var_export
(PHP 4 >= 4.2.0, PHP 5)
var_export — Outputs or returns a parsable string representation of a variable
說明
var_export() gets structured information about the given variable. It is similar to var_dump() with one exception: the returned representation is valid PHP code.
參數
- expression
-
The variable you want to export.
- return
-
If used and set to TRUE, var_export() will return the variable representation instead of outputing it.
Note: 該函式的內部依賴這個參數使用輸出緩衝，所以它不能在 ob_start() 的回呼(Callback)函式中使用
Return值
Returns the variable representation when the return parameter is used and evaluates to TRUE. Otherwise, this function will return NULL.
更新日誌
| 版本 | 說明 |
|---|---|
| 5.1.0 | Possibility to export classes and arrays containing classes using the __set_state magic method. |
範例
Example#1 var_export() Examples
<?php
$a = array (1, 2, array ("a", "b", "c"));
var_export($a);
?>
上例將輸出：
array ( 0 => 1, 1 => 2, 2 => array ( 0 => 'a', 1 => 'b', 2 => 'c', ), )
<?php
$b = 3.1;
$v = var_export($b, true);
echo $v;
?>
上例將輸出：
3.1
Example#2 Exporting classes since PHP 5.1.0
<?php
class A { public $var; }
$a = new A;
$a->var = 5;
var_export($a);
?>
上例將輸出：
A::__set_state(array( 'var' => 5, ))
Example#3 Using __set_state (since 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);
?>
上例將輸出：
object(A)#2 (2) { ["var1"]=> int(5) ["var2"]=> string(3) "foo" }
註釋
Note: Variables of type resource couldn't be exported by this function.
Note: var_export() does not handle circular references as it would be close to impossible to generate parsable PHP code for that. If you want to do something with the full representation of an array or object, use serialize().