Post radio button value in array to php file - php

Question

I'm trying to make a question paper. My code is like this:
<form action="check.php">
<span id="ques_id_12">Question 1</span>
<input type="radio" id="option_a_12" name="ques12[]" value="1">
<label for="option_a_12">Answer a</label>
<input type="radio" id="option_b_12" name="ques12[]" value="2">
<label for="option_b_12">Answer b</label>
<input type="radio" id="option_c_12" name="ques12[]" value="3">
<label for="option_c_12">Answer c</label>
<input type="radio" id="option_d_12" name="ques12[]" value="4">
<label for="option_d_12">Answer d</label>
<span id="ques_id_13">Question 2</span>
<input type="radio" id="option_a_13" name="ques13[]" value="1">
<label for="option_a_13">Answer a</label>
<input type="radio" id="option_b_13" name="ques13[]" value="2">
<label for="option_22">Answer b</label>
<input type="radio" id="option_c_13" name="ques13[]" value="3">
<label for="option_c_13">Answer c</label>
<input type="radio" id="option_d_13" name="ques13[]" value="4">
<label for="option_d_13">Answer d</label>
<span id="ques_id_14">Question 3</span>
<input type="radio" id="option_a_14" name="ques14[]" value="1">
<label for="option_a_14">Answer a</label>
<input type="radio" id="option_b_14" name="ques14[]" value="2">
<label for="option_b_14">Answer b</label>
<input type="radio" id="option_c_14" name="ques14[]" value="3">
<label for="option_c_14">Answer c</label>
<input type="radio" id="option_d_14" name="ques14[]" value="4">
<label for="option_d_14">Answer d</label>
<input type="submit">
</form>
The question is dynamic and above comes from a php and mysql code. I want to post the data to a php file where I can calculate the number of questions correct, number of questions wrong and number of questions attempted.
I'm confused how should I check the correct answers. $_POST[ans_a] would return ans_a from all questions. How can I distinguish all the questions and separately put them into array. Or should I change my way of arranging my dynamic code ?

Answer 1

Note what #RajdeepPaul said. Your answers are being exposed and posted along with the answers, so if you want any kind of security don't do this, and check for the answers in PHP..
$answers = ['ques12' => 4, 'ques13' => 3, 'ques14' => 2];
Now loop over all the answers. The keys in $answers are the same as in $_POST.

Answer 2

First of all, never put the correct answer as hidden input field in the HTML form. Anybody can see the source code and get the correct option for all the questions. Keep the correct answers(options) corresponding to particular questions in a table like this:
+-------------+----------------+
| question_id | correct_option |
+-------------+----------------+
| | |
Or, use an array like this:
$correct_options = array('ques_id_12' => 4, 'ques_id_13' => 3, 'ques_id_14' => 2);
So that later you could compare the correct answer with the user inputted option value.
Now comes to your question, you need to change the name attribute value of your checkbox elements like this,
name="ques_id_12" for all the checkbox options for question ID 12, name="ques_id_13" for all the checkbox options for question ID 13 etc.
Also, since you're sending bulk of data to the server with your form, you should use POST method instead of GET
So your form should be like this:
<form action="check.php" method="POST">
<span id="ques_id_12">Question 1</span>
<input type="radio" id="option_a_12" name="ques_id_12" value="1">
<label for="option_a_12">Answer a</label>
<input type="radio" id="option_b_12" name="ques_id_12" value="2">
<label for="option_b_12">Answer b</label>
<input type="radio" id="option_c_12" name="ques_id_12" value="3">
<label for="option_c_12">Answer c</label>
<input type="radio" id="option_d_12" name="ques_id_12" value="4">
<label for="option_d_12">Answer d</label>
<span id="ques_id_13">Question 2</span>
<input type="radio" id="option_a_13" name="ques_id_13" value="1">
<label for="option_a_13">Answer a</label>
<input type="radio" id="option_b_13" name="ques_id_13" value="2">
<label for="option_22">Answer b</label>
<input type="radio" id="option_c_13" name="ques_id_13" value="3">
<label for="option_c_13">Answer c</label>
<input type="radio" id="option_d_13" name="ques_id_13" value="4">
<label for="option_d_13">Answer d</label>
<span id="ques_id_14">Question 3</span>
<input type="radio" id="option_a_14" name="ques_id_14" value="1">
<label for="option_a_14">Answer a</label>
<input type="radio" id="option_b_14" name="ques_id_14" value="2">
<label for="option_b_14">Answer b</label>
<input type="radio" id="option_c_14" name="ques_id_14" value="3">
<label for="option_c_14">Answer c</label>
<input type="radio" id="option_d_14" name="ques_id_14" value="4">
<label for="option_d_14">Answer d</label>
<input type="submit">
</form>
And after form submission, you can use simple foreach loop to compare the user inputted option value with the correct option value for each question like this:
foreach($_POST as $question_id => $user_inputted_option){
// compare the user inputted option value with the correct option value
}
Update(1):
How I would know which questions have been answered and which have not ? And how would I pass the question id's ?
Let's say your question id array is like this:
$ques_ids = array('ques_id_12', 'ques_id_13', 'ques_id_14', 'ques_id_15', 'ques_id_16');
Then after form submission, you need to process your form like this:
$array_keys = array_keys($_POST); // all the user attempted question ids
foreach($ques_ids as $q_id){
if(in_array($q_id, $array_keys)){
// attempted question
$user_inputted_option_value = $_POST[$q_id];
// now compare the user inputted option value with the correct option value
}else{
// unattempted question
}
}
Sidenote: If you want to see the complete array structure, do var_dump($_POST);