each

gaviel (2011-03-18 03:53:03)

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 />";
                }
            }
    ?>

massimo dot modica at tin dot it (2010-02-03 02:36:32)

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

php at omit dot ianco dot co dot uk (2008-04-13 06:10:55)

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 ) 
?>

wolfeym38 at yahoo dot com (2007-06-11 23:28:21)

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

michael k (name der redaktion bekannt.) (2007-05-10 12:36:44)

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!

sjoerd-php at linuxonly dot nl (2006-03-31 06:04:25)

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 (2005-12-04 15:58:57)

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 (2005-11-24 09:55:14)

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 (2005-07-23 05:17:20)

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 (2004-11-02 07:29:55)

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 (2003-12-31 17:51:50)

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 (2002-08-04 12:41:41)

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 (2002-05-26 10:13:19)

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 (2002-05-08 09:40:18)

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;
};
};
};

(2002-02-13 04:10:35)

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 (2001-01-29 11:33:45)

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 (2000-10-25 13:03:27)

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.

phpmanual at devin dot com (2000-07-14 17:26:33)

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:

<?php

reset($A); while (list($k,) = each($A)) {
    $elem = &$A[$k];
    /* ... */
}

?>

Is needed.  Copy construction would be handy to have here.

ellenzhg at hotmail dot com (2000-03-30 00:06:53)

<?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.

pyxl at dont_spam_on_me dot jerrell dot com (2000-02-16 03:41:11)

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.
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!
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.
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.