If the class is static:

Otherwise:

PHP ignored arguments type when using array_walk() even if there was

declare(strict_types=1) .

See this code as an example ...

<?php
declare(strict_types=1);$fruits = array("butter" => 5.3, "meat" => 7, "banana" => 3);

function

<?php
function string_walk(&$string, $funcname, $userdata = null) {
for($i = 0; $i < strlen($string); $i++) {
$hack = $string{$i};
call_user_func($funcname, &$hack, $i, $userdata);
$string{$i} = $hack;
}
}

function

function

You can use following instead:

$result = array_map("trim", $array);

Here's how to lower-case all elements in an array:

<?php
$arr = array_map('strtolower', $arr);
?>

function indexArrayByElement($array, $element)

<?php
$output = array();
array_walk($input, 'gmapmark_reverse', $output);

function

<?php
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

$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");

foreach($fruits as $cls => $vls)

Results:

Array

<?php
function array_explore(array &$array, callable $callback)
{
array_walk($array, function(&$value, $key) use (&$array, $callback)
{
$callback($array, $key, $value);

if(

throw new

return

return

});

<?php
$array1 = test('array_walk');
$array2 = test('array_walk_list_each');
$array3 = test('array_walk_foreach1');
$array4 = test('array_walk_foreach2');var_dump($array1 == $array2, $array1 == $array3, $array1 == $array4);function array_walk_list_each(&$array, $function, $userData = null) {
while ( list($key, $value) = each($array) )
$function($array[$key], $key, $userData);
}function array_walk_foreach1(&$array, $function, $userData = null) {
foreach ($array as $key => &$value )
$function($value, $key, $userData);
}function array_walk_foreach2(&$array, $function, $userData = null) {
foreach ($array as $key => $value )
$function($array[$key], $key, $userData);
}

function

function

return

<?php function zip(&$data, $glue=': ')
{
if(!is_array($data)) {
throw new InvalidArgumentException('First parameter must be an array');
} array_walk($data, function(&$value, $key, $joinUsing) {
$value = $key . $joinUsing . $value;
}, $glue);
} $myName = 'Matthew Purdon';
$myEmail = 'matthew@example.com';
$from = "$myName <$myEmail>"; $headers['From'] = $from;
$headers['Reply-To'] = $from;
$headers['Return-path'] = "<$myEmail>";
$headers['X-Mailer'] = "PHP" . phpversion() . "";
$headers['Content-Type'] = 'text/plain; charset="UTF-8"'; zip($headers); $headers = implode("\n", $headers);
$headers .= "\n";

echo

<?php
$fruits = array("Lemony & Fresh","Orange Twist","Apple Juice");print_r($fruits);
echo '<br />';

function

<?php
array_walk($myArray, function(&$value, $key){
});
?>

<?php
$myArray = array(1, 2, 3, 4, 5);array_walk($myArray, function(&$value, $index){
if ($value > 0) $value *= 2;
});
?>

<?php
$names = array("D\'Artagnan", "Aramis", "Portos");
array_walk($names, function(&$n) {
$n = stripslashes($n);
});
?>

<?php
$array = array('foo' => 'bar', 'baz' => 'bat');array_walk($array, function($val,$key) use(&$array){
if ($val == 'bar') {
unset($array[$key]);
}
});var_dump($array);

<?php
$array1 = test('array_walk');
$array2 = test('array_walk_list_each');
$array3 = test('array_walk_foreach1');
$array4 = test('array_walk_foreach2');var_dump($array1 == $array2, $array1 == $array3, $array1 == $array4);function array_walk_list_each(&$array, $function, $userData = null) {
reset($array);
while ( list($key, $value) = each($array) )
$function($array[$key], $key, $userData);
}function array_walk_foreach1(&$array, $function, $userData = null) {
foreach ($array as $key => &$value )
$function($value, $key, $userData);
}function array_walk_foreach2(&$array, $function, $userData = null) {
foreach ($array as $key => $value )
$function($array[$key], $key, $userData);
}

function

function

return

<?phpfunction array_implode_prefix($outer_glue, $arr, $inner_glue, $prefix=false){
array_walk( $arr , "prefix", array($inner_glue, $prefix) );
return implode($outer_glue, $arr);
}

function

echo

<?php
echo '<pre>';
$a = [ 1, 2, 3, 4, 5, 6];
$c = [10,20,30,40,50,60];array_walk($a,
function(&$item, $key, $y) { $item += $y[$key];},
$c
);print_r($a);Array
(
[0] => 11
[1] => 22
[2] => 33
[3] => 44
[4] => 55
[5] => 66
)

<?php
array_walk($ids, create_function('&$val', '$val = trim($val);'));
?>

I just wanted to walk from the end to the beginning.

And to set allow_call_time_pass_reference to true in php.ini won't work, according to http://bugs.php.net/bug.php?id=19699 thus to work around:

<?php
array_walk($arrChnOut, create_function('&$v, $k, $arr_rtn', 'if ($k{0}!="_") {$arr_rtn[0]["_".$v[\'ID\']]=$v; unset($arr_rtn[0][$k]);}'), array(&$arrChnOut));
?>

Check out array_map().

http://php.net/array_map

It's all sorts of win.

For the record. I'm one of these people and after 15 years of php development I'm pleased to say that there's still things I'm learning. :) I just found out about array_map() myself...

<?php
function array_walk_protected(&$a,$s,$p=null)
{
if(!function_exists($s)||!is_array($a))
{
return false;
}

foreach(

function

$array = ['a'=>10, 'b'=>20];

$newArray = array_values(array_walk($array, 'fn'));

function fn(&$val,$key){

global $sequence;

$sequence [] = $val;

}

No need to concern about the place of the internal pointer for the baby array. You have now rewinded, 0 based new array, string key one instead.

If you want to add values with same key from two arrays :

<?php
function add(&$item,$key,$search) {
$item += (is_array($search))?((isset($search[$key]))?$search[$key]:0):0;
}$a = ["orange" => 2, "banana" => 3, "apple" => 1];
$b = ["orange" => 1, "apple" => 4];array_walk($c,"add",$b);

echo

<?php

$array

function

Prototype:

<?phpfunction arrayWalk(&$arry, $callback, $params=false) {
$P=array(""); $a=""; if($params !== false) { if(is_array($params)) { foreach($params as $par)
{ $P[]=$par; }
}
else { $P[]=$params; }
}

for(

class SomeVeryImportantClass

private function munge(&$value, &$key)

so...