Php 初始化多维数组

我试图呈现mysql查询中的值，并将它们插入到多维数组中。我能够创建数组并将查询中的所有值插入数组

当数据库中不存在值并且我尝试回显数组设置时，就会出现问题。我得到以下错误：

Undefined offset: 2 

如果我让你知道我的意思可能会更容易

我的类包含许多动态回显设置值的函数 i、 e

上述值是通过以下查询中的值的动态呈现设置的：

while ($row = mysqli_fetch_array ($results, MYSQLI_ASSOC)) 
        {
            $this->answers[$row['period_id']][] =  $row['question_one'];

            $this->answers[$row['period_id']][] =  $row['question_two'];
        } 

只要数据库中存在值，此功能就可以工作。所以，我需要一种初始化数组的方法

我试过这样做

$this->answers = $this->theResponseArray();



public function theResponseArray()
    {
        return $array = array (
                    1  => array ( 
                                    0 => null, 
                                    1 => null, 
                                       ),
                    2 => array (
                                    0 => null, 
                                    1 => null,
                                       ),
                    3  => array (
                                    0 => "", 
                                    1 => "",
                                       ),
                   3  => array (
                                    0 => "", 
                                    1 => "",
                                       )
                  ); 
    }

但所发生的一切是，它将整个数组呈现为null，并阻止将新值放入数组中

更新

我已将整个代码放在小提琴上：

---

您可以通过isset检查数组中的值是否存在，然后对其执行某些操作，例如：

public function questionOne()
{
  if (isset($this->answers[$row['period_id']]['question_one']) {
    return  $this->answers[$row['period_id']]['question_one'];
  } else {
    return 'no question'; //or '', or whatever
  }
} 

编辑：

getQuestionWeekXyz函数唯一不同的地方是周数，所以应该将它放在一个地方。然后，您可以使用foreach浏览周表中的问题：

public function getQuestionByWeek($weekNo) {
    $result = '';
    //if there are no questions for this week
    if (!isset($this->answers[$weekNo]) || !is_array(this->answers[$weekNo])) {
        return $result; 
    }

    $result .= "<form action='index.php?view=$this->postDestination' method='post' >";

    foreach ($this->answers[$weekNo] as $questionNumber => $questionText) {
        $questionNumber++;
        $result .= "<p> 
                        Question Week {$this->numberToString($weekNo)}:  <textarea  name='cycleWeekQuestion{$this->numberToString($questionNumber)}' cols='$this->col' rows='$this->row' style='font-family: Tahoma; font-size: 12pt' />{$questionText}</textarea>
                    </P>";
    }
    $result .= "<input type='hidden' name='cycleWeekId' value='{$weekNo}'>
                    <span class='hideSubmit'><input type='submit'  name='submit'  size='20'  style='font-family: Tahoma; width: 200px; height: 25pt; font-size: 14pt' value='Submit'></span>
                </form>";

    return $result;
}

public function numberToString($number) 
{
    switch($number) {
        case 1: return 'One';
        case 2: return 'Two';
        case 3: return 'Three';
        case 4: return 'Four';
    }
    return $number;
}

public function questionsWeekOne()
{
    return $this->getQuestionByWeek(1);
}        

public function QuestionsWeekTwo()
{
   return $this->getQuestionByWeek(2);
}

public function QuestionsWeekThree()
{
   return $this->getQuestionByWeek(3);
}

public function QuestionsWeekFour()
{
     return $this->getQuestionByWeek(4);
}

---

你好，斯梅戈尔。谢谢你的回复。我希望能找到一个更干净的办法来解决这个问题。例如，一个函数可能有10个问题。我不能做，如果设置了10个问题，如果你发布这个案例的完整代码，我可以告诉你更好的方式。嗨，斯梅戈尔。我已经发布了完整的代码：嗨，保罗，我已经编辑了我的答案，你应该替换代码中的那些函数。嗨，斯梅戈尔。非常感谢你。我现在正在经历它。这是一种更为优雅的辩护方式。非常感谢你

public function getQuestionByWeek($weekNo) {
    $result = '';
    //if there are no questions for this week
    if (!isset($this->answers[$weekNo]) || !is_array(this->answers[$weekNo])) {
        return $result; 
    }

    $result .= "<form action='index.php?view=$this->postDestination' method='post' >";

    foreach ($this->answers[$weekNo] as $questionNumber => $questionText) {
        $questionNumber++;
        $result .= "<p> 
                        Question Week {$this->numberToString($weekNo)}:  <textarea  name='cycleWeekQuestion{$this->numberToString($questionNumber)}' cols='$this->col' rows='$this->row' style='font-family: Tahoma; font-size: 12pt' />{$questionText}</textarea>
                    </P>";
    }
    $result .= "<input type='hidden' name='cycleWeekId' value='{$weekNo}'>
                    <span class='hideSubmit'><input type='submit'  name='submit'  size='20'  style='font-family: Tahoma; width: 200px; height: 25pt; font-size: 14pt' value='Submit'></span>
                </form>";

    return $result;
}

public function numberToString($number) 
{
    switch($number) {
        case 1: return 'One';
        case 2: return 'Two';
        case 3: return 'Three';
        case 4: return 'Four';
    }
    return $number;
}

public function questionsWeekOne()
{
    return $this->getQuestionByWeek(1);
}        

public function QuestionsWeekTwo()
{
   return $this->getQuestionByWeek(2);
}

public function QuestionsWeekThree()
{
   return $this->getQuestionByWeek(3);
}

public function QuestionsWeekFour()
{
     return $this->getQuestionByWeek(4);
}