array_walk_recursive()

(PHP 5, PHP 7)

对数组中的每个成员递归地应用用户函数

说明

将用户自定义函数$callback应用到$array数组中的每个单元。本函数会递归到更深层的数组中去。

参数

输入的数组。

典型情况下$callback接受两个参数。$array参数的值作为第一个，键名作为第二个。

如果$callback需要直接作用于数组中的值，则给$callback的第一个参数指定为引用。这样任何对这些单元的改变也将会改变原始数组本身。$userdata

如果提供了可选参数$userdata，将被作为第三个参数传递给$callback。

返回值

成功时返回TRUE，或者在失败时返回FALSE。

范例

Example #1array_walk_recursive()例子

以上例程会输出：

a holds apple
b holds banana
sour holds lemon

注意上例中的键'sweet'并没有显示出来。任何其值为array的键都不会被传递到回调函数中去。

参见

• array_walk() 使用用户自定义函数对数组中的每个元素做回调处理
• callback类型的信息

Since this is only mentioned in the footnote of the output of one of the examples, I feel it should be spelled out:
* THIS FUNCTION ONLY VISITS LEAF NODES *
That is to say that if you have a tree of arrays with subarrays of subarrays, only the plain values at the leaves of the tree will be visited by the callback function. The callback function isn't ever called for a nodes in the tree that subnodes (i.e., a subarray). This has the effect as to make this function unusable for most practical situations.

If you are wanting to change the values of an existing multi-dimensional array, as it says above in the note, you need to specify the first argument as a reference. All that means is, be sure to precede the $item variable with an ampersand (&) as in the good_example below. 
Unfortunately the PHP example given doesn't do this. It actually took me a while to figure out why my function wasn't changing the original array, even though I was passing by reference. 
Here's the tip: Don't return any value from the function! Just change the value of $item that you passed in by reference. This is rather counter-intuitive since the vast majority of functions return a value.

Returning a value from your function does work if you pass by reference and modify $item before you return, but you will eat up memory very, very fast if you try it, even on an example as small as the one here.
One other silly thing you might try first is something like this:

[EDIT BY danbrown AT php DOT net: In a note added by 'FaustoFilho' on 17-MAY-2011, the following information was appended to this note.
[If you intend to use this] "function to extract the last key value of an array, don't forget to insert a currency sign ($) signal before '$output' at 7th line.
This value must be a variable, and if you forgot to assign this signal, your code won't work, displaying an error like this:
Parse error: syntax error, unexpected ')', expecting T_PAAMAYIM_NEKUDOTAYIM in /path/to/script.php on line 7."]

Example for the use of $userdata:
$userdata is the third parameter of the callback function.
The first parameter is $item, the second is $key, and the third one is $userdata.

generates
a beinhaltet Apfel ... Bio 
b beinhaltet Banane ... Bio
sauer beinhaltet Zitrone ... Bio

takes an array as the first argument, and functions as the other arguments. it applies those functions recursively to the array

To egingell at sisna dot com:
There is a small bug in your function, the following line should be changed:
From: if ($value != $saved_value || $saved_key != $key) {
Into: if ($value !== $saved_value || $saved_key !== $key) {
It's a nice function, because I was searching for something to change the keys of a multiple dimension array.

鹏仔微信 15129739599 鹏仔QQ344225443 鹏仔前端 pjxi.com 共享博客 sharedbk.com