php - 如何使用 array_walk 更改元素的值？

Question

如何使用 array_walk 更改元素的值？

例如，这是我的数组，

$items = array(
    0 => array( 
        "id" => "1",
        "title" => "parent 1",
       "children" => array()
        ),

    1 => array( 
        "id" => "2",
        "title" => "parent 2",
        "children" => array (
           0 => array( 
            "id" => "4",
            "title" => "children 1"
            ),
           1 => array( 
            "id" => "5",
            "title" => "children 2"
            ) 
        ),
   )
);

我可以用下面的这个来改变它，

function myfunction(&$item,$key)
{
    if($item['id'] === '1')
    {
        $item['title'] = 'hello world en';
    }   
}


array_walk($items,"myfunction");

print_r($items);

但是我有一个嵌套的 child ，我也想更改其中的值，如果我这样做会出错，

function myfunction(&$item,$key)
{
    if($item['id'] === '1')
    {
        $item['title'] = 'hello world en';
    }

    if($item['id'] === '4')
    {
        $item['title'] = 'hello world en';
    }


    foreach($item as $key => $value)
    {

        if(is_array($value))
        {
            myfunction($value,$key);
        }
    }

}

错误，

Notice: Undefined index: id in ...index.php on line xx

知道如果数组中有嵌套子项我该怎么办吗？

Answer 1

您可以通过递归调用回调函数来实现。我已经实现了带有闭包的示例，例如:

//replacement array:
$replace = [
  '1' => 'foo',
  '2' => 'bar',
  '5' => 'baz'
];

array_walk($items, $f=function(&$value, $key) use (&$f, $replace)
{
   if(isset($replace[$value['id']]))
   {
      $value['title'] = $replace[$value['id']];
   }
   if(isset($value['children']))
   {
      //the loop which is failing in question:
      foreach($value['children'] as $k=>&$child)
      {
         $f($child, $k);
      }
      //Proper usage would be - to take advantage of $f
      //array_walk($value['children'], $f);
   }
});

如您所见 - 您所需要的只是通过引用传递值并在回调中迭代它作为 foreach 的引用。