Question

我正在寻找更好地理解如何使用while循环更有效地堆叠数组？

我有这个旧的数组，我需要迭代，爆炸每个，并创建一个多维数组。有没有更好的方法以编程方式执行此操作？

$cat[] = "Apparel, accessories & footwear"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s/Apparel"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s/Footwear"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s/Accessories";

foreach($cat as $cs){
    $ex = explode("/",$cs);
    $count = count($ex);
    if($count == 1){
        $category[$ex[0]] = array();
    }
    if($count == 2){
        $category[$ex[0]][$ex[1]] = array();
    }
    if($count == 3){
        $category[$ex[0]][$ex[1]][$ex[2]] = array();
    }
    if($count == 4){
        $category[$ex[0]][$ex[1]][$ex[2]][$ex[3]] = array();
    }
    if($count == 5){
        $category[$ex[0]][$ex[1]][$ex[2]][$ex[3]][$ex[4]] = array();
    }
}

问题在于，即使每次迭代最多只有3个数组，但这可能更多，但我不想手动创建if($count == x…我需要这是动态的。必须有更好的方法吗？

Answer 1

您需要使用&修饰符来set variables by reference而不是值。实际上，这意味着变量是另一个变量 - 对它的另一个引用。通过跟踪“根”对象并迭代由explode()生成的数组，您可以映射到$category数组以设置所需的多个级别。

$cat = array();
$cat[] = "Apparel, accessories & footwear"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s/Apparel"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s/Footwear"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s/Accessories";

// initialize array to track categories
$category = array();
// keep track of the root so we can reset it after each loop
$root = &$category;
foreach( $cat as $cs ){
    $exes = explode( "/", $cs );
    foreach ( $exes as $ex ){
        // get rid of spaces
        $ex = trim( $ex );
        // if this element isn't set at this level, add it
        if ( ! isset( $category[$ex] ) ){
            $category[$ex] = array();
        }
        // map down a level for the next loop
        $category = &$category[$ex];
    }
    // reset back to the $root for the next $cat
    $category = &$root;
}

var_dump( $category );

这将导致具有以下结构的数组，或者看到它running in this CodePad。

array(1) {
  ["Apparel, accessories & footwear"]=>
  array(1) {
    ["Men's"]=>
    array(3) {
      ["Apparel"]=>
      array(0) {
      }
      ["Footwear"]=>
      array(0) {
      }
      ["Accessories"]=>
      array(0) {
      }
    }
  }
}

Answer 2

未经测试的代码：

$cat[] = "Apparel, accessories & footwear"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s/Apparel"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s/Footwear"; 
$cat[] = "Apparel, accessories & footwear/Men&#39;s/Accessories";

foreach($cat as $cs){
    $ex = explode("/",$cs);
    $count = count($ex);

    $ptr = &$category;
    for( $i = 0; $i < $count; $i++){
       $ptr = &$ptr[$ex[$i]];
    } 

    $ptr = array();

}

编写多维数组php的更好方法

2 个答案: