(PHP 4, PHP 5, PHP 7, PHP 8)
current — Restituisce l'elemento corrente di un array
Ogni array ha un puntatore interno all'elemento "corrente", che è inizializzato al primo elemento inserito nell'array.
La funzione current() restituisce il
valore dell'elemento che è attualmente puntato dal puntatore
interno. In ogni caso non muove il puntatore. Se il
puntatore interno punta oltre la fine della lista di elementi,
current() restituisce false.
Se l'array contiene elementi vuoti (0 o "", la stringa
vuota) la funzione restituirà false
pure per questi elementi. Questo rende impossibile
stabilire se si è veramente alla fine della lista in un
array di questo tipo usando current(). Per attraversare
in modo corretto un array che può contenere elementi vuoti, usare la
funzione each().
Example #1 Esempio di current() e funzioni relative
<?php
$trasporti = array('piedi', 'bicicletta', 'automobile', 'aereo');
$mode = current($trasporti); // $mode = 'piedi';
$mode = next($trasporti); // $mode = 'bicicletta';
$mode = current($trasporti); // $mode = 'bicicletta';
$mode = prev($trasporti); // $mode = 'piedi';
$mode = end($trasporti); // $mode = 'aereo';
$mode = current($trasporti); // $mode = 'aereo';
?>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), $a->current());
```
It returns
```
int(1)
int(1)
```
In PHP 7.3, but in PHP7.4 you get:
```
bool(false)
int(1)
```
And in PHP8:
```
Deprecated: current(): Calling current() on an object is deprecated in /in/fdrNR on line 5
bool(false)
int(1)
```current() also works on objects:
<?php
echo current((object) array('one', 'two')); // Outputs: one
?>Note, that you can pass array by expression, not only by reference (as described in doc).
<?php
var_dump( current( array(1,2,3) ) ); // (int) 1
?>To that "note": You won't be able to distinguish the end of an array from a boolean FALSE element, BUT you can distinguish the end from a NULL value of the key() function.
Example:
<?php
if (key($array) === null) {
echo "You are in the end of the array.";
} else {
echo "Current element: " . current($array);
}
?>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.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).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));
?>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
?>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/VjCHRNote 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;
?>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"
?>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.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.