PHP 重复列表

Question

这是我的代码，将所有类别列为列表项：

if ($xml) {
    foreach($xml->children() as $IRXML) {                                                                           // SHOW ONLY 5 NEWS ITEMS

        foreach($IRXML->children() as $newsrelease) {                                               // EACH NEWSRELEASE IS ONE SUBCHILD

            // echo "   <div class='news-image'>";
            // echo "<img src='/wp-content/themes/bby/images/news-story-01.jpg' alt=''>";
            // echo "</div>";

            $categories = $newsrelease->Categories;
            foreach($categories->children() as $category) {
                if ($category != "NA") {
                    echo "<li class='category ".$category."'>".$category."</li> ";
                }
            }

        }
    }

}

我想做的只是显示一个类别而不重复它。

Answer 1

$list_cache = array();

if ($xml)
{
    foreach($xml->children() as $IRXML) 

    foreach($IRXML->children() as $newsrelease) 
    {

        $categories = $newsrelease->Categories;

        foreach($categories->children() as $category)
        {
            if ($category != "NA")
            {
                $print_category = "<li class='category ".$category."'>".$category."</li> ";

                if( !in_array($print_category, $list_cache) )    //check if you've stored in previously in this array. In such case, in_array will return true. 
                {
                    $list_cache[] = $print_category;
                    echo $print_category;
                }
            }
        }
    }
}

查看文档中的 in_array 函数。

Answer 2

您的意思是您只想将每个显示一次吗？如果 .children() 返回同一个孩子两次，那可能是另一个问题；如果它不是您可以更改的内容并且这是您所看到的行为，您可以保留一个类别名称/ID 数组，在显示它们时追加，并在每次循环运行时写入输出之前检查数组是否有重复项。

Answer 3

假设在生成 XML 时无法消除重复项……那会更有效。

您可以在循环外部创建一个数组，然后检查是否已经看到某个类别。例子：

$categories = $newsrelease->Categories;
$seen_categories = array();
foreach($categories->children() as $category) {
    if ($category != "NA" && !in_array($category,$seen_categories)) {
        $seen_categories[]=$category;
        echo "<li class='category ".$category."'>".$category."</li> ";
    }
}