PHP - Manual: current

2024-11-15

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current

(PHP 4, PHP 5, PHP 7, PHP 8)

current — 返回数组中的当前值

说明

current(array|object $array): mixed

每个数组中都有一个内部的指针指向它“当前的”单元，初始化时会指向该数组中的第一个值。

参数

array: 要操作的数组。

返回值

current() 函数返回当前被内部指针指向的数组单元的值，并不移动指针。如果内部指针指向超出了单元列表的末端，current() 将返回 false。

警告

此函数可能返回布尔值 false，但也可能返回等同于 false 的非布尔值。请阅读布尔类型章节以获取更多信息。应使用 === 运算符来测试此函数的返回值。

更新日志

版本	说明
8.1.0	弃用在 object 上调用此函数。在 object 优先使用 get_mangled_object_vars() 或者使用 ArrayIterator。

范例

示例 #1 current() 函数使用示例


<?php
$transport = array('foot', 'bike', 'car', 'plane');
$mode = current($transport); // $mode = 'foot';
$mode = next($transport);    // $mode = 'bike';
$mode = current($transport); // $mode = 'bike';
$mode = prev($transport);    // $mode = 'foot';
$mode = end($transport);     // $mode = 'plane';
$mode = current($transport); // $mode = 'plane';

$arr = array();
var_dump(current($arr)); // bool(false)

$arr = array(array());
var_dump(current($arr)); // array(0) { }
?>

注释

注意: 在一个空数组上使用 current() 函数，和在一个内部指针指向单元末端以外的数组上使用此函数，结果是相同的，同样都会返回 bool false。如果希望正确遍历一个包含 false 的数组，请参阅 foreach 控制结构。如果仍然希望使用 current() 来判断数组单元真实的值，应该同时使用 key() 和 current() 来检查当前元素是否为 null。

参见

end() - 将数组的内部指针指向最后一个单元
key() - 从关联数组中取得键名
each() - 返回数组中当前的键／值对并将数组指针向前移动一步
prev() - 将数组的内部指针倒回一位
reset() - 将数组的内部指针指向第一个单元
next() - 将数组中的内部指针向前移动一位
foreach

add a note

User Contributed Notes 15 notes

down

michael at squiloople dot com ¶

10 years ago


current() also works on objects:


<?php


  echo current((object) array('one', 'two')); // Outputs: one


?>

down

strate at yandex dot com ¶

8 years ago


Note, that you can pass array by expression, not only by reference (as described in doc).

<?php
var_dump( current( array(1,2,3) ) ); // (int) 1
?>

down

Vasily Yudin (st-2 at mail dot ru) ¶

7 years ago


If you do current() after using uset() on foreach statement, you can get FALSE in PHP version 5.2.4 and above.
There is example:
<?php
$prices = array(
    0 => '1300990',
    1 => '500',
    2 => '600'
);
foreach($prices as $key => $price){
    if($price < 1000){
        unset($prices[$key]);
    }
}

var_dump(current($prices)); // bool(false)
?>
If you do unset() without foreach? all will be fine.
<?php
$prices = array(
    0 => '1300990',
    1 => '500',
    2 => '600'
);
unset($prices[1]);
unset($prices[2]);

var_dump(current($prices));
?>

down

leozmm at outlook dot com ¶

2 years ago


Array can be passed by both REFERENCE and EXPRESSION on `current`, because current doesn't move array's internal pointer,
this is not true for other functions like: `end`, `next`, `prev` etc.

<?php
    function foo() {return array(1,2,3);}
    echo current(foo());  // this print '1'
    echo end(foo());      // this print error: Only variables should be passed by reference
?>

down

vaclav dot sir at gmail dot com ¶

14 years ago


To that "note": You won't be able to distinguish the end of an array from a boolean FALSE element, BUT you can distinguish the end from a NULL value of the key() function.

Example:
<?php
if (key($array) === null) {
    echo "You are in the end of the array.";
} else {
    echo "Current element: " . current($array);
}
?>

down

mdeng at kabenresearch dot com ¶

18 years ago


For large array(my sample was 80000+ elements), if you want to traverse the array in sequence, using array index $a[$i] could be very inefficient(very slow). I had to switch to use current($a).

down

retestro_REMOVE at SPAM_esperanto dot org dot il ¶

19 years ago


The docs do not specify this, but adding to the array using the brackets syntax:

     <?php $my_array[] = $new_value; ?>

will not advance the internal pointer of the array. therefore, you cannot use current() to get the last value added or key() to get the key of the most recently added element.


You should do an end($my_array) to advance the internal pointer to the end ( as stated in one of the notes on end() ), then


    <?php

     $last_key = key($my_array);  // will return the key

     $last_value = current($my_array);  // will return the value

    ?>



If you have no need in the key, $last_value = end($my_array) will also do the job.


- Sergey.

down

vitalib at 012 dot net dot il ¶

18 years ago


Note that by copying an array its internal pointer is lost:

<?php
$myarray = array(0=>'a', 1=>'b', 2=>'c');
next($myarray);
print_r(current($myarray));
echo '<br>';
$a = $myarray;
print_r(current($a));
?>

Would output 'b' and then 'a' since the internal pointer wasn't copied. You can cope with that problem using references instead, like that:

<?php
$a =& $myarray;
?>

down

sergey dot karavay at gmail dot com ¶

8 months ago


It looks like `current()` is deprectated for calling on objects since PHP 7.4. 

Consider this code

```
$a = new ArrayIterator([1,2,3]);

var_dump(current($a), $a->current());
```

It returns 
```
int(1)
int(1)
```

In PHP 7.3, but in PHP7.4 you get:
```
bool(false)
int(1)
```

And in PHP8:
```
Deprecated: current(): Calling current() on an object is deprecated in /in/fdrNR on line 5
bool(false)
int(1)
```

down

pdarmis at gmail dot com ¶

4 years ago


Based on this example http://php.net/manual/en/function.current.php#116128 i would like to add the following.  As Vasily points out in his example 
<?php
$prices = array(
    0 => '1300990',
    1 => '500',
    2 => '600'
);
foreach($prices as $key => $price){
    if($price < 1000){
        unset($prices[$key]);
    }
}

var_dump(current($prices)); // bool(false)
?>
The above example will not work and return false for version of PHP between 5.2.4 and 5.6.29. The issue is not present on PHP versions >= 7.0.1
A different workaround (at least from Vasily's example) would be to use reset() before using current() in order to reset the array pointer to start.
<?php
$prices = array(
    0 => '1300990',
    1 => '500',
    2 => '600'
);
foreach($prices as $key => $price){
    if($price < 1000){
        unset($prices[$key]);
    }
}
reset($prices);
var_dump(current($prices)); // string(7) "1300990"
?>

down

xedin dot unknown at gmail dot com ¶

3 years ago


Array functions, such as `current()` and `rewind()` will work on `Traversable` as well, PHP 5.0 - 7.3, but not in HHVM:

<?php

$queue = new ArrayIterator(array('adasdasd'));
reset($queue);
$current = current($queue);
var_dump($current);

?>

See https://3v4l.org/VjCHR

down

gregory at gregory dot net ¶

14 years ago


It took me a while to figure this out, but there is a more consistent way to figure out whether you really went past the end of the array, than using each().

You see, each() gets the value BEFORE advancing the pointer, and next() gets the value AFTER advancing the pointer. When you are implementing the Iterator interface, therefore, it's a real pain in the behind to use each().

And thus, I give you the solution:
To see if you've blown past the end of the array, use key($array) and see if it returns NULL. If it does, you're past the end of the array -- keys can't be null in arrays.

Nifty, huh? Here's how I implemented the Iterator interface in one of my classes:

<?php

/**
 * DbRow file
 * @package PalDb
 */

/**
 * This class lets you use Db rows and object-relational mapping functionality.
 */

class DbRow implements Iterator
{
    /**
     * The DbResult object that gave us this row through fetchDbRows
     * @var DbResult
     */
    protected $result;
    
    /**
     * The fields of the row
     * @var $fields
     */
    protected $fields;
        
    /**
     * Constructor
     *
     * @param PDOStatement $stmt
     *  The PDO statement object that this result uses
     * @param DbResult $result
     *  The result that produced this row through fetchDbRows 
     */
    function __construct($result)
    {
        $this->result = $result;
    }
    
    /**
     * Get the DbResult object that gave us this row through fetchDbRows
     * @return DbResult
     *
     * @return unknown
     */
    function getResult()
    {
        return $this->result;
    }
    
    function __set(
        $name, 
        $value)
    {
        $this->fields[$name] = $value;
    }
    
    function __get(
        $name)
    {
        if (isset($this->fields[$name])) 
            return $this->fields[$name];
        else
            return null;
    }
    
    /**
     * Iterator implementation - rewind
     */
    function rewind()
    {
        $this->beyondLastField = false;
        return reset($this->fields);
    }
    
    function valid()
    {
        return !$this->beyondLastField;
    }
    
    function current()
    {
        return current($this->fields);
    }
    
    function key()
    {
        return key($this->fields);
    }
    
    function next()
    {
        $next = next($this->fields);
        $key = key($this->fields);            
        if (isset($key)) {
            return $next[1];
        } else {
            $this->beyondLastField = true;
            return false; // doesn't matter what we return here, see valid()
        }
    }
    
    private $beyondLastField = false;
};

Hope this helps someone.

down

-4

Pratip Ghosh ¶

8 years ago


If we unset any element from an array, and then try the current function, I noted it returned FALSE. To overcome this limitation, you can use array_values function to re-order the tree.

down

-8

aefxx ¶

14 years ago


A simple copy function that not only copies the given array but ensures the copy's pointer is set to the exact same position:


<?php

function array_copy(&array)

{

    $key = key($array);

    $copy = $array;


    while (($copy_key = key($copy)) !== NULL) {

        if ($copy_key == $key) break;

        next($copy);

    }


    return $copy;

}

?>



That's all ... bye.

down

-6

jodevweb at gmail dot com ¶

5 years ago


As Sergey stated a long time ago in this notes, when adding to the array using the brackets syntax, current won't return the last added value. Instead of moving the pointer with end(), you simply can get the last value with <?php $my_array[count($my_array) - 1] ?> (only applies to a non-associative array).

add a note

官方地址：https://www.php.net/manual/en/function.current.php

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PHP官方手册 - 互联网笔记

current

说明

参数

返回值

更新日志

范例

注释

参见

User Contributed Notes 15 notes