如何通過在分層鍵的循環數組中訪問它來取消設置對象鍵 (php)

Question

我有一個 XML 對象

$xml = SimpleXMLElement Object
    (
        [a] => SimpleXMLElement Object
                    (
                        [b] => SimpleXMLElement Object
                                   (
                                       [c] => 'hey',
                                   ),
                     ),
    )

現在，我將所有鍵都放在數組中，我想取消設置最后一個鍵，即對象中的“c”

$temp = $xml;
$keys_arr = ['a', 'b', 'c'];
foreach($keys_arr => $key){
    $temp = $temp->$key;
}
unset($temp) // I want this to work like when we use this 'unset($xml->a->b->c);'

當我們打印 $temp 時：

print_r($temp);

輸出應該是：

SimpleXMLElement Object
        (
            [a] => SimpleXMLElement Object
                        (
                            [b] => SimpleXMLElement Object
                                       (
                                           // without '[c]' key
                                       ),
                         ),
        )

Answer 1

這是一種遞歸方法（與堆疊相反）：

代碼：（演示）

function recurse(&$object,$keys){  // modify the input by reference
    $key=array_shift($keys);
    if(isset($object->$key)){  // avoid trouble
        if(empty($keys)){
            unset($object->$key);  // remove at last key
        }else{
            recurse($object->$key,$keys);  // continue recursion
        }
    }
}

$xmlstring=<<<XML
    <root>
        <a>
            <b>
                <c>hey</c>
            </b>
        </a>
    </root>
XML;
$keys=['a','b','c'];

$xml=new SimpleXMLElement($xmlstring);
echo "Before: \n";
var_export($xml);
echo "\n----\nAfter:\n";

recurse($xml,$keys);  // modify input
var_export($xml);

輸出：

Before: 
SimpleXMLElement::__set_state(array(
   'a' => 
  SimpleXMLElement::__set_state(array(
     'b' => 
    SimpleXMLElement::__set_state(array(
       'c' => 'hey',
    )),
  )),
))
----
After:
SimpleXMLElement::__set_state(array(
   'a' => 
  SimpleXMLElement::__set_state(array(
     'b' => 
    SimpleXMLElement::__set_state(array(
    )),
  )),
))

---

這是我如何堆疊它以達到相同的結果： Demo

$mod=&$xml;               // modify $xml by reference
$keys=['a','b','c'];
$last=array_pop($keys);   // assuming the array will not be empty, the array will contain valid/existing object keys
foreach($keys as $key){   // iterate/traverse all remaining keys (e.g. 'a','b' because 'c' was popped off)
    $mod=&$mod->$key;     // overwrite $mod by reference while traversing
}
unset($mod->$last);       // unset the last object
var_export($xml);         // print modified $xml to screen

Answer 2

遍歷除最后一項之外的鍵數組，最后執行取消設置。 但是通過引用分配給 $temp ！！

$temp = &$xml;
$keys_arr = ['a', 'b', 'c'];
for($i,$size=count($keys_arr); $i<$size-1; $i++){
    $temp = &$temp->$keys_arr[$i];
}
unset($temp->$keys_arr[$i]);