PHP多维数组键搜索

Question

So, I have multidimensional array (for example):

array[1][22]['name']
array[1][33]['name']
array[2][44]['name']
array[3][55]['name']

I know last array key(it's ID) (for example - [44]), how can I find value of [name] for known key?

In my guess I need something like array_search, but for key and in multidimensional array...

Answer 1

Here's a simple way with PHP >= 5.5.0. This assumes there is only one key 44 in the array:

echo array_column($array, 44)[0]['name'];
// or
echo current(array_column($array, 44))['name'];

Earlier versions:

foreach($array as $k => $v) { if(isset($v[44])) echo $v[44]['name']; }

Answer 2

You are better off changing your array structure:

$array = [
  22 => [ 'name' => 'A'],
  33 => [ 'name' => 'B'],
  44 => [ 'name' => 'C'],
  55 => [ 'name' => 'D'],
];

and simply write

$array[44]['name']

Answer 3

Wouldn't it be better to optimize your array for this search, for instance build another one with IDs as keys and references to the data as values?

When building your array you could:
$IDsIndex = array();
foreach(...) {
    $IDsIndex[$ID] = &$data;
}

and then:

$IDsIndex[44]['name'];

Answer 4

I have a function that seems to work for me. Let me know if you find it lacking. Note: It has not been tested for performance on massive arrays or objects.

function arrayKeySearch(array $haystack, string $search_key, &$output_value, int $occurence = 1){
    $result             = false;
    $search_occurences  = 0;
    $output_value       = null;
    if($occurence < 1){ $occurence = 1; }
    foreach($haystack as $key => $value){
        if($key == $search_key){
            $search_occurences++;
            if($search_occurences == $occurence){
                $result         = true;
                $output_value = $value;
                break;
            }
        }else if(is_array($value) || is_object($value)){
            if(is_object($value)){
                $value = (array)$value;
            }
            $result = arrayKeySearch($value, $search_key, $output_value, $occurence);
            if($result){
                break;
            }
        }
    }
    return $result;
}