PHP 創建索引數組與關聯數組

Question

我在下面調用 getTeams function 以獲得一個簡單的團隊名稱列表，但如果沒有兩步過程，我無法讓它工作。 如果我使用

function getTeams($teams){
      
    foreach ($teams as $team) {
         $team = $team['team'];
         $teamNames[] = $team['displayName'];            
    }
    return $teamNames;      
} 

看起來它正在創建一個關聯數組，其中鍵是從 0 開始的數字？

我可以使它工作使用

function getTeams($teams){
      
    foreach ($teams as $team) {
         $team = $team['team'];
         $teamNames[] = $team['displayName'];        
    }
    
    for ($i= 0; $i < count($teamNames); $i++){
        $teamNames2[$teamNames[$i]]=$teamNames[$i]; 
    }
    return $teamNames2;
        
}

我認為這可能是因為第一個數組是關聯數組，而第二個數組是創建索引數組？ 這個思維過程正確嗎？ 如果是這樣，在 foreach 循環中創建索引數組的正確方法是什么？

Answer 1

不知道你的數組：如果你想創建一個關聯數組，你應該給它的元素一個鍵。 所以而不是

function getTeams($teams){
      
    foreach ($teams as $team) {
         $team = $team['team'];
         $teamNames[] = $team['displayName'];            
    }
    return $teamNames;      
} 

代碼在哪里

$teamNames[]

將始終向您的數組添加索引條目。

如果您想要關聯條目，請改用鍵。 就像是

function getTeams($teams){

    foreach ($teams as $team) {
         $team = $team['team'];
         $teamNames[$team['key']] = $team['displayName'];            
    }
    return $teamNames;      
} 

$teamNames現在應該返回一個關聯數組

Answer 2

您可以使用array_column()來提取數據，並且使用array_combine()來進行關聯。

以下代碼將生成與第二個getTeams()相同的 output ：

$teams = [ // Sample data
    ['team' => ['displayName' => 'a']],
    ['team' => ['displayName' => 'b']],
    ['team' => ['displayName' => 'c']],
    ['team' => ['displayName' => 'd']],
];

// Extract display names
$teams = array_column(array_column($teams, 'team'), 'displayName');
// Make is associative
$teams = array_combine($teams, $teams);
var_dump($teams);

Output：

array(4) {
  ["a"] => string(1) "a"
  ["b"] => string(1) "b"
  ["c"] => string(1) "c"
  ["d"] => string(1) "d"
}