Question

I have the following code-

     <?php
                $input = array();
                for($i=0; $i<15; $i++)
                $input[]=$i;
                shuffle($input);

                $file="data.xml";
                $test= new SimpleXMLElement($file, null, true); ?>
                 <?php      

                          for($i=0; $i<5; $i++) {
                  ?> 

                <form action="submit.php" method="post" id="form">
                     <p id="ques"><?php echo $test->easy->question[$input[$i]]->ques?> </p>
                     <p id="option"><input type="radio" name="<?php echo $input[$i]?>" value="0" /><?php echo $test->easy->question[$input[$i]]->option[0]; ?></p>
                     <p id="option"><input type="radio" name="<?php echo $input[$i]?>" value="1" /><?php echo $test->easy->question[$input[$i]]->option[1]; ?></p>
                     <p id="option"><input type="radio" name="<?php echo $input[$i]?>" value="2" /><?php echo $test->easy->question[$input[$i]]->option[2]; ?></p>
                     <p id="option"><input type="radio" name="<?php echo $input[$i]?>" value="3" /><?php echo $test->easy->question[$input[$i]]->option[3]; ?></p>   
                 </form>
      <?php } ?>  

Now, in the submit page how do I use the input name $input[i] ?
$_POST[what do I write here?] ?

Answer 1

You initialized $input to contain 0..15 in a random order. Next you chose the first 5 entries via $i, so input[$i] will have a random number between 0 and 15. If you use this as a name attribute, you will not have a constant set of POST parameters to use.

So I suggest you do something like:

<form action="submit.php" method="post" id="form">
    <p id="ques"><?php echo $test->easy->question[$input[$i]]->ques?> </p>
    <input type="hidden" name="question" value="<?php echo $i; ?>">
    <p id="option"><input type="radio" name="q<?php echo $input[$i]?>" value="0" /><?php echo $test->easy->question[$input[$i]]->option[0]; ?></p>
    ....
    <p id="option"><input type="radio" name="q<?php echo $input[$i]?>" value="3" /><?php echo $test->easy->question[$input[$i]]->option[3]; ?></p>   
</form>

In the submit page read $_POST['question'], this gives you back your $i, then read $_POST["q$i"]