从子数组（PHP）将数据推送到父数组

oddhotrod 发表于 Mysql

奇怪的：

我有很多棒球队，每个棒球队里都有一系列赛季。每个赛季内的获胜次数。我想统计一个团队的所有胜利，然后将此数字推入每个团队的数据中。我的最终目标是按照每个团队的总获胜次数来排序此主阵列。

我的问题是，我不知道如何将totalGamesWon统计信息推向团队数据的主要数组。

对于效率低下的编码，请提前致歉！如果有像我这样的新手有更好的方法可以做到这一点，那么我无所不能！

$teams = array(
  array (
    'teamName' => 'Yankees',
    'seasons' => array (
      array(
        'seasonName' => '2018 Regular Season',
        'wins' => 100
      ),
      array(
        'seasonName' => '2018 Playoffs',
        'wins' => 2
      )
    )
  ),
  array (
    'teamName' => 'Red Sox',
    'seasons' => array (
      array(
        'seasonName' => '2018 Regular Season',
        'wins' => 108
      ),
      array(
        'seasonName' => '2018 Playoffs',
        'wins' => 11
      )
    )
  ),
);

foreach ($teams as $team) {
  $totalGamesWon = 0;
  foreach ($team['seasons'] as $season) {
    $totalGamesWon += $season['wins'];
  }
  $team['totalGamesWon'] = $totalGamesWon;
}

echo $teams[0]['teamName'];       // outputs "Yankees"
echo $teams[0]['totalGamesWon'];  // should output "102". Instead, I get "Notice: Undefined index: totalGamesWon"

世界上最好的程序员：

只需更改$team为&$team，即可通过$team 按引用而不是按值传递：

foreach ($teams as &$team) {
   $totalGamesWon = 0;
   foreach ($team['seasons'] as $season) {
       $totalGamesWon += $season['wins'];
   }
   $team['totalGamesWon'] = $totalGamesWon;
}

默认情况下（$team）它通过值传递，这意味着它仅在范围内（在循环中）更改。因此，每次迭代都会设置$ team ['totalGameswon']的值，但实际的数组$ teams不会受到影响。

通过引用传递它时，当前已更改的项目（$team['totalGamesWon']）会更改实际数组中的值。

因此：（按值传递）

foreach ($teams as $key => $team) {
   $totalGamesWon = 0;
   foreach ($team['seasons'] as $season) {
       $totalGamesWon += $season['wins'];
   }
   $teams[$key]['totalGamesWon'] = $totalGamesWon;
}

和（通过引用传递）

foreach ($teams as &$team) {
   $totalGamesWon = 0;
   foreach ($team['seasons'] as $season) {
       $totalGamesWon += $season['wins'];
   }
   $team['totalGamesWon'] = $totalGamesWon;
}

会给你同样的结果。

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