php - 未选择单选按钮时未定义的数组键

Question

未选择单选按钮时我的代码有问题（在图片上）：图片在这里

这是我的代码（错误在第 123 和 124 行）

           <?php 
$Questions = array(
    1 => array(
        'Question' => '1. CSS stands for',
        'Answers' => array(
            'A' => 'Computer Styled Sections',
            'B' => 'Cascading Style Sheets',
            'C' => 'Crazy Solid Shapes'
        ),
        'CorrectAnswer' => 'B'
    ),
    2 => array(
        'Question' => '2. What is the Capital of the Philippines',
        'Answers' => array(
            'A' => 'Cebu City',
            'B' => 'Davao City',
            'C' => 'Manila City'
        ),
        'CorrectAnswer' => 'C'
    )
);

if (isset($_POST['answers'])){
    $Answers = $_POST['answers']; // Get submitted answers.

    // Now this is fun, automated question checking! ;)

    foreach ($Questions as $QuestionNo => $Value){
        // Echo the question
        echo $Value['Question'].'<br />';

        if ($Answers[$QuestionNo] != $Value['CorrectAnswer']){
             echo 'You answered: <span style="color: red;">'.$Value['Answers'][$Answers[$QuestionNo]].'</span><br>'; // Replace style with a class
             echo 'Correct answer: <span style="color: green;">'.$Value['Answers'][$Value['CorrectAnswer']].'</span>';
        } else {
            echo 'Correct answer: <span style="color: green;">'.$Value['Answers'][$Answers[$QuestionNo]].'</span><br>'; // Replace style with a class
            echo 'You are correct: <span style="color: green;">'.$Value['Answers'][$Answers[$QuestionNo]].'</span>'; @$counter++;

        }

        echo '<br /><hr>'; 
                                if (@$counter=="") 
                                { 
                                $counter='0';
                                $results = "Your score: $counter/2"; 
                                }
                                else 
                                { 
                                $results = "Your score: $counter/2"; 
                                }
            }                           echo $results;
} else {  
?>
    <form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post" id="quiz">
    <?php foreach ($Questions as $QuestionNo => $Value){ ?>

        <h3><?php echo $Value['Question']; ?></h3>
        <?php 
            foreach ($Value['Answers'] as $Letter => $Answer){ 
            $Label = 'question-'.$QuestionNo.'-answers-'.$Letter;
        ?>
        <div>
            <input type="radio" name="answers[<?php echo $QuestionNo; ?>]" id="<?php echo $Label; ?>" value="<?php echo $Letter; ?>" />
            <label for="<?php echo $Label; ?>"><?php echo $Letter; ?>) <?php echo $Answer; ?> </label>
        </div>
        <?php } ?>

    <?php } ?>

该代码有效，但是当没有选择单选按钮时，我在照片“警告：未定义的数组键”中得到错误。选择单选按钮后，一切正常。

if ($Answers[$QuestionNo] != $Value['CorrectAnswer']){
             echo 'You answered: <span style="color: red;">'.$Value['Answers'][$Answers[$QuestionNo]].'</span><br>'; // Replace style with a class
             echo 'Correct answer: <span style="color: green;">'.$Value['Answers'][$Value['CorrectAnswer']].'</span>';
        } else {
            echo 'Correct answer: <span style="color: green;">'.$Value['Answers'][$Answers[$QuestionNo]].'</span><br>'; // Replace style with a class
            echo 'You are correct: <span style="color: green;">'.$Value['Answers'][$Answers[$QuestionNo]].'</span>'; @$counter++;

        }

这里是123和124线。

标签： php