Question

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对该主阵列进行排序。

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。

对于无效的编码，请提前道歉！如果有一个更好的方式让像我这样的新手做到这一点，我将无所不在！

$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"

Answer 1

问题出在“ foreach（$ teams as $ team）”

foreach（）创建一个新变量$ team，其中每个周期都会复制$ teams []的值。

这意味着$ team是与$ teams []不同的变量。您在$ team中编写了totalGamesWon-在下一个循环中将被覆盖。 $ teams []保持不变。

尝试一下：

<?php

$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
        )
      )
    ),
  );

  $teamsCount = count($teams) ;

  for ($i = 0; $i < $teamsCount; $i++ ) 
  {
    $totalGamesWon = 0;
    foreach ($teams[$i]['seasons'] as $season) {
      $totalGamesWon += $season['wins'];
    }
    $teams[$i]['totalGamesWon'] = $totalGamesWon;
  }

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


die() ;
?>

Answer 2

只需将$team更改为&$team，就可以通过{strong>引用（而不是按值）传递$team：

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

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

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

所以：（通过值传递）

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

和（通过引用）

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

会给您相同的结果。

从子数组（PHP）中将数据推送到父数组

2 个答案: