array_walk()使用

2024-06-24 09:18

文章标签 使用 walk array

本文主要是介绍array_walk()使用，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

 bool  array_walk (  array &$array ,  callable $callback [,  mixed $userdata = NULL ] ) 

将用户自定义函数 funcname 应用到 array 数组中的每个单元。
array_walk() 不会受到 array 内部数组指针的影响。array_walk() 会遍历整个数组而不管指针的位置。

array_walk($array, callback, userdata);

	$array 输入的数组， callback($array的参数, 键名，$prefix)  $userdata 将被作为第三个参数传递给 callback prefix

测试环境 7.0.1

<?php

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

function test_alter(&$item1, $key, $prefix)   //注意这里第一个是取地址符，$prefix 表示为前缀
{$item1 = "$prefix: $item1";
}function test_print($item2, $key)
{echo "$key. $item2<br />\n";
}echo "Before ...:\n";
array_walk($fruits, 'test_print');

array_walk($fruits, 'test_alter', 'fruit');
echo "... and after:\n";
var_dump($fruits);
array_walk($fruits, 'test_print');

Before ...:
d. lemon
a. orange
b. banana
c. apple
... and after:
d. fruit: lemon
a. fruit: orange
b. fruit: banana
c. fruit: apple

$fruits = array("1" => "lemon", "2" => "orange", "3" => "banana", "4" => "apple");

function test_print($item2, &$key)
{++$key;
    echo "$key. $item2<br />\n";
}array_walk($fruits, 'test_print');
var_dump($fruits);exit;  array(4) { [1]=> string(5) "lemon" [2]=> string(6) "orange" [3]=> string(6) "banana" [4]=> string(5) "apple" }

key值没有变化，说明，array_walk   function中第二个方法中如果使用的key取地址符，key的值依然不变

Waring:

If the class is static:
array_walk($array, array('self', 'walkFunction'));
or
array_walk($array, array('className', 'walkFunction'));

Otherwise:
array_walk($array, array($this, 'walkFunction'));

array_walk 与匿名函数结合使用

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", $headers);
var_dump($headers);
exit;