In response to "Andrzej Martynowicz at gmail dot com", regarding the use of array_walk with the optional 3rd parameter being modified by reference:
while your solution works, yet another option is to call array_walk like so:
<?php
array_walk($array1, 'userfunction', &$array2byreference);
function userfunction(&$array1value, $key, $array2){
// process $array1value and $array2, $array2 will retain the values
}
?>
array_walk
(PHP 4, PHP 5)
array_walk — 配列の全ての要素にユーザ関数を適用する
説明
bool array_walk ( array &$array, callback $funcname [, mixed $userdata] )成功した場合に TRUE を、失敗した場合に FALSE を返します。
array 配列の各要素にユーザ定義関数 funcname を適用します。通常、 funcname は引数を二つとります。 array パラメータの値が最初の引数、 キー/添字は二番目の引数となります。 オプションの userdata パラメータが指定された場合、 コールバック関数 funcname への三番目の引数として渡されます。
funcname 関数が、指定された引数より多いパラメータを必要とする 場合、array_walk()がfuncname をコールする度にエラーレベル E_WARNING が 発生します。これらの警告は、array_walk() コールの前に PHP エラー演算子 @ を付けるか、error_reporting() により抑制することができます。
注意: funcname により配列の値そのものを変更する必要がある場合、 funcname の最初の引数は 参照 として渡す必要があります。この場合、配列の要素に加えた変更は、 配列自体に対して行われます。
注意: キー及び userdata を funcname に渡す処理は、 バージョン 4.0.0 で追加されました。
array_walk() は array の内部配列ポインタに影響されません。array_walk() はポインタの位置に関わらず配列の全てに渡って適用されます。
コールバック関数により配列自身を変更することはできません。 例えば、要素の追加、削除、要素の unset 等はできません。 array_walk() が適用される配列を 変更しようとすると、関数の動作を定義できず、 予期しない結果を得ることになります。
例 287. array_walk() の例
<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
function test_alter(&$item1, $key, $prefix)
{
$item1 = "$prefix: $item1";
}
function test_print($item2, $key)
{
echo "$key. $item2<br />\n";
}
echo "Before ...:\n";
array_walk($fruits, 'test_print');
array_walk($fruits, 'test_alter', 'fruit');
echo "... and after:\n";
array_walk($fruits, 'test_print');
?>
上の例の出力は以下となります。
Before ...:
d. lemon
a. orange
b. banana
c. apple
... and after:
d. fruit: lemon
a. fruit: orange
b. fruit: banana
c. fruit: apple
array_walk_recursive()、 create_function()、 list()、 foreach、 each()、 call_user_func_array() および array_map() callback 型に関する情報 も参照ください。
array_walk
Jon Langevin >>intel352 : AT : gmail.com
20-Jan-2007 05:15
20-Jan-2007 05:15
hioctiane at hioctiane dot de
22-Dec-2006 07:00
22-Dec-2006 07:00
<?php
/*Thanks to Jerk, thats what I need all the time.
I have a little Upgrade to your code.
Now the values of your $array will be handled by a consign method from a consign object(optional, otherwise taking this operator).*/
class user_function {
function user_function() {
}
/**
*
* handle all values from multidimensional array by $function from $object
*
*/
function walk_multi_array(&$array, $method, $object=NULL) {
//when argument object is given
if (is_object($object)) {
//check if it is object
if (!is_object($object))
return false;
//check if object has method
if (!array_search(strtolower($method), get_class_methods(get_class($object))))
return false;
}
//no argument object is given
else {
//check if this class has method
if (!array_search(strtolower($method), get_class_methods(get_class($this))))
return false;
}
foreach ($array as $key => $value) {
//$value is array
if(is_array($value))
//recursiv call of walk_multi_array
$result[$key] = $this->walk_multi_array(&$value, $method, $object);
//$value is value
else {
if (is_object($object))
$result[$key] = $object->$method($value);
else
$result[$key] = $this->$method($value);
}
}
return $result;
}
}
class test_class {
function test_class() {
}
function strtoup($value) {
return strtoupper($value);
}
}
$test_class = new test_class;
$user_function = new user_function;
$array = array (
1 => "testFall1",
2 => array (
21 => "tesTfaLL21",
22 => array (
221 => "TESTFALL221",
222 => "testfall222"
)
),
3 => "testfall3"
);
echo "<pre>";
print_r($user_function->walk_multi_array($array, 'strtoup', $test_class));
echo "</pre>";
?>
Output:
Array
(
[1] => TESTFALL1
[2] => Array
(
[21] => TESTFALL21
[22] => Array
(
[221] => TESTFALL221
[222] => TESTFALL222
)
)
[3] => TESTFALL3
)
jerk at yoosic dot de
22-Dec-2006 01:05
22-Dec-2006 01:05
if you want to modify every value of an multidimensional array use this function used here:
<?php
$array = array (1=>1, 2=> 2, 3 => array(1=>11, 2=>12, 3=>13));
$text = "test";
function modarr(&$array, $text) {
foreach ($array as $key => $arr) {
if(is_array($arr)) $res[$key] = modarr(&$arr,$text);
// modification function here
else $res[$key] = $arr.$text;
}
return $res;
}
$erg = modarr($array, $text);
print_r($erg);
?>
result will be_
<?php
Array ( [1] => 1test [2] => 2test [3] => Array ( [1] => 11test [2] => 12test [3] => 13test ) )
?>
nihaopaul at nihaopaul dot com
06-May-2006 07:59
06-May-2006 07:59
no sure if this should go under array-walk but it does what i need, it searches a multidimensionial array by using an array to walk it, it either returns a value or an array.
function walker($walk, $array) {
if (count($walk) >0) {
foreach($array as $key => $value) {
if ($key == $walk[0]) {
if (is_array($value)) {
unset($walk[0]);
return walker(array_values($walk), $value);
} else {
if (isset($value)) {
if (count($walk) == 1) {
return $value;
} else {
return 0;
}
} else {
return 0;
}
}
}
}
return 0;
} else {
return $array;
}
}
ludvig dot ericson at gmail dot com
21-Nov-2005 11:09
21-Nov-2005 11:09
In response to 'ibolmo', this is an extended version of string_walk, allowing to pass userdata (like array_walk) and to have the function edit the string in the same manner as array_walk allows, note now though that you have to pass a variable, since PHP cannot pass string literals by reference (logically).
<?php
function string_walk(&$string, $funcname, $userdata = null) {
for($i = 0; $i < strlen($string); $i++) {
# NOTE: PHP's dereference sucks, we have to do this.
$hack = $string{$i};
call_user_func($funcname, &$hack, $i, $userdata);
$string{$i} = $hack;
}
}
function yourFunc($value, $position) {
echo $value . ' ';
}
function yourOtherFunc(&$value, $position) {
$value = str_rot13($value);
}
# NOTE: We now need this ugly $x = hack.
string_walk($x = 'interesting', 'yourFunc');
// Ouput: i n t e r e s t i n g
string_walk($x = 'interesting', 'yourOtherFunc');
echo $x;
// Output: vagrerfgvat
?>
Also note that calling str_rot13() directly on $x would be much faster ;-) just a sample.
ibolmo
18-Nov-2005 12:53
18-Nov-2005 12:53
If anyone is interested to implement the array_walk functionality to a string. I've made this handy function. Note that this can be easily extended for any type of purpose. I've used this to convert from a string of bytes to a hex string then back from hex to a byte string.
<?php
function string_walk($string,$funcname)
{
for($i=0;$i<strlen($string);$i++) {
call_user_func($funcname,$string{$i});
}
}
function yourFunc($val)
{
echo $val.' ';
}
string_walk('interesting','yourFunc');
//ouput: i n t e r e s t i n g
?>
thomas dot hebinck at digionline dot de
31-Oct-2005 11:07
31-Oct-2005 11:07
This is a short way to concatenate a string to each element of an array:
$arr=array(1,2,3,4,5,6,7,8,9,0);
$str=' test'; // must not include ' or " ...
array_walk($arr,create_function('&$elem','$elem .= "' . $str . '";'));
var_export($arr);
The output is:
array ( 0 => '1 test', 1 => '2 test', 2 => '3 test', 3 => '4 test', 4 => '5 test', 5 => '6 test', 6 => '7 test', 7 => '8 test', 8 => '9 test', 9 => '0 test', )
Andrzej Martynowicz at gmail dot com
19-Sep-2005 10:03
19-Sep-2005 10:03
It can be very useful to pass the third (optional) parameter by reference while modifying it permanently in callback function. This will cause passing modified parameter to next iteration of array_walk(). The exaple below enumerates items in the array:
<?
function enumerate( &$item1, $key, &$startNum ) {
$item1 = $startNum++ ." $item1";
}
$num = 1;
$fruits = array( "lemon", "orange", "banana", "apple");
array_walk($fruits, 'enumerate', $num );
print_r( $fruits );
echo '$num is: '. $num ."\n";
?>
This outputs:
Array
(
[0] => 1 lemon
[1] => 2 orange
[2] => 3 banana
[3] => 4 apple
)
$num is: 1
Notice at the last line of output that outside of array_walk() the $num parameter has initial value of 1. This is because array_walk() does not take the third parameter by reference.. so what if we pass the reference as the optional parameter..
<?
$num = 1;
$fruits = array( "lemon", "orange", "banana", "apple");
array_walk($fruits, 'enumerate', &$num ); // reference here
print_r( $fruits );
echo '$num is: '. $num ."\n";
echo "we've got ". ($num - 1) ." fruits in the basket!";
?>
This outputs:
Array
(
[0] => 1 lemon
[1] => 2 orange
[2] => 3 banana
[3] => 4 apple
)
$num is: 5
we've got 4 fruits in the basket!
Now $num has changed so we are able to count the items (without calling count() unnecessarily).
As a conclusion, using references with array_walk() can be powerful toy but this should be done carefully since modifying third parameter outside the array_walk() is not always what we want.
webmaster at tmproductionz dot com
19-Jul-2005 04:54
19-Jul-2005 04:54
to the note right before this one. that will only trim leading and trailing white space. if you want to trim white space inside the string (ie 'hello world' to 'hello world') you should use this:
$val = preg_replace ( "/\s\s+/" , " " , $val ) ;
this will also trim leading and trailing white space.
el_porno at web dot de
27-May-2005 07:03
27-May-2005 07:03
You want to get rid of the whitespaces users add in your form fields...?
Simply use...:
class SomeVeryImportantClass
{
...
public function mungeFormData(&$data)
{
array_walk($data, array($this, 'munge'));
}
private function munge(&$value, &$key)
{
if(is_array($value))
{
$this->mungeFormData($value);
}
else
{
$value = trim($value);
}
}
...
}
so...
$obj = new SomeVeryImportantClass;
$obj->mungeFormData($_POST);
___
eNc
caliban at darklock dot com
24-May-2005 02:33
24-May-2005 02:33
> I believe this relies on the deprecated runtime
> pass-by-reference mechanism
The array() keyword is a language construct, not a function, so I don't think this is applicable.
Enlightened One
08-Apr-2005 03:17
08-Apr-2005 03:17
Beware that "array ($this, method)" construct. If you're wanting to alter members of the "$this" object inside "method" you should construct the callback like this:
$callback[] = &$this;
$callback[] = method;
array_walk ($input, $callback);
Creating your callback using the array() method as suggested by "appletalk" results in a copy of $this being passed to method, not the original object, therefor any changes made to the object by method will be lost when array_walk() returns. While you could construct the callback with "array(&$this, method)", I believe this relies on the deprecated runtime pass-by-reference mechanism which may be removed in future releases of PHP. Better to not create a dependence on that feature now than having to track it down and fix it in the future.
Hayley Watson
17-Jan-2005 11:27
17-Jan-2005 11:27
As well as being able to pass the array the callback will be working on by reference, one can pass the optional userdata parameters by reference also:
<?php
function surprise($x,$key,$xs)
{
//$key is unused here.
$x.='!';
array_push($xs,$x);
}
$array1 = array('this','that','the other');
$array2 = array();
array_walk($array1,'surprise',&$array2);
print_r($array1);
print_r($array2);
?>
Of course, that precise example would be better handled by array_map, but the principle is there.
appletalk at gmail dot com
23-Dec-2004 11:26
23-Dec-2004 11:26
To use array_walk with a class simply do:
array_walk($input, array($this, method) );
memandeemail at gmail dot com
11-Nov-2004 10:24
11-Nov-2004 10:24
If you are using array_walk on a class, dont will work
so ... try this on your own class:
class your_own_class {
/**
* @return void
* @param array $input
* @param string $funcname
* @desc A little workaround, do the same thing.
*/
function array_walk($input, $funcname) {
foreach ($input as $key => $value) $this->$funcname($value, $key);
}
}
05-Nov-2004 04:22
If array_walk_recursive() is not present and you want to apply htmlentities() on each array element you can use this:
function array_htmlentities(&$elem)
{
if (!is_array($elem))
{
$elem=htmlentities($elem);
}
else
{
foreach ($elem as $key=>$value)
$elem[$key]=array_htmlentities($value);
}
return $elem;
} // array_htmlentities()
If you want to output an array with print_r() and you have html in it this function is very helpful.
lgaga dot dont dot spam at muszaki dot info
16-Oct-2004 11:31
16-Oct-2004 11:31
Behaviour like array_walk_recursive() can be achieved in php <=5 by a callback function to array_walk() similar to this:
function walkcallback(&$val,$key) {
if (is_array($val)) array_walk($val,'walkcallback',$new);
else {
// do what you want with $val and $key recursively
}
}
bisqwit at iki dot fi
04-Sep-2004 08:54
04-Sep-2004 08:54
It's worth nothing that array_walk can not be used to change keys in the array.
The function may be defined as (&$value, $key) but not (&$value, &$key).
Even though PHP does not complain/warn, it does not modify the key.
paul at heliosville dot com
04-Sep-2004 04:13
04-Sep-2004 04:13
one rather important note that was lost in the Great PHP Doc Note Purge of '04 is that you can call methods using array_walk(). Let's assume that we have a class named 'Search', in which there is a method called 'convertKeywords'. Here's how you would call that convertKeywords method from inside the class:
array_walk($keywords, array($this, 'convertKeywords'));
Notice that, instead of giving a string as the second argument, you give an array with two items: the variable that holds the class (in this case, $this), and the method to call. Here's what it would look like if you were to call convertKeywords from an already-instantiated class:
$search = new Search;
array_walk($keywords, array($search, 'convertKeywords'));
Eierkoek
03-Sep-2004 10:46
03-Sep-2004 10:46
normaly the $_GET array will add slashes to the array values. To remove all slashes in this array, i created the folowing code
set_magic_quotes_runtime (0);
function StripAllSlashes (&$ArrayGET, $Value)
{
if (is_array ($ArrayGET)) array_walk ($ArrayGET, "StripAllSlashes");
else $ArrayGET = stripslashes ($ArrayGET);
}
if (isset ($_GET) && get_magic_quotes_gpc ()) array_walk ($_GET, "StripAllSlashes");
I hope this code was usefull,
Eierkoek