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Last updated: Sat, 27 Jan 2007

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# each

(PHP 3, PHP 4, PHP 5)

each -- Возвратить текущую пару ключ/значение из массива и сместить его указатель

## Описание

array each ( array &array )

Возвращает текущую пару ключ/значение из массива `array` и смещает его указатель. Эта пара возвращается в виде массива из четырёх элементов, со следующими ключами: `0`, `1`, `key` и `value`. Элементы `0` и `key` содержат ключ элемента массива, а элементы `1` и `value` содержат его значение.

Если внутренний указатель массива указывает на его конец, each() возвратит `FALSE`.

Пример 1. Примеры использования each()

`<?php $foo = array("bob", "fred", "jussi", "jouni", "egon", "marliese"); $bar = each($foo); print_r($bar); ?>`

`$bar` теперь содержит следующие пары ключ/значение:

    Array
    (
        [1] => bob
        [value] => bob
        [0] => 0
        [key] => 0
    )

`<?php $foo = array("Robert" => "Bob", "Seppo" => "Sepi"); $bar = each($foo); print_r($bar); ?>`

`$bar` теперь содержит следующие пары ключ/значение:

    Array
    (
        [1] => Bob
        [value] => Bob
        [0] => Robert
        [key] => Robert
    )

each() обычно используется совместно с list() для обхода массива, как в этом примере:

Пример 2. Обход массива функцией each()

`<?php
$fruit = array('a' => 'apple', 'b' => 'banana', 'c' => 'cranberry');
reset($fruit);
while (list($key, $val) = each($fruit)) {
echo "$key => $val
";
}
?>`

Результат выполнения данного примера:

    a => apple
    b => banana
    c => cranberry

После выполнения each(), указатель массива перемещается к следующему его элементу, пока не будет достигнут конец массива. Вы можете использовать функцию reset() для повторного обхода массива при помощи each.

Предостережение
Посколько добавление элемента в массив сбрасывает указатель, вышеприведённый пример может привести бесконечному циклу, если мы будем присваивать `$fruit` другие значения внутри цикла.

См. также key(), list(), current(), reset(), next(), prev() и foreach.

add a note User Contributed Notes
each
mindilator at yahoo dot com
15-Nov-2006 08:58
`You can nest foreach loops too, though.`
Bleach984
09-Nov-2006 05:43
`have found something interesting.
when I use a FOREACH with the WHILE statement inside it as talk has been going on,
it will give you all of the values of a multi-dimensional array.
like this
<?php
$categories = return_cats();
foreach ( $categories as $category ) {
while(list($k, $v) = each ($category)) {
echo "$k ... $v <br />";
}
}
?>
will output something like this
Truecat_name ... Awesome
category_nicename ... awesome
cat_count ... 3
lastday ... 28
lastmonth ... 10
cat_name ... Uncategorized
category_nicename ... uncategorized
cat_count ... 1
lastday ... 28
lastmonth ... 10
cat_name ... Welcome Messages
category_nicename ... welcome-messages
cat_count ... 3
lastday ... 28
lastmonth ... 10`
Michael
29-Jul-2006 01:02
`Something that I found useful to note is that each() does NOT return a reference to the array contets, but a copy of the item.
So, say you have:
$boxes = Array();
$boxes["Large"] = Array();
$boxes["Medium"] = Array();
$boxes["Small"] = Array();
and want to put the small box inside the medium box inside the large box, doing:
$lastBox = NULL;
while (list($key, $box) = each($boxes)) {
if (isset($lastBox))
$lastBox[0] =& $box;
$lastBox =& $box;
}
will not work. Instead, you have to use the key like:
$lastBox = NULL;
while (list($key) = each($boxes)) {
$box =& $boxes[$key];
if (isset($lastBox))
$lastBox[0] =& $box;
$lastBox =& $box;
}
which will work.`
scin
03-May-2006 08:29
`Regarding the user who states that foreach is faster, this depends on the size of the array you are dealing with.
On large arrays while(list($key, $val) = each($array) is considerably faster, as in 10x faster with arrays that number in the millions of elements.`
sjoerd-php at linuxonly dot nl
31-Mar-2006 06:04
`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";
}
?>`
matthew at mhalls dot net
04-Dec-2005 03:58
`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.`
amby2 at izh dot com
24-Nov-2005 09:55
`I'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.`
Sopinon
23-Jul-2005 05:17
`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);
}
}
}
?>`
james at gogo dot co dot nz
02-Nov-2004 07:29
`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";
?>`
panania at 3ringwebs dot com
31-Dec-2003 05:51
`The last method for record sets is great if you don't know the number of rows returned from a query, but if you do there's an easier way...
$strSQL = "SELECT * FROM table WHERE id=1";
$RecordsetSelect = $db->runQuery ($strSQL);
$row_Recordset1 = mysql_fetch_assoc($RecordsetSelect);
while (list($key, $val) = each($row_Recordset1)) {
echo "$key => $val\n";
}
mysql_free_result($RecordsetSelect);
Here we know that only 1 record will be returned because of the WHERE criteria. (Of course this is dependent on you own DB schema.)`
wodzuY2k at anronet dot pl
04-Aug-2002 12:41
`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);
*/`
Gillis at dancrea dot com
26-May-2002 10:13
`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 barbie`
wodzuY2k at anronet dot pl
08-May-2002 09:40
`Yet another useful example of how to make globals out of the config file.
config file:
[section1]
value=foo
PHP result :
variable: $section1_value=foo;
function servicesConfig_makeGlobals()
{
global $servicesConfig;
$servicesConfig = parse_ini_file("servicesConfig.conf", TRUE);
reset($servicesConfig);
while (list ($section, $section_val) = each ($servicesConfig))
{
reset($servicesConfig[$section]);
while (list ($key, $val) = each ($servicesConfig[$section]))
{
$GLOBALS[$section.'_'.$key]=$val;
};
};
};`
13-Feb-2002 04:10
`I 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, $val";
}
}
The answer for each (x,y) pair can thus be (providng, of course those values where in your array beforehand):
1, 1, 2
2, 2, 0
3, 1, 1
5, 2, 2
5, 1, 2
Note that only the (x,y) pairs with a corresponding value is shown.
Hang in there
Jon Egil Strand
NTNU`
tk at turtle-entertainment dot de
29-Jan-2001 11:33
`Be sure to use the integrated functions "unset();" or "reset();" - many people forget this and wonder about the created output!`
kris at angelanthony dot com
25-Oct-2000 01:03
`Remember to use "reset()" if you iterate over an array with "each()" more than once! Example:
while(list($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.`
aryn at aryn dot nu
28-Jul-2000 08:34
`one way to get variables out of an array dynamically, while skipping the keys is this:
while( list($key,$value)=each($foo)) {
if (!is_int($key)) {
echo "$"."$key: $value\n";
$$key = $value;
}
}
(the echo line is just for displaying what is variables are getting set; ie: not needed.)`
phpmanual at devin dot com
14-Jul-2000 05:26
`Note further that each() performs a shallow copy
of the value side of an (assoc) array; if you need to iterate on deep structures, something like:<br>
reset($A); while (list($k,) = each($A)) {<br>
$elem = &$A[$k];<br>
/* ... */<br>
}<br>
Is needed. Copy construction would be handy to have here.`
ellenzhg at hotmail dot com
30-Mar-2000 12:06
`<?php
//each.php
$foo = array( "Robert" => "Bob", "Seppo" => "Sepi" );
$bar = each( $foo );
$k = implode(array_keys($bar),",");
$v = implode(array_values($bar),",");
echo $k ."<br>";
echo $v;
?>
output:
1,value,0,key
Bob,Bob,Robert,Robert
Above example only be interpretered by PHP4.`
ridcully at magnet dot at
22-Mar-2000 06:03
`To output all entries of an array $a, do this
reset ($a);
while( $res=each($a) )
{
echo "$res[1]<br>";
};
If you need the keys too, it's in $res[0].`
pyxl at dont_spam_on_me dot jerrell dot com
16-Feb-2000 03:41
`Ok, for you folks who are learning this, here's something that should help your comprehension of each(), because I bashed my brains for a while on this one.<br><br>
The first example indicates that each() spits out a 4-cell 1 dimensional array. This is all fine and dandy until you get to the second example, where that seems to be thrown out the window, because though each() is still spitting out 4 array elements, the list() being used is set up to only accept 2 values, as it's being executed with only wo variables in it!<br><br>
For some folks, this might not be a problem, but I couldn't understand the mismatch - why was it done, and where did the array go that each() generated?? Well, upon executing that code, it turns out that the first two array elements of the 4 element array that each() creates are assigned to those two variables, and the last two array element values are just thrown away - they're totally ignored. It's how PHP is written.<br><br>
Now, why do that? Well, the example was definitely written more to show folks how to use each() to make life much easier when dealing with a particular operations array in PHP that a lot of people work with, but it also has the side effect (which hopefully my little explaination has made more palatable) of demonstrating how each() can act when being used with other functions that don't necessarily want all of each()'s input.`
steve at juggler dot net
07-Feb-2000 01:02
`As of PHP 4.0b3, the interpreter's not quite smart enough to manage the following:
while(list($k,$v)=each(array("first","second","third")) {
Instead, use:
$ary=array("first","second","third");
while (list($k,$v)=each($ary)) {`
php-traversing-matrices at mark dot datasys dot net
28-Nov-1999 08:47
`Traversing multidimensional arrays is
easy, especially if you know how many dimensions are involved. Suppose you have a structure returned from a database query, such as
$returned_rows[$row_number][$field_name]
To walk through each field, you
might try this:
while (
list($row_number, $row_array)
= each($query_result_array)
) {
while (
list($field_name, $field_value)
= each($row_array)
) {
##
## $row_number has the
## current row number,
## $field_name hsa the current
## field' name,
## $field_value has the current ## field's value
}
}
}`
add a note
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Last updated: Sat, 27 Jan 2007
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