here instead.

I often work in envrionments where E_STRICT (which would prevent errors like this) isn't on, and I don't have access to change it. I also use a very simple template class that in a nutshell works like this:

$t = new Template('somefile.php');
$t->title = $title;
$t->body = $body;
$t->display();

display() more or less looks like this:

function display(){
    extract(get_object_vars($this),EXTR_REFS);
    ob_start(); include $this->templateFileName;
    return ob_get_clean();
}

If any of the assigned values are null (let's say that in this case $title wasn't initialized above) it causes the engine to do all sorts of incredibly whacky stuff like certifiably lose track of variables in an incredibly inconsistent way. I traced the problem down to the fact that it's using the EXTR_REFS flag. I assume that in PHP's internal variable storage or reference counting mechanism, that trying to extract null references makes it lose track or count of something or rather.

In a nutshell, if you start getting wierd behavior when using extract() make sure that the array or object you are trying to get variables out of doesn't contain null keys or values!
up
3
ktwombley at gmail dot com
8 years ago
It's really easy to open gaping security holes using extract() on $_REQUEST, $_GET, etc. You have to be really sure of what you're doing, and use the proper flags on extract() to avoid clobbering important variables.

For instance, the submission by kake26 at gmail dot com will not only perfectly emulate register globals (that's bad), but it'll store it in a database and recall the same variables every time the script runs (essentially allowing an attacker to attack your script every time it runs via one attack). Oops!

To fix it, you'd have to get creative with flags. Maybe you could use EXTR_PREFIX_ALL instead of EXTR_OVERWRITE, for example. Of course, you should also sanitize the form elements to ensure there's no php code in them, and also to make sure any very important variables aren't in the form data. (like the classic $is_admin = true attack)
up
2
Csaba at alum dot mit dot edu
8 years ago
Sometimes you may want to extract only a named subset of the key/value pairs in an array.  This keeps things more orderly and could prevent an unrelated variable from getting clobbered from an errant key.  For example,

$things = 'unsaid';
$REQUEST = array(He=>This, said=>1, my=>is, info=>2, had=>a,
                 very=>3, important=>test, things=>4);
$aVarToExtract = array(my, important, info);
extract (array_intersect_key ($REQUEST, array_flip($aVarToExtract)));

will extract
$my = 'is';
$important = 'test';
$info = 2;

but will leave certain
$things = 'unsaid'

Csaba Gabor from Vienna
NB.  Of course the composite request coming in from a web page is in $_REQUEST.
up
1
benjaminATwebbutvecklarnaDOTse
6 years ago
Re: anon at anon dot org, about extract() and null values

Personally I've found use extracting multiple resultsets from db where the latter would overwrite the previous when a variable is not null ( and optionally if its not >0 )

It would be useful if $extract_type was extended on top of these two:

EXTR_OVERWRITE
EXTR_SKIP

with something like this:

EXTR_OVERWRITE_NULL
- If there is a collision, overwrite the existing variable if it is null

EXTR_OVERWRITE_0
- Same thing but == 0 or null

EXTR_SKIP_NULL
- If there is a collision, skip the new variable if the existing is not null

EXTR_SKIP_0
- Same thing but == 0 or null

Those ought to cover a few good cases that aren't covered now.
up
0
FredLawl
1 year ago
It is possible to use this as a way to create public attributes for a class.

<?php
class Foo {

  public function
__construct ($array) {

     
extract($array, EXTR_REFS);
      foreach (
$array as $key => $value) {
         
$this->$key = $$key;
         
// Do: $this->key = $key; if $key is not a string.
     
}

  }

}

$array = array(
   
'valueOne'      => 'Test Value 1',
   
'valueTwo'      => 'Test Value 2',
   
'valueThree'    => 'Test Value 3'
);

$foo = new Foo($array);

// Works
echo $foo->valueOne; // Test Value 1
echo $foo->valueTwo; // Test Value 2

// Does not work!
echo $foo::$valueOne; // Fatal error:  Access to undeclared static property: Test::$valueOne
?>
up
0
auto493097 at hushmail dot com
4 years ago
I use XDebug with NetbeansIDE to for analyzing and developing PHP Code. When debugging an extract statement no new variables appeared in the variable's list. Although all variables created by extract could be examined by explicit watch items and single variables appeared as soon as an PHP script makes use of them I am not sure weather it is a wrong configuration, a feature or a bug in XDebug.
up
0
Hayley Watson
6 years ago
Dan O'Donnell's suggestion needs a third requirement to work as described:

c) No other variables are defined - especially variables that contain potentially sensitive information.

Without that condition the difference between extract() and assigning variables by hand (and the resulting security implications) should be obvious.

The only valid security step there is (b) - but you should be doing that anyway.
up
0
Dutchdavey
7 years ago
I would draw your attention to the user note at the very end of this page regarding PREFIXES. The user points out that php adds a '_' to your prefixes.
up
0
nicolas zeh
8 years ago
This function provides exactly the same functionality as extract except that a parameter was added defining the extract target.
This function can be used if your PHP installation does not support the required Flags or more important if you would like to extract arrays to another destination as to $GLOBALS, i.e. other arrays or objects.
The only difference to extract is that extract_to moves the array pointer of $arr to the end as $arr is passed by reference to support the EXTR_REFS flag.

<?php
   
if( !defined('EXTR_PREFIX_ALL') ) define('EXTR_PREFIX_ALL', 3);
    if( !
defined('EXTR_PREFIX_INVALID') ) define('EXTR_PREFIX_INVALID', 4);
    if( !
defined('EXTR_IF_EXISTS') ) define('EXTR_IF_EXISTS', 5);
    if( !
defined('EXTR_PREFIX_IF_EXISTS') ) define('EXTR_PREFIX_IF_EXISTS', 6);
    if( !
defined('EXTR_REFS') ) define('EXTR_REFS', 256);
   
   
    function
extract_to( &$arr, &$to, $type=EXTR_OVERWRITE, $prefix=false ){
       
        if( !
is_array( $arr ) ) return trigger_error("extract_to(): First argument should be an array", E_USER_WARNING );
       
        if(
is_array( $to ) ) $t=0;
        else if(
is_object( $to ) ) $t=1;
        else return
trigger_error("extract_to(): Second argument should be an array or object", E_USER_WARNING );
       
        if(
$type==EXTR_PREFIX_SAME || $type==EXTR_PREFIX_ALL || $type==EXTR_PREFIX_INVALID || $type==EXTR_PREFIX_IF_EXISTS )
            if(
$prefix===false ) return trigger_error("extract_to(): Prefix expected to be specified", E_USER_WARNING );
            else
$prefix .= '_';
       
       
$i=0;
        foreach(
$arr as $key=>$val ){
           
           
$nkey = $key;
           
$isset = $t==1 ? isset( $to[$key] ) : isset( $to->$key );
           
            if( (
$type==EXTR_SKIP && $isset )
                || (
$type==EXTR_IF_EXISTS && !$isset ) )
                    continue;
           
            else if( (
$type==EXTR_PREFIX_SAME && $isset )
                || (
$type==EXTR_PREFIX_ALL )
                || (
$type==EXTR_PREFIX_INVALID && !preg_match( '#^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$#', $key ) ) )
                   
$nkey = $prefix.$key;
                   
            else if(
$type==EXTR_PREFIX_IF_EXISTS )
                if(
$isset ) $nkey = $prefix.$key;
                else continue;

            if( !
preg_match( '#^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$#', $nkey ) ) continue;
           
            if(
$t==1 )
                if(
$type & EXTR_REFS ) $to->$nkey = &$arr[$key];
                else
$to->$nkey = $val;
            else
                if(
$type & EXTR_REFS ) $to[$nkey] = &$arr[$key];
                else
$to[$nkey] = $val;
           
           
$i++;
        }
       
        return
$i;
    }
   
   
// e.g.:
   
extract_to( $myarray, $myobject, EXTR_IF_EXISTS );
?>
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0
owk dot ch199_ph at gadz dot org
8 years ago
And if you want with PHP 5 an easy way to extract $V by reference, try this :
<?php
   
foreach ($V as $k => &$v) {
        $
$k =& $v;
    }
?>
It can be used to create special kind of "free args" functions that let you choose when you call them the way you send variables, and which ones. They are moreover very fast to call thanks to references :
<?php
   
function free_args (&$V) {
        foreach (
$V as $k => &$v) {
            $
$k =& $v;
        }
        unset (
$k);  unset ($v);  unset ($V);

       
// be careful that if you need to extract $k, $v or $V variables you should find other names for them in the lines above (ie. $__k, $__v and $__V)
   
}

   
$huge_text = '...';

   
$a = array ('arg1' => 'val1', 'arg2' => &$huge_text); // in this call, only $arg2 will be a true reference in the function
   
free_args ($a);
?>
Be warned that you can't write : "<?php free_args (array ('arg1' => 'val1')); ?>" because the array can't be referenced by the function, as it's not yet created when the function starts.
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0
moslehi<atsign>gmail<d0t>c0m
8 years ago
Experimentally I found that calling extract() also shows the number of keys if the key is set and is not numeric ! Maybe there was a better definition than mine  . Please have a look to this scripts :

<?PHP
$var
["i"] = "a";
$var["j"] = "b";
$var["k"] = 1;
echo
extract($var); // returns 3
?>

<?PHP
$var2
["i"] = "a";
$var2[2] = "b";
$var2[] = 1;
echo
extract($var2); // returns 1
?>

(Arash Moslehi)
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0
pg dot perfection at gmail dot com
9 years ago
Here is a little example of how an extraction method should look like when it needs to work recursive (work on nested_arrays too)...

Note that this is only an example, it can be done more easily, and more advanced too.

<?php
/**
* A nested version of the extract () function.
*
* @param    array    $array        The array which to extract the variables from
* @param    int        $type        The type to use to overwrite (follows the same as extract () on PHP 5.0.3
* @param    string    $prefix        The prefix to be used for a variable when necessary
*/
function extract_nested (&$array, $type = EXTR_OVERWRITE, $prefix = '')
{
   
/**
     *  Is the array really an array?
     */
   
if (!is_array ($array))
    {
        return
trigger_error ('extract_nested (): First argument should be an array', E_USER_WARNING);
    }

   
/**
     *  If the prefix is set, check if the prefix matches an acceptable regex pattern
     * (the one used for variables)
     */
   
if (!empty ($prefix) && !preg_match ('#^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$#', $prefix))
    {
        return
trigger_error ('extract_nested (): Third argument should start with a letter or an underscore', E_USER_WARNING);
    }

   
/**
     * Check if a prefix is necessary. If so and it is empty return an error.
     */
   
if (($type == EXTR_PREFIX_SAME || $type == EXTR_PREFIX_ALL || $type == EXTR_PREFIX_IF_EXISTS) && empty ($prefix))
    {
        return
trigger_error ('extract_nested (): Prefix expected to be specified', E_USER_WARNING);
    }

   
/**
     * Make sure the prefix is oke
     */
   
$prefix = $prefix . '_';

   
/**
     *  Loop thru the array
     */
   
foreach ($array as $key => $val)
    {
       
/**
         *  If the key isn't an array extract it as we need to do
         */
       
if (!is_array ($array[$key]))
        {
            switch (
$type)
            {
                default:
                case
EXTR_OVERWRITE:
                   
$GLOBALS[$key] = $val;
                break;
                case
EXTR_SKIP:
                   
$GLOBALS[$key] = isset ($GLOBALS[$key]) ? $GLOBALS[$key] : $val;
                break;
                case
EXTR_PREFIX_SAME:
                    if (isset (
$GLOBALS[$key]))
                    {
                       
$GLOBALS[$prefix . $key] = $val;
                    }
                    else
                    {
                       
$GLOBALS[$key] = $val;
                    }
                break;
                case
EXTR_PREFIX_ALL:
                   
$GLOBALS[$prefix . $key] = $val;
                break;
                case
EXTR_PREFIX_INVALID:
                    if (!
preg_match ('#^[a-zA-Z_\x7f-\xff]$#', $key{0}))
                    {
                       
$GLOBALS[$prefix . $key] = $val;
                    }
                    else
                    {
                       
$GLOBALS[$key] = $val;
                    }
                break;
                case
EXTR_IF_EXISTS:
                    if (isset (
$GLOBALS[$key]))
                    {
                       
$GLOBALS[$key] = $val;
                    }
                break;
                case
EXTR_PREFIX_IF_EXISTS:
                    if (isset (
$GLOBALS[$key]))
                    {
                       
$GLOBALS[$prefix . $key] = $val;
                    }
                break;
                case
EXTR_REFS:
                   
$GLOBALS[$key] =& $array[$key];
                break;
            }
        }
       
/**
         *  The key is an array... use the function on that index
         */
       
else
        {
           
extract_nested ($array[$key], $type, $prefix);
        }
    }
}
?>
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0
Anonymous
9 years ago
To make this perfectly clear (hopefully), an underscore is always added when the string is prefixed.
extract(array("color" => "blue"),EXTR_PREFIX_ALL,'');// note: prefix is empty
is the same as
$color='_blue';
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0
Aaron Stone
9 years ago
If you are working porting an older application, and taking the advice above, extracting only _SERVER, _SESSING, _COOKIE, _POST, _GET, you have forgotten to extract _FILES. Putting _FILES last and using EXTR_SKIP doesn't work because the name of the file upload box is already set as a variable containing only the temporary name of the uploaded file from one of the earlier extracts (I haven't tested to see which one specifically, however). A workaround is to put _FILES last and use EXTR_OVERWRITE. This allows extract to replace that temp-name-only variable with the full array of file upload information.
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0
Adam Monsen <adamm at wazamatta dot com>
9 years ago
As shown in the example, if your 'prefix' is used, a single underscore is added to the name of the extracted variable. Meaning, a prefix of 'p' becomes a prefix of 'p_', so 'blarg' prefixed would be 'p_blarg'.

If you're not sure what variables you've created through extraction, you can call get_defined_vars() to see all defined variables in the current scope.
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-1
danbettles at yahoo dot co dot uk
5 years ago
When using EXTR_PREFIX_ALL - and probably all the other EXTR_PREFIX_* constants - and a numerically-indexed array, extract() will add an underscore ("_") between the prefix and the index.

<?php

extract
(array('foo', 'bar'), EXTR_PREFIX_ALL, 'var');

print_r(get_defined_vars());  // Reveals $var_0 = 'foo' and $var_1 = 'bar'
?>
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-1
benjaminATwebbutvecklarnaDOTse
6 years ago
In the meantime, I'm using this:

// extract alternative
# extracts variables where new value is above the threshold or if old value is on or below the threshold (or var is not defined)
# an associative array is obviously the sane thing to pass
#
# I am absolutely certain someone will find obvious problems or errors with this
# I haven't even tried to compare other values than 0 so if you need to do that and surely finds obvious flaws,
# please mail me, I'd really like to know.
# benjaminATwebbutvecklarnaDOTse

// usage example:
# thrextract(mysql_fetch_assoc(mysql_query("SELECT preset_this,preset_that FROM site_preset WHERE ID = $site_id")));
# thrextract(mysql_fetch_assoc(mysql_query("SELECT preset_this,preset_that FROM category_preset WHERE ID = $category_id")));

function thrextract($arr,$thr = 0){
    foreach($arr as $key => $var){
        global $$key;
        if($var > $thr or $$key <= $thr) $$key = $var;
    }
}
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-3
Rodrigo
4 years ago
Here's a way to use extract in $_FILES arrays without using register_gloabals on.

I started to use extract a few weeks ago, and my codes hasn't been so clean since then. The use of the arrays $_POST and $_GET is ok, but one missed doublequote causes a lot of trouble.

Besides I teach PHP in a school, and this function has made my examples easier.

<?php
if(isset($_FILES["file"])){
   
extract($_FILES);
   
extract($file);
    echo
$name."<br>";
    echo
$tmp_name."<br>";
    echo
$size."<br>";
}
?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Documento sin t&iacute;tulo</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>

<body>
<form action="" method="post" enctype="multipart/form-data" name="form1">
  <p>
    <input type="file" name="file">
</p>
  <p>
    <input type="submit" name="Submit" value="Enviar">
</p>
</form>
</body>
</html>

Hope this can help anyone.
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-5
kake26 at gmail dot com
9 years ago
The following is a neat use for extract to store and manipulate large amounts of form data from. I basically loop through the $_POST and implode it seperating the key and value pairs by a space. Then store it in a db, the reversing function basically explodes the string to a array. Then converts the indexed array to a associative array then uses extract to seal the deal and make it easily available within a program. My main reason for sharing these are the fact I make some big web applications that store allot of forum data in a DB and these functions make it very easy to quickly and easily store and recall the data. I've contributed it because I spent many hours creating this code and recall going "I wish someone had previously submitted it to the page notes". Would have saved me allot of time and agony and I'm sure I'm not the only person that could really benefit from it, so I decided to share.

<?php
$stack
= array();
foreach (
$_POST as $key => $value) {
array_push($stack, $key, $value);
}
// store it
$block = implode(" ",$stack); // yeilds a space delimited string
// insert query to store string in DB here, like the one below
$query = "INSERT INTO `sometable` VALUES('".$seluser."','".addslashes($block)."');";
$result = mysql_query($query) or die("Query failed for block insert: " . mysql_error());
// note $seluser in my case is a user ID associated with that block
// in one of my web apps
?>

The nice thing is with the above we can quickly create a string of key and value pairs from the data the script got. Without really caring what their names are. You know how if register globals are on you say $someformvar rather than $_POST["someformvar"]; , basically the code below reads this previous created block returns it to that state. Sort of like presistant register globals.

<?php
// insert query to grab the previously stored string here
$query = "SELECT * FROM `sometable` WHERE `blockid` = '".addslashes($bid)."';";
$result = mysql_query($query) or die("Query failed read: " . mysql_error());
$sql = mysql_fetch_array($result, MYSQL_ASSOC);
$array = eplode(" ",$sql["data"]);
for (
$i = 0; $i < sizeof($array); $i+=2) {
$myassoc[$array[$i]] = isset($array[$i+1])?$array[$i+1]:NULL;
}
extract($myassoc, EXTR_OVERWRITE);
// now you're key and value pairs from $_POST have been restored
// instead of $_POST
?>
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