var_dump
NOTE: If an object Foo has __set_state() method, but if that object contains another object Bar with no __set_state() method implemented, the resulting PHP expression will not be eval()-able.
This is an example (object Test that contains an instance of Exception).
<?php
class Test
{
public $one;
public $two;
public function __construct($one, $two)
{
$this->one = $one;
$this->two = $two;
}
public static function __set_state(array $array)
{
return new self($array['one'], $array['two']);
}
}
$test = new Test('one', new Exception('test'));
$string = var_export($test, true);
/* $string =
Test::__set_state(array(
'one' => 'one',
'two' =>
Exception::__set_state(array(
'message' => 'test',
'string' => '',
'code' => 0,
'file' => 'E:\\xampp\\htdocs\\test.Q.php',
'line' => 35,
'trace' =>
array (
),
'previous' => NULL,
)),
))
*/
eval('$test2 = '.$string.';'); // Fatal error: Call to undefined method Exception::__set_state
?>
So avoid using var_export() on a complex array/object that contains other objects. Instead, use serialize() and unserialize() functions.
<?php
$string = 'unserialize('.var_export(serialize($test), true).')';
eval('$test2 = '.$string.';');
var_dump($test == $test2); // bool(true)
?>
var_export
(PHP 4 >= 4.2.0, PHP 5)
var_export — Retourne le code PHP utilisé pour générer une variable
Description
var_export() retourne des données structurées sur la variable donnée. C'est le même principe que var_dump() mais avec une exception : le résultat retourné est du code PHP valide.
Liste de paramètres
- expression
-
La variable que vous voulez exporter.
- return
-
Si utilisé et mis à TRUE, var_export() retournera la représentation de la variable au lieu de l'afficher.
Note: Cette fonction utilise en interne le buffer de sortie avec ce paramètre, il ne peut donc pas être utilisé dans la fonction de rappel ob_start().
Valeurs de retour
Retourne la représentation de la variable lorsque le paramètre return est utilisé et évalué à TRUE. Autrement, cette fonction retournera NULL.
Historique
| Version | Description |
|---|---|
| 5.1.0 | Possibilité d'exporter des classes et des tableaux contenant des classes en utilisant la méthode magique __set_state. |
Exemples
Exemple #1 Exemple avec var_export()
<?php
$a = array (1, 2, array ("a", "b", "c"));
var_export($a);
?>
L'exemple ci-dessus va afficher :
array (
0 => 1,
1 => 2,
2 =>
array (
0 => 'a',
1 => 'b',
2 => 'c',
),
)
<?php
$b = 3.1;
$v = var_export($b, true);
echo $v; // 3.1
?>
L'exemple ci-dessus va afficher :
3.1
Exemple #2 Exporter des classes depuis PHP 5.1.0
<?php
class A { public $var; }
$a = new A;
$a->var = 5;
var_export($a);
?>
L'exemple ci-dessus va afficher :
A::__set_state(array( 'var' => 5, ))
Exemple #3 Utilisation de __set_state (depuis PHP 5.1.0)
<?php
class A
{
public $var1;
public $var2;
public static function __set_state($an_array)
{
$obj = new A;
$obj->var1 = $an_array['var1'];
$obj->var2 = $an_array['var2'];
return $obj;
}
}
$a = new A;
$a->var1 = 5;
$a->var2 = 'foo';
eval('$b = ' . var_export($a, true) . ';'); // $b = A::__set_state(array(
// 'var1' => 5,
// 'var2' => 'foo',
// ));
var_dump($b);
?>
L'exemple ci-dessus va afficher :
object(A)#2 (2) {
["var1"]=>
int(5)
["var2"]=>
string(3) "foo"
}
Notes
Note: Les variables de type ressource ne peuvent être exportées par cette fonction.
Note: var_export() ne gère pas les références circulaires car il serait impossible de générer un code PHP analysable pour ce type de données. Si vous voulez faire quelque chose avec la représentation complète d'un tableau ou d'un objet, utilisez la fonction serialize().
Voir aussi
- print_r() - Affiche des informations lisibles pour une variable
- serialize() - Linéarise une variable
- var_dump() - Affiche les informations d'une variable
add a note
User Contributed Notesvar_export
rarioj at gmail dot com
29-Oct-2009 06:43
29-Oct-2009 06:43
ravenswd at gmail dot com
07-Jul-2009 05:32
07-Jul-2009 05:32
(This replaces my note of 3-July-2009. The original version produced no output if a variable contained an empty array, or an array consisting only of empty arrays. For example, $bigarray['x'] = array(); Also, I have added a second version of the function.)
The output can be difficult to decipher when looking at an array with many levels and many elements on each level. For example:
<?php
print ('$bigarray = ' . var_export($bigarray, true) . "\n");
?>
will return:
$bigarray = array(
... (500 lines skipped) ...
'mod' => 'charlie',
Whereas the routine below can be called with:
<?php
recursive_print ('$bigarray', $bigarray);
?>
and it will return:
$bigarray = array()
... (500 lines skipped) ...
$bigarray['foo']['bar']['0']['somethingelse']['mod'] = 'charlie'
Here's the function:
<?php
function recursive_print ($varname, $varval) {
if (! is_array($varval)):
print $varname . ' = ' . $varval . "<br>\n";
else:
print $varname . " = array()<br>\n";
foreach ($varval as $key => $val):
recursive_print ($varname . "['" . $key . "']", $val);
endforeach;
endif;
}
?>
For those who want a version that produces valid PHP code, use this version:
<?php
function recursive_print ($varname, $varval) {
if (! is_array($varval)):
print $varname . ' = ' . var_export($varval, true) . ";<br>\n";
else:
print $varname . " = array();<br>\n";
foreach ($varval as $key => $val):
recursive_print ($varname . "[" . var_export($key, true) . "]", $val);
endforeach;
endif;
}
?>
If your output is to a text file and not an HTML page, remove the <br>s.
ravenswd at gmail dot com
03-Jul-2009 12:21
03-Jul-2009 12:21
The output can be difficult to decipher when looking at an array with many levels and many elements on each level. For example:
<?php
print ('$bigarray = ' . var_export($bigarray, true) . "\n");
?>
will return:
$bigarray = array(
... (500 lines skipped) ...
'mod' => 'charlie',
Whereas the routine below can be called with:
<?php
recursive_print ('$bigarray', $bigarray);
?>
and it will return:
$bigarray['firstelement'] = 'something'
... (500 lines skipped) ...
$bigarray['foo']['bar']['0']['somethingelse']['mod'] = 'charlie'
Here's the function:
<?php
function recursive_print ($varname, $varval) {
if (! is_array($varval)):
print $varname . ' = ' . $varval . "<br>\n";
else:
foreach ($varval as $key => $val):
recursive_print ($varname . "['" . $key . "']", $val);
endforeach;
endif;
}
?>
cmusicfan (at) gmail (daught) com
12-Jun-2009 04:19
12-Jun-2009 04:19
Caution! var_export will add a backslash to single quotes (').
You may want to use stripslashes() to remove the mysteriously added backslashes.
stangelanda at arrowquick dot com
29-Jun-2007 11:20
29-Jun-2007 11:20
I have been looking for the best method to store data in cache files.
First, I've identified two limitations of var_export verus serialize. It can't store internal references inside of an array and it can't store a nested object or an array containing objects before PHP 5.1.0.
However, I could deal with both of those so I created a benchmark. I used a single array containing from 10 to 150 indexes. I've generate the elements' values randomly using booleans, nulls, integers, floats, and some nested arrays (the nested arrays are smaller averaging 5 elements but created similarly). The largest percentage of elements are short strings around 10-15 characters. While there is a small number of long strings (around 500 characters).
Benchmarking returned these results for 1000 * [total time] / [iterations (4000 in this case)]
serialize 3.656, 3.575, 3.68, 3.933, mean of 3.71
include 7.099, 5.42, 5.185, 6.076, mean of 5.95
eval 5.514, 5.204, 5.011, 5.788, mean of 5.38
Meaning serialize is around 1 and a half times faster than var_export for a single large array. include and eval were consistently very close but eval was usually a few tenths faster (eval did better this particular set of trials than usual). An opcode cache like APC might make include faster, but otherwise serialize is the best choice.
Glen
24-May-2007 12:47
24-May-2007 12:47
Like previously reported, i find var_export() frustrating when dealing with recursive structures. Doing a :
<?php
var_export($GLOBALS);
?>
fails. Interestingly, var_dump() has some logic to avoid recursive references. So :
<?php
var_dump($GLOBALS);
?>
works (while being more ugly). Unlike var_export(), var_dump() has no option to return the string, so output buffering logic is required if you want to direct the output.
niq
21-Mar-2007 01:44
21-Mar-2007 01:44
To import exported variable you can use this code:
<?
$str=file_get_contents('exported_var.str');
$var=eval('return '.$str.';')
// Now $val contains imported variable
?>
dosperios at dot gmail dot nospam do com
10-Oct-2006 06:19
10-Oct-2006 06:19
Here is a nifty function to export an object with var_export without the keys, which can be useful if you want to export an array but don't want the keys (for example if you want to be able to easily add something in the middle of the array by hand).
<?
function var_export_nokeys ($obj, $ret=false) {
$retval = preg_replace("/'?\w+'?\s+=>\s+/", '', var_export($obj, true));
if ($ret===true) {
return $retval;
} else {
print $retval;
}
}
?>
Works the same as var_export obviously. I found it useful, maybe someone else will too!
nobody at nowhere dot de
30-Aug-2006 10:48
30-Aug-2006 10:48
Here is a bit code, what will read an saved object and turn it into an array.
Please note: It is very lousy style. Only an an idea.
$data = file_get_contents("test.txt");
$data = preg_replace('/class .*{/im', 'array (', $data);
$data = preg_replace('/\}/im', ')', $data);
$data = preg_replace('/var /im', '', $data);
$data = preg_replace('/;/im', ',', $data);
$data = preg_replace('/=/im', '=>', $data);
$data = preg_replace('/=>>/im', '=>', $data);
$data = preg_replace('/\$(.*?) /im', '"$1"', $data);
eval('$O = ' . $data . ';');
print_r($O);
Zorro
05-Sep-2005 06:24
05-Sep-2005 06:24
This function can't export EVERYTHING. Moreover, you can have an error on an simple recursive array:
$test = array();
$test["oops"] = & $test;
echo var_export($test);
=>
Fatal error: Nesting level too deep - recursive dependency? in ??.php on line 59
linus at flowingcreativity dot net
04-Jul-2005 04:50
04-Jul-2005 04:50
<roman at DIESPAM dot feather dot org dot ru>, your function has inefficiencies and problems. I probably speak for everyone when I ask you to test code before you add to the manual.
Since the issue of whitespace only comes up when exporting arrays, you can use the original var_export() for all other variable types. This function does the job, and, from the outside, works the same as var_export().
<?php
function var_export_min($var, $return = false) {
if (is_array($var)) {
$toImplode = array();
foreach ($var as $key => $value) {
$toImplode[] = var_export($key, true).'=>'.var_export_min($value, true);
}
$code = 'array('.implode(',', $toImplode).')';
if ($return) return $code;
else echo $code;
} else {
return var_export($var, $return);
}
}
?>
roman at DIESPAM dot feather dot org dot ru
18-Mar-2005 09:46
18-Mar-2005 09:46
Function that exports variables without adding any junk to the resulting string:
<?php
function encode($var){
if (is_array($var)) {
$code = 'array(';
foreach ($var as $key => $value) {
$code .= "'$key'=>".encode($value).',';
}
$code = chop($code, ','); //remove unnecessary coma
$code .= ')';
return $code;
} else {
if (is_string($var)) {
return "'".$var."'";
} elseif (is_bool($code)) {
return ($code ? 'TRUE' : 'FALSE');
} else {
return 'NULL';
}
}
}
function decode($string){
return eval('return '.$string.';');
}
?>
The resulting string can sometimes be smaller, that output of serialize(). May be useful for storing things in the database.
paul at worldwithoutwalls dot co dot uk
24-Nov-2004 07:22
24-Nov-2004 07:22
var_export() differs from print_r() for variables that are resources, with print_r() being more useful if you are using the function for debugging purposes.
e.g.
<?php
$res = mysql_connect($dbhost, $dbuser, $dbpass);
print_r($res); //output: Resource id #14
var_export($res); //output: NULL
?>
aidan at php dot net
11-Jun-2004 04:53
11-Jun-2004 04:53
This functionality is now implemented in the PEAR package PHP_Compat.
More information about using this function without upgrading your version of PHP can be found on the below link:
http://pear.php.net/package/PHP_Compat
php_manual_note at bigredspark dot com
16-Oct-2003 07:43
16-Oct-2003 07:43
[john holmes]
True, but that method would require you to open and read the file into a variable and then unserialize it into another variable.
Using a file created with var_export() could simply be include()'d, which will be less code and faster.
[kaja]
If you are trying to find a way to temporarily save variables into some other file, check out serialize() and unserialize() instead - this one is more useful for its readable property, very handy while debugging.
[original post]
If you're like me, you're wondering why a function that outputs "correct PHP syntax" is useful. This function can be useful in implementing a cache system. You can var_export() the array into a variable and write it into a file. Writing a string such as
<?php
$string = '<?php $array = ' . $data . '; ?>';
?>
where $data is the output of var_export() can create a file that can be easily include()d back into the script to recreate $array.
The raw output of var_export() could also be eval()d to recreate the array.
---John Holmes...