(PHP 4, PHP 5, PHP 7)
each — Restituisce la corrente coppia chiave/valore di un array e incrementa il puntatore dell'array
Restituisce la corrente coppia chiave/valore corrente di
array e incrementa il puntatore interno dell'array. Questa
coppia è restituita in un array di quattro elementi, con le chiavi
0, 1,
key, and
value. Gli elementi 0 e
key contengono il nome della chiave dell'elemento
dell'array, mentre 1 e
value contengono i dati.
Se il puntatore interno dell'array punta oltre la fine dei
contenuti dell'array, each() restituisce
false.
Example #1 esempi dieach()
<?php
$foo = array("bob", "fred", "jussi", "jouni", "egon", "marliese");
$bar = each($foo);
print_r($bar);
?>$bar ora contiene la seguente coppia chiave/valore:
Array
(
[1] => bob
[value] => bob
[0] => 0
[key] => 0
)
<?php
$foo = array("Robert" => "Bob", "Seppo" => "Sepi");
$bar = each($foo);
print_r($bar);
?>$bar ora contiene la seguente coppia chiave/valore:
Array
(
[1] => Bob
[value] => Bob
[0] => Robert
[key] => Robert
)
each() viene normalmente usata in congiunzione con list() nell'attraversamento di un array; ecco un esempio:
Example #2 Attraversamento di un array con each()
<?php
$frutta = array('a' => 'albicocca', 'b' => 'banana', 'c' => 'ciliegia');
reset($frutta);
while (list($chiave, $valore) = each($frutta)) {
echo "$chiave => $valore\n";
}
?>Outputs:
a => albicocca b => banana c => ciliegia
Dopo l'esecuzione di each(), il puntatore dell'array viene lasciato sull'elemento successivo, o sull'ultimo elemento se si è alla fine dell'array. Si deve utilizzare reset() se si vuole riattraversare l'array usando each().
Poiché assegnare un array ad un'altra variabile reimposta il puntatore, il nostro esempio diventerebbe un loop infinito se assegnassimo $frutta ad un'altra variabile all'interno del ciclo.
Vedere anche key(), list(), current(), reset(), next(), prev() e foreach.
Following the obsolescence of the each() function, here is a way to correct your source codes:
If you use each() in a while loop like this:
while (list($Key,$Value)=@each($Array)){
....
}
you have to replace with
foreach ($Array as $Key => $Value){
....
}
In the same minds.
while (list(,$Value)=@each($Array)){
....
}
will become
foreach ($Array as $Value){
....
}Regarding speed of foreach vs while(list) =each
I wrote a benchmark script and the results are that clearly foreach is faster. MUCH faster. Even with huge arrays (especially with huge arrays). I tested with sizes 100,000. 1,000,000 and 10,000,000. To do the test with 10 million i had to set my memory limit real high, it was close to 1gb by the time it actually worked. Anyways,
<?php
function getDiff($start, $end) {
$s = explode(' ', $start);
$stot = $s[1] + $s[0];
$e = explode(' ', $end);
$etot = $e[1] + $e[0];
return $etot - $stot;
}
$lim=10000000;
$arr = array();
for ($i=0; $i<$lim; $i++) {
$arr[$i] = $i/2;
}
$start = microtime();
foreach ($arr as $key=>$val);
$end = microtime();
echo "time for foreach = " . getDiff($start, $end) . ".\n";
reset($arr);
$start = microtime();
while (list($key, $val) = each($arr));
$end = microtime();
echo "time list each = " . getDiff($start, $end) . ".\n";
?>
here are some of my results: with 1,000,000
time for foreach = 0.0244591236115.
time list each = 0.158002853394.
desktop:/media/sda5/mpwolfe/tests$ php test.php
time for foreach = 0.0245339870453.
time list each = 0.154260158539.
desktop:/media/sda5/mpwolfe/tests$ php test.php
time for foreach = 0.0269000530243.
time list each = 0.157305955887.
then with 10,000,000:
desktop:/media/sda5/mpwolfe/tests$ php test.php
time for foreach = 1.96586894989.
time list each = 14.1371650696.
desktop:/media/sda5/mpwolfe/tests$ php test.php
time for foreach = 2.02504014969.
time list each = 13.7696218491.
desktop:/media/sda5/mpwolfe/tests$ php test.php
time for foreach = 2.0246758461.
time list each = 13.8425710201.
by the way, these results are with php 5.2 i believe, and a linux machine with 3gb of ram and 2.8ghz dual core pentiumeach was deprecated because it exposed too much of the internal implementation details, blocking language development. ("We can't do X because it would break each().")
https://wiki.php.net/rfc/deprecations_php_7_2#each
If you want an array pointer, maintain it yourself. Probably a good idea anyway, because then it's visible in the code.This function is marked as deprecated in PHP 7.2.0 and is removed in PHP 8.0.0, the replacement for legacy code would look like this:
function legacy_each($array){
$key = key($array);
$value = current($array);
$each = is_null($key) ? false : [
1 => $value,
'value' => $value,
0 => $key,
'key' => $key,
];
next($array);
return $each;
}Hello, since each() and list() often "betray" very old applications, I simply recommend not to use them anymore.
If you want to assign variables based on an associative array,
Replace this:
while(list ($key, $value) = each ($my_array)) {
$$key = $value;
}
with this:
foreach ($my_array as $key => $value) {
$$key = $value;
}Use foreach instead of while, list and each. Foreach is:
- easier to read
- faster
- not influenced by the array pointer, so it does not need reset().
It works like this:
<?php
$arr = array('foo', 'bar');
foreach ($arr as $value) {
echo "The value is $value.";
}
$arr = array('key' => 'value', 'foo' => 'bar');
foreach ($arr as $key => $value) {
echo "Key: $key, value: $value";
}
?>Rector has an automated fix ('ListEachRector') to migrate away from `each()`:
https://github.com/rectorphp/rector/blob/master/docs/AllRectorsOverview.md#listeachrector
If you look at the code example you'll see this is even quite simple to do by hand.It's worth noting that references to an array don't have thier own array pointer, and taking a reference to an array doesn't reset it's array pointer, so this works as you would expect it would by eaching the first three items of the array, rather than the first item 3 times.
<?php
$x = array(1,2,3);
print_r(each($x));
echo "\n";
$y =& $x;
print_r(each($y));
echo "\n";
$z =& $y;
print_r(each($z));
echo "\n";
?>If you want to display the hole structure (tree) of your array, then you can use this recursive solution.
<?PHP
$tree= "";
array_tree($your_array);
echo $tree;
// Recursive Function
function array_tree($array, $index=0){
global $tree;
$space="";
for ($i=0;$i<$index;$i++){
$space .= " ";
}
if(gettype($array)=="array"){
$index++;
while (list ($x, $tmp) = each ($array)){
$tree .= $space."$x => $tmp\n";
array_tree($tmp, $index);
}
}
}
?>An odd function to deprecate. If you're keeping track of an array pointer in a collection outside a foreach loop you don't care about performance and the utility of this function is core.
Instead you must call two functions: current() and then next() to replicate its behaviour.If you want to iterate over a two-dimensional, sparse array, and want to first display every first element, then every second and so on, you can use this code:
$fruits = array ( "fruits" => array ( "a" => "orange",
"b" => "banana",
"c" => "apple"
),
"numbers" => array ( 1,
2,
3,
4,
5,
6
),
"holes" => array ( "first",
5 => "second",
"third",
10 => "fourth",
)
);
$done = False;
while ($done == False) {
$done = True;
// Important: &$val has to be a reference (use the &),
// if you don't, the internal counter of $val will be
// re-initialized each time and you loop over the first elements
// for eternity.
foreach($fruits as $key => &$val) {
if (list($inner_key, $inner_val) = each(&$val)) {
$done = False;
echo "$key : : $inner_key => $inner_val <br> \n";
}
}
}
NOTE: this is just a quick hack, if you know a better way, post it!This function will help you dump any variable into XML structure.
//dump var into simple XML structure
function var_dump_xml($tagname,$variable,$level=0)
{
for($i=0;$i<$level;$i++) $marg.=' ';
if (eregi('^[0-9].*$',$tagname)) $tagname='tag_'.$tagname; //XML tag cannot start with [0-9] character
if (is_array($variable))
{
echo $marg."<$tagname>\n";
while (list ($key, $val) = each ($variable)) var_dump_xml($key,$val,$level+1);
echo $marg."</$tagname>\n";
}
elseif (strlen($variable)>0)
{
echo $marg."<$tagname>".htmlspecialchars($variable)."</$tagname>\n";
};
};
/*
example:
$myVar = array("name"=>"Joe", "age"=>"26", "children"=>array("Ann","Michael"));
var_dump_xml("myVarTag",$myVar);
*/To panania at 3ringwebs dot com:
If you know for certain that you are only receiving one row, the while becomes redundant. To shorten your code:
$strSQL = "SELECT * FROM table WHERE id=1";
$RecordsetSelect = $db->runQuery ($strSQL);
list($key, $val) = mysql_fetch_row($RecordsetSelect);
echo "$key => $val\n";
mysql_free_result($RecordsetSelect);
With only one row being returned this is more elegant a solution, but just being nit-picky in essence. It also shows another quick way of using list.If you forget to reset the array before each(), the same code may give different results with different php versions.
<?php
$a = array(1,2,3);
foreach ($a AS $k => $v) $a[$k] = 2*$v;
while(list($k2, $v2) = each($a)) { echo($v2."\n"); }
?>
In PHP 5.2.0:
2
4
6
In PHP 5.2.6:
4
6I usually work a lot with 2D arrays. Since I've had some trouble traversing them correctly maybe someone out there also experienced those problems and can use this one.
It's based on a 2D-array called $array[$x][$y]. At some (but not necessarily all) (x,y) there is a value I want to reach. Note that I do not know beforehand the ranges of $x or $y (that is their highest and lowest values).
while (list ($x, $tmp) = each ($array)) {
while (list ($y, $val) = each ($tmp)) {
echo "$x, $y, $val";
}
}
The answer for each (x,y) pair can thus be (providng, of course those values where in your array beforehand):
1, 1, 2
2, 2, 0
3, 1, 1
5, 2, 2
5, 1, 2
Note that only the (x,y) pairs with a corresponding value is shown.
Hang in there
Jon Egil Strand
NTNUI've found a compact way to cycle through an associative array using for statement (not while, as it has been done in the most of examples below):
<?php
for (reset($array); list($key) = each($array);) {
echo $key;
echo $array[$key];
}
?>
or
<?php
for (reset($array); list($key, $value) = each($array);) {
echo $key;
echo $value;
echo $array[$key];
}
?>
You hardly forget to add reset($array) code line using such construction.Be sure to use the integrated functions "unset();" or "reset();" - many people forget this and wonder about the created output!In PHP 7.2 we can use foreach() to replace each(), such as:
foreach($array as $key => $value) {
//do something
}I wrote a short and pretty simple script to search through associative arrays for some value in the values, heres a simplifyed example of it:
<?php
$foo['bob'] = "bob is ugly";
$foo['bill'] = "bill is rich";
$foo['barbie'] = "barbie is cute";
$search = "rich";
echo "searching the array foo for $search:<br>";
reset ($foo);
while (list ($key, $val) = each ($foo)) {
if (preg_match ("/$search/i", $val)) {
print "A match was found in $key.<br />";
} else {
print "A match was not found in $key.<br />";
}
}
?>
will output:
Searching the array foo for rich:
A match was not found in bob
A match was found in bill
A match was not found in barbieI wanted to be able to add to an array while looping through it. foreach does not allow this because it is using a secret copy of the array. each makes this possible (tested on PHP 4).
<?php
$shopping_list = array('oysters', 'caviare');
reset ($shopping_list);
while (list($key, $value) = each ($shopping_list)) {
if ($value == 'oysters') $shopping_list[] = 'champagne';
elseif ($value == 'champagne') $shopping_list[] = 'ice';
}
print_r($shopping_list);
// Array ( [0] => oysters [1] => caviare [2] => champagne [3] => ice )
?>Ok Here's one for iterating multidimensional array .. using foreach
<?php
$members = array(
"member1" => array (
"First Name" => "Robert",
"Last Name" => "Burton",
"Age" => "20"
),
"member2" => array (
"First Name" => "Cheska",
"Last Name" => "Vladesk",
"Age" => "21"
),
"member3" => array (
"First Name" => "Gino",
"Last Name" => "Marley",
"Age" => "19"
),
"member4" => array (
"First Name" => "Jake",
"Last Name" => "White",
"Age" => "16"
),
);
$dataSetCount = count($members);
echo "<h1>There are $dataSetCount members</h1>";
$i = 0;
foreach ($members as $each_members) {
$i++;
echo "<h2>Member $i</h2>";
foreach ($each_members as $position => $details) {
echo "<b>$position</b>" . ": " . $details . "<br />";
}
}
?>Remember to use "reset()" if you iterate over an array with "each()" more than once! Example:
while(list($key,$value) = each($array)){
// code here
}
NOW the internal pointer on $array is at the end of the array, and another attempt at an iteration like the one above will result in zero executions of the code within the "while" block. You MUST call "reset($array)" to reset the internal array pointer before iterating over the array again from the first element.<?php
function each_v2($arr) {
// same as each() but when it hits end of array, it resets it
static $i = 0;
if (isset($arr[$i])) {
// exists¸
return $arr[$i++];
} else {
// reset $i to 0 and repeat
$i = 0;
return each_v2($arr);
}
}
?>/* Iterating using objects via each */
class SAI
{
public function __toString()
{
return __CLASS__;
}
}
$a = new SAI();
$b = new SAI();
$c = new SAI();
$d = new SAI();
$e = new SAI();
$objarray = array($a,$b,$c,$d,$e);
reset($objarray);
while (list($key, $val) = each($objarray))
{
echo "$key => $val\n";
}
//Results
0 => SAI
1 => SAI
2 => SAI
3 => SAI
4 => SAI
Warning:
each() will also accept objects, but may return unexpected results. It's therefore not recommended to iterate though object properties with each().