each

(PHP 4, PHP 5)

eachDevolver el par clave/valor actual de un array y avanzar el cursor del array

Descripción

array each ( array &$array )

Devuelve el par clave/valor actual de un array y avanza el cursor del array.

Después de que each() haya sido ejecutado, el cursor del array será puesto en el siguiente elemento del array, o pasado el último elemento si alcanza el final del array. Se tiene que usar reset() si se quiere atravesar de nuevo el array usando each.

Parámetros

array

El array de entrada.

Valores devueltos

Devuelve el par clave/valor actual del array dado por array. Este par es devuelto en un array de cuatro elementos, con las claves 0, 1, key, y value. Los elementos 0 y key contienen el nombre de la clave del elemento del array, y 1 y value contienen la información.

Si el puntero interno del array apunta al final del contenido de array, each() devuelve FALSE.

Ejemplos

Ejemplo #1 Ejemplo de each()

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

$bar ahora contienelos siguientes pares clave/valor:

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

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

$bar ahora contienelos siguientes pares clave/valor:

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

each() se usa normalmente junto con list() para atravesar un array. Aquí hay un ejemplo:

Ejemplo #2 Atravesar un array con each()

<?php
$fruta 
= array('a' => 'manzana''b' => 'banana''c' => 'arándano');

reset($fruta);
while (list(
$clave$valor) = each($fruta)) {
    echo 
"$clave => $valor\n";
}
?>

El resultado del ejemplo sería:

a => manzana
b => banana
c => arándano

Precaución

Ya que asignar un array a otra variable reinicia el puntero del array original (nuestro ejemplo de arriba causaría un bucle sin fin), hemos asignado $fruta a otra variable dentro del bucle.

Advertencia

each() también aceptará objetos, pero puede devolver resultados inesperados. Por lo tanto, no se recomienda iterar propiedades de objetos con each().

Ver también

  • key() - Obtiene una clave de un array
  • list() - Asigna variables como si fuera un array
  • current() - Devuelve el elemento actual en un array
  • reset() - Establece el puntero interno de un array a su primer elemento
  • next() - Avanza el puntero interno de un array
  • prev() - Rebobina el puntero interno del array
  • foreach
  • Iteración de Objetos

add a note add a note

User Contributed Notes 15 notes

up
18
wolfeym38 at yahoo dot com
7 years ago
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 pentium
up
3
james at gogo dot co dot nz
10 years ago
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";
?>
up
8
sjoerd-php at linuxonly dot nl
8 years ago
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";
}
?>
up
2
matthew at mhalls dot net
8 years ago
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.
up
3
michael k (name der redaktion bekannt.)
7 years ago
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!
up
2
Sopinon
9 years ago
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);
        }
    }
}
?>
up
1
amby2 at izh dot com
8 years ago
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.
up
1
php at omit dot ianco dot co dot uk
6 years ago
I 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 )
?>
up
1
wodzuY2k at anronet dot pl
12 years ago
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);
        */
up
2
Gillis at dancrea dot com
12 years ago
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
up
2
Anonymous
12 years ago
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
up
0
gaviel
3 years ago
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 />";
                }
            }
   
?>
up
0
massimo dot modica at tin dot it
4 years ago
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
6
up
0
tk at turtle-entertainment dot de
13 years ago
Be sure to use the integrated functions "unset();" or "reset();" - many people forget this and wonder about the created output!
up
0
kris at angelanthony dot com
14 years ago
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.
To Top