[Creating a quiz system with mysql and php (correction of code)]

I keep having this response when I execute the index.php code - "undefined variable $ques". Please help me check the entire code. I have done my best to this extent. After checking please run it to be sure it works. I'm working on this project. I want to use it to build an app for reading and answering of quizes. 

[Creating a quiz system with mysql and php (correction of code)]

That is the MYSQL query. I keep getting the response from browser... "undefined variable " , when trying to execute the index.php code. 

[Creating a quiz system with mysql and php (correction of code)]

Database

A database needs to be created to store the information about questions, options and correct answers. So let's create a database using the following query. Here is a table 'questions' that contains all the quiz questions.

CREATE TABLE IF NOT EXISTS `questions` ( `qid` int(11) NOT NULL AUTO_INCREMENT, `question` varchar(150) NOT NULL, `is_enabled` int(11) NOT NULL, PRIMARY KEY (`qid`) ) ENGINE=MyISAM AUTO_INCREMENT=5 DEFAULT CHARSET=latin1;

 

INSERT INTO `questions` (`qid`, `question`, `is_enabled`) VALUES (1, 'Which function is used to reverse the order of elements in an array?', 1), (2, 'Which function is used to return character from the ASCII value?', 1), (3, 'Which function is used to check the existence of a constant?', 1), (4, 'Which function is used to return the last element of an array?', 1);

 

Here is a table 'quiz_options' that contains all the quiz options -

CREATE TABLE IF NOT EXISTS `quiz_options` ( `option_id` int(11) NOT NULL AUTO_INCREMENT, `qid` int(11) NOT NULL, `option` varchar(150) NOT NULL, `is_enabled` int(11) NOT NULL, PRIMARY KEY (`option_id`) ) ENGINE=MyISAM AUTO_INCREMENT=17 DEFAULT CHARSET=latin1;

 

INSERT INTO `quiz_options` (`option_id`, `qid`, `option`, `is_enabled`) VALUES (1, 1, 'array_rev()', 1), (2, 1, 'array_reverse()', 1), (3, 1, 'reverse()', 1), (4, 1, 'array_end()', 1), (5, 2, 'chr()', 1), (6, 2, 'ascii()', 1), (7, 2, 'asc()', 1), (8, 2, 'return_chr()', 1), (9, 3, 'define()', 1), (10, 3, 'const()', 1), (11, 3, 'defined()', 1), (12, 3, 'exist()', 1), (13, 4, 'end()', 1), (14, 4, 'arr_end()', 1), (15, 4, 'last()', 1), (16, 4, 'end()', 1);

 

At last, we create a table 'quiz_answer' for storing the correct answer of the quiz -

CREATE TABLE IF NOT EXISTS `quiz_answer` ( `qa_id` int(11) NOT NULL AUTO_INCREMENT, `qid` int(11) NOT NULL, `option_number` int(11) NOT NULL, PRIMARY KEY (`qa_id`) ) ENGINE=MyISAM AUTO_INCREMENT=5 DEFAULT CHARSET=latin1;

 

INSERT INTO `quiz_answer` (`qa_id`, `qid`, `option_number`) VALUES (1, 1, 2), (2, 2, 1), (3, 3, 3), (4, 4, 4);

 

 

[Creating a quiz system with mysql and php (correction of code)]

That is why I said I have not seen the one e he edited... 

[Creating a quiz system with mysql and php (correction of code)]

15 hours ago, gizmola said:

I don't know if you have a question here.  In the future post code using the code tag button.

Some things I did when fixing your post:

Your index.php had a number of errors in the way the form markup was rendered.  You were also missing a php block end brace.

When you have a class file like the one you have for Quiz, then name that file Quiz.php.  I didn't change that in your code, but you should follow that practice going forward.

You probably want to replace the code you had, with what I put into your post (which I edited heavily).

If you have an actual question, you can follow up in this thread.

I have not seen the one you corrected.

[Creating a quiz system with mysql and php (correction of code)]

Please I am having problem to execute the index.php code in the browser. I ask for your help to correct the code. 

[Creating a quiz system with mysql and php (correction of code)]

quizclass.php

First, we have taken variables for database credentials. Next, we have taken a constructor function for database connectivity code.

<?php

class Quiz {
    // Database credentials
    private $host = 'hostname';
    private $username = 'username';
    private $password = 'password';
    private $database = 'dbname';
    public $db;

    public function __construct()
    {
        if (!isset($this->db)) {
            // Connect to the database
            try {
                $this->db = new mysqli($this->host, $this->username, $this->password, $this->database);
            } catch (Exception $e) {
                $error = $e->getMessage();
                echo $error;
            }
        }
    }

    public function get_questions()
    {
        $select = "SELECT * FROM `questions` where is_enabled = '1' ";
        $result = mysqli_query($this->db, $select);
        return mysqli_fetch_all($result);
    }

    public function quiz_options($qid)
    {
        $select = "SELECT * FROM `quiz_options` where qid = '$qid' AND is_enabled = '1' ";
        $result = mysqli_query($this->db, $select);return mysqli_fetch_all($result);
    }
    
    public function answer($qid)
    {
        $select = "SELECT * FROM `quiz_answer` where qid = '$qid' ";
        $result = mysqli_query($this->db, $select);return mysqli_fetch_all($result);
    }
}

 

index.php

This is the main file that we will call in the browser. In this, we have imported the 'quizclass.php' and loop over the questions and options data. When the user submits the form, it will redirect to the 'score.php' page.

<html>
    <head>
        <title>PHP Multiple Choice Questions and Answers</title>
        <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
    </head>
    <body>
         <?php 
            include 'quizclass.php'; 
            $db = new Quiz(); 
            $quesions = $db->get_questions(); 
        ?>
        <div class="container">
            <h1>Multiple Choice Questions Answers</h1>
            <p>Please fill the details and answers the all questions-</p>
            <form action="score.php" method="post">
                <div class="form-group">
                    <?php 
                        foreach($quesions as $ques) { 
                            $options = $db->quiz_options($ques[0]);
                        }?> 
                        <h4><?php echo $ques[1]; ?></h4>
                        <div class="input-group-text" style="text-align: left; font-size: 18px;">
                        <ol>
                            <?php foreach($options as $option) {
                                echo "<li><input type='radio' name='".$option[2]."' value='".$option[1]."' required/> ".$option[3]."</li>"; 
                            }?> 
                        </ol>
                <div class="form-group">
                    <input type="submit" value="Submit" name="submit" class="btn btn-primary"/>
                </div>
            </form>
        </div>
    </body>
</html>

score.php

In this page, we collect the post data and calculate the score of the user. For this, we have imported the 'quizclass.php' database class file and compared the correct answer with the user's.

<?php
    include 'quizclass.php';
    $db = new Quiz();
    $score = 0;
    foreach ($_POST as $k=>$v) { 
        $answer = $db->answer($k);
        if ($answer[0][2] == $v) { 
            // option is correct 
            $score++; 
        } 
    } 
    $score = $score / 4 *100; 
    if($score < 50) { 
        echo '<h2>You need to score at least 50% to pass the exam.</h2>'; 
    } else { 
        echo '<h2>You have passed the exam and scored '.$score.'%.</h2>'; 
}