如何找到鍵是特定值的對象的索引？

Question

希望我說得對...

我怎么能找到ID = 68的索引？

我需要幫助創建一個返回索引2的函數...謝謝！

$posts = Array (
    [0] => stdClass Object
        (
            [ID] => 20
            [post_author] => 1
            [post_content] => 
            [post_title] => Carol Anshaw
        )

    [1] => stdClass Object
        (
            [ID] => 21
            [post_author] => 1
            [post_content] => 
            [post_title] => Marie Arana
        )

    [2] => stdClass Object
        (
            [ID] => 68
            [post_author] => 1
            [post_content] => 
            [post_title] => T.C. Boyle
        )

    [3] => stdClass Object
        (
            [ID] => 1395
            [post_author] => 1
            [post_content] => 
            [post_title] => Rosellen Brown
        )
)

Answer 1

1. 創建一個遍歷數組的簡單函數

2. 封裝它而不是讓它懸掛

3. 在粘貼社區的數據結構時， 請記住使用var_export而不是print_r

你可以做這么簡單的功能：

function getKeyForId($id, $haystack) {
    foreach($haystack as $key => $value) {
        if ($value->ID == $id) {
            return $key;
        }
    }
}

$keyFor68 = getKeyForId(68, $posts);

但是讓特定功能懸而未決是沒有意義的。 你可以這樣使用ArrayObject ：

class Posts extends ArrayObject {
    public function getKeyForId($id) {
        foreach($this as $key => $value) {
            if ($value->ID == $id) {
                return $key;
            }  
        }  
    }  
}

用法示例：

$posts = new Posts();

$posts[] = new StdClass();
$posts[0]->ID = 1;
$posts[0]->post_title = 'foo';


$posts[] = new StdClass();
$posts[1]->ID = 68;
$posts[1]->post_title = 'bar';


$posts[] = new StdClass();
$posts[2]->ID = 123;
$posts[2]->post_title = 'test';

echo "key for post 68: ";
echo $posts->getKeyForId(68);
echo "\n";
var_export($posts[$posts->getKeyForId(68)]);

輸出：

key for post 68: 1
stdClass::__set_state(array(
   'ID' => 68,
   'post_title' => 'bar',
))

Answer 2

function findIndexById($id, $array) {
    foreach($array as $key => $value) {
        if($value->ID == $id) {
            return $key;
        }
    }
    return false;
}

你可以像findIndexById(68, $array);一樣搜索它findIndexById(68, $array); 這將返回數組的索引，如果它發現否則為false。