如何在foreach迭代中修改多维数组的子元素

Question

我正在尝试修改多维数组的每个数组元素中第一个子元素的内容，但是，如果我通过引用传递所述元素，则会收到一个错误，即“&”不是预期的。我是否需要放弃 foreach ($arr as list ()) 语法并恢复为标准 for 循环并使用计数器变量进行访问？

foreach ($transactions as list(&$student, &$tyID)) {

    $query = "SELECT $column
              FROM student
              WHERE stUserID=$student";

    if ($stmt = mysqli_prepare($link, $query)) {
        mysqli_stmt_execute($stmt);

        mysqli_stmt_bind_result($stmt, $userHID);

        while (mysqli_stmt_fetch($stmt)) {
            $student = $userHID;
            $tyID = $transType[$tyID];
        }

        mysqli_stmt_close($stmt);
    }
}

编辑：更新代码，我实际上需要修改 transactions 数组中每个数组的前两个子元素。

Answer 1

为什么不能这样呢？假设键与列表变量相同

foreach ($transactions as &$transaction) {

    $query = "SELECT {$column}
              FROM student
              WHERE stUserID={$transaction['student']}";

    if ($stmt = mysqli_prepare($link, $query)) {
        mysqli_stmt_execute($stmt);

        mysqli_stmt_bind_result($stmt, $userHID);

        while (mysqli_stmt_fetch($stmt)) {
            $transaction['student'] = $userHID;
            $transaction['tyID'] = $transType[$transaction['tyID']];
        }

        mysqli_stmt_close($stmt);
    }
}