current
(PHP 4, PHP 5)
current — Возвратить текущий элемент массива
Описание
У каждого массива имеется внутренний указатель на его "текущий" элемент, который инициализирован первым элементом, добавленным в массив.
Функция current() просто возвращает значение элемента массива, на который указывает его внутренний указатель. Она не перемещает указатель куда бы то ни было. Если внутренний указатель за пределами списка элементов, current() возвращает FALSE.
Если массив содержит пустые элементы (0 или "", пустая строка), эта функция возвратит FALSE для этих элементов. Это делает невозможным установить в действительности ли достигнут конец списка элементов массива при помощи функции current(). Для того, чтобы правильно просматривать массивы, содержащие пустые элементы, используйте функцию each().
Пример #1 Пример использования current() и дружественных функций
<?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';
?>
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Расширения, относящиеся к переменным и типам
- Массивы
- array_change_key_case
- array_chunk
- array_column
- array_combine
- array_count_values
- array_diff_assoc
- array_diff_key
- array_diff_uassoc
- array_diff_ukey
- array_diff
- array_fill_keys
- array_fill
- array_filter
- array_flip
- array_intersect_assoc
- array_intersect_key
- array_intersect_uassoc
- array_intersect_ukey
- array_intersect
- array_key_exists
- array_keys
- array_map
- array_merge_recursive
- array_merge
- array_multisort
- array_pad
- array_pop
- array_product
- array_push
- array_rand
- array_reduce
- array_replace_recursive
- array_replace
- array_reverse
- array_search
- array_shift
- array_slice
- array_splice
- array_sum
- array_udiff_assoc
- array_udiff_uassoc
- array_udiff
- array_uintersect_assoc
- array_uintersect_uassoc
- array_uintersect
- array_unique
- array_unshift
- array_values
- array_walk_recursive
- array_walk
- array
- arsort
- asort
- compact
- count
- current
- each
- end
- extract
- in_array
- key_exists
- key
- krsort
- ksort
- list
- natcasesort
- natsort
- next
- pos
- prev
- range
- reset
- rsort
- shuffle
- sizeof
- sort
- uasort
- uksort
- usort
Коментарии
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.
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;
?>
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($a).To that "note": You won't be able to distinguish the end of an array from a boolean FALSE element, BUT you can distinguish the end from a NULL value of the key() function.
Example:
<?php
if (key($array) === null) {
echo "You are in the end of the array.";
} else {
echo "Current element: " . current($array);
}
?>
current() also works on objects:
<?php
echo current((object) array('one', 'two')); // Outputs: one
?>
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
?>
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));
?>
Based on this example function.current#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"
?>
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
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
?>
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)
```