I am making an online exam system in codeigniter - codeigniter

Question

I am developing an exam system in codeigniter. My database has table called questions which has 7 cols question, option1,2,3,4, correct answer and tag. I want to fetch and match results.
My view coding is
<form action="<?php echo base_url() ?>main/economics_validation" name ="f" method="post" accept-charset="utf-8">
<?php
foreach($eco as $economics)
{
?>
<li>
<h3><p>Q<?php echo $economics->id ?> <?php echo $economics->question; ?></p></h3>
<p><?php echo $economics->option1 ?>
<input type="radio" name="<?php echo $economics->id ?>" value="<?php echo $economics->option1 ?>"></p>
<p><?php echo $economics->option2 ?>
<input type="radio" name="<?php echo $economics->id ?>" value="<?php echo $economics->option2 ?>"></p>
<p><?php echo $economics->option3 ?>
<input type="radio" name="<?php echo $economics->id ?>" value="<?php echo $economics->option3 ?>"></p>
<p><?php echo $economics->option4 ?>
<input type="radio" name="<?php echo $economics->id ?>" value="<?php echo $economics->option4 ?>"></p>
</li>
<?php
}
?>
</ul>
</div>
and my controller coding is
public function economics_validation()
{
$result['d']=$this->model_db->calculate_marks();
$this->load->view('marks',$result);
}
and my model coding is
public function calculate_marks()
{
$query = $this->db->query("SELECT * FROM questions");
$a = $query->result();
$q2 = $this->db->get('questions');
$marks = 0;
foreach($a as $corr)
{
for($i = 1; $i <= $q2->num_rows();$i++)
{
if($corr->correct_answer == $this->input->post($i))
{
$marks = $marks + 1;
}
else
{
}
}
}
return $marks;
}
I'm unable to get the correct result. The problem is that it is telling incorrect answer as correct.

Answer 1

The function in your model needs some tweaks. Try this code.
public function calculate_marks()
{
$query = $this->db->query("SELECT * FROM questions");
$a = $query->result();
$marks = 0;
foreach($a as $corr)
{
if($corr->correct_answer == $this->input->post($corr->id))
{
$marks = $marks + 1;
}
}
return $marks;
}
That's all.