PHP Exam

[darylr]

Hi all,

Im having huge difficulties creating code for an exam. Basically, in my mysql db I have the following fields;

ID | Question | Ans1 | Ans2 | Ans3 | Correctans

I want 20 questions to appear on the test, each multiple choice. I've been working for hours now trying to get it to work, but all my methods have been to no avail (Im still a bit of a newbie). I searched these forums and found some code which I've now adapted for my test.

The questions display, but the corrections are wrong. No matter what, it always displays at the end that 20 questions were answered incorrectly, and just echos the 0 that $correct has. See code below;

$db = mysql_connect("localhost", "myusername", "mypass");
mysql_select_db("mydbname",$db); 

if ($useraction != 'checkit') {

$query = "select * from entrytest ORDER by RAND() LIMIT 20";
$result = mysql_query($query, $db);

$qnum = 0;

print "<FORM ACTION='$PHP_SELF' METHOD='post'><BR>\n";

while ($row = mysql_fetch_array($result)) {

$question_formfield = 'Q' . $qnum;

print "Q. <b>".$row['question']."</b><BR>\n";
print "<INPUT TYPE='radio' NAME='$question_formfield' VALUE='A'>".$row['ans1']."<BR>\n";
print "<INPUT TYPE='radio' NAME='$question_formfield' VALUE='B'>".$row['ans2']."<BR>\n";
print "<INPUT TYPE='radio' NAME='$question_formfield' VALUE='C'>".$row['ans3']."<P><P>\n";

$questionkey .= $row['id'] . ',';

$qnum++;

}

print "<INPUT TYPE='hidden' NAME='qkey' VALUE='$questionkey'>\n";
print "<INPUT TYPE='hidden' NAME='useraction' VALUE='checkit'>\n";
print "<INPUT TYPE='submit' VALUE='Check Test'>\n";
print "</FORM><br>\n";

}
// check the answeres on the form
else {

$correct = 0;
$incorrect = 0;

// load answers into array so we don't overwork the db
$query = "select * from entrytest";
$result = mysql_query($query, $db);
while ($row = mysql_fetch_array($result)) {
$answer_array['id'] = $row['correctans'];
}

// explode question id list from hidden
// form field into an array we can use
$questionkey = explode (',' , $qkey);

// now read through the form questions and check answers
$qnum = 0;
$question_formfield = 'Q' . $qnum;

while (isset(${$question_formfield})) { // note how we use a var-vars here!

if (${$question_formfield} == $answer_array[$questionkey[$qnum]]) {
$correct++;
}
else {
$incorrect++;
}

$qnum++;
$question_formfield = 'Q' . $qnum;
}


print "You ansered $correct questions correctly and $incorrect questions incorrectly.";
}


if($correct > 16) { echo "<br><br>Well done you passed"; }
else { echo "<br><br>You failed"; }

Im not familiar with the following code, which I think is the line that isnt registering right;

if (${$question_formfield} == $answer_array[$questionkey[$qnum]]) {
$correct++;
}

Can anyone help? 🙂

Thanks,

[masonbarge]

Okay, first off when you explode

$questionkey .= $row['id'] . ','; 

you are going to get 21 elements in the array due to the final comma, so just to be neat let's delete the last element (which will be null)

$questionkey = explode (',' , $qkey);
unset ($questionkey[20]);

Okay this array is correct now.

On second thought, that is going to cause confusion, so let's change the array so that it is exactly correct. So delete the unset line and instead modify

$questionkey .= [B] ',' . $row['id'][/B];
*  *  * 
$questionkey = explode (',' , $qkey);
array_shift($questionkey);  // remove first element of array and shift key numbers up one spot

and while we're at it let's spell "answers" and "answered" correctly :mad: Pretty sloppy for a test.

That's a lot neater. Our array is 0-19 for the 20 actual lines. Now let's print a question number before each question

$qno = ($qnum + 1);
print "Question #" . $qno . ': ' . "<b>".$row['question']."</b><BR>\n";

Next, the question sheet prints out "you failed". This is pretty easy to fix. We move a bracket to put the "you failed" if clause inside the checkit "if". So from this

 print "You ansered $correct questions correctly and $incorrect questions incorrectly.";
}
if($correct > 16) { echo "<br><br>Well done you passed"; }
else { echo "<br><br>You failed"; }

To this

 	print "You answered $correct questions correctly and $incorrect questions incorrectly.";
	if($correct > 16) { 
		echo "<br><br>Well done you passed";
	} else { 
		echo "<br><br>You failed";
	} 
} 

This would have been obvious if the code was neater, i.e. the internal "if" clauses were indented. (LOL, I promise -- no more "neatness counts" lectures -- I know you didn't write this. I'm just naturally sloppy and I have to ride myself constantly.)

I see a couple of major problems here. Not being a genius, I'm going to add a lot of "print_r" and/or "var_dump" so that I can see what is going on. This clarifies the problem, which is that the "correct answers" from the database don't match the real-life correct answers.

Gah. We are generating a random order SELECT and then comparing it to a different SELECT. I'm just going to give up on the example and rewrite it.

---

Here's what I came up with. This is a draft and it's very bloated, but it works as intended, including the hard part, the RAND() shuffle (which actually is nice in that it prevents one easy form of cheating). The biggest problem I had in this was keeping the one-page structure, because it was hard to figure out how to pass the variables from one side of an "if" clause to another. I did this by attaching the values to a hidden form button.

If you want to use this "as is", you need to redo the $db connection stuff. I always put the data connection information along with a stripslashes function and then put the entire file outside the "public.html" directory.

Notice I changed the "corectans" field from an identical string to a SET field with choices 'a','b','c'

I have also added a seventh database table, 'explanation', and I'm going to put in a functionality to display information about wrong answers.

My working version of this is at Daily Health Report Trivia Quiz

<?php //<!-- TRIVIA QUIZ -->

include("./../../mysql_trivia_user_connect.php");

if ($useraction != 'checkit') {
$answer = array();
$question = array();
$qnum = array();
$orgid = array();
$i = 0;
$query = "SELECT * from entrytest ORDER by RAND() LIMIT 20";
$result = mysql_query($query, $db);

while ($row = mysql_fetch_array($result, MYSQL_BOTH)) {
	$answer[$i] = $row[5];
	$question[$i] = $row['question'];
	$qnum[$i] = $i;
	$orgid[$i] = $row['id'];
	$ans1[$i] = $row['ans1'];
	$ans2[$i] = $row['ans2'];
	$ans3[$i] = $row['ans3'];	
	$i++;
}
	$user_answer = array();
	$i = 0;
	$j = 1;
	print "<FORM ACTION='$PHP_SELF' METHOD='post'><BR>\n";
	while ($j <= 20)  {
		print "Question #" . $j . ': ' . "<b>".$question[$i]."</b><BR>\n";
		print "<INPUT TYPE='radio' NAME='user_answer[" . $i . "]'  VALUE='a'>".$ans1[$i]."<BR>\n";
		print "<INPUT TYPE='radio' NAME='user_answer[" . $i . "]'  VALUE='b'>".$ans2[$i]."<BR>\n";
		print "<INPUT TYPE='radio' NAME='user_answer[" . $i . "]'  VALUE='c'>".$ans3[$i]."<P><P>\n";
		$i++;
		$j++;
	}

//print "<INPUT TYPE='hidden' NAME='qkey' VALUE='$questionkey'>\n";	
$ii=0;
while ($ii<=19) {
	print "<input type='hidden' name='answer[$ii]' value='$answer[$ii]'>\n";
	print "<input type='hidden' name='orgid[$ii]' value='$orgid[$ii]'>\n";
	$ii++;
} 
print "<INPUT TYPE='hidden' NAME='useraction' VALUE='checkit'>\n"; 
print "<INPUT TYPE='submit' NAME='submitted' VALUE='Check Answers'>\n";
print "</FORM><br>\n";

} else {     // <!-- if submitted, check the answers on the form -->

$i=0;
$correct = 0;
$incorrect = 0;
foreach ($_POST['orgid] as $k =>$v)  {
$orgid[$k] = $v;
}
print_r ($orgid);
$k = 0;
$m = 0;
$query = "SELECT 'correctans','explanation' FROM entrytest WHERE 'id' IN \"$orgid\"";
$result = mysql_query($query);
while ($row = mysql_fetch_array($result))  {
	echo $row['explanation'];
}
	while ($k <= 19)  {
		if ($_POST['user_answer'][$k] == $answer[$k])  {
			$correct++;
		} else {
			$incorrect++;
		}
		$k++;
	}
echo "<br><br>";
print "You answered $correct questions correctly and $incorrect questions incorrectly.";
if($correct > 16)  { 
	echo "<br><br>Well done you passed";
} elseif  { ($correct > 10) 
	echo "<br><br>You fell a bit short of a passing grade this time.  We're sure you'll do better after you brush up
	on your molecular biophysics.";
} else {
		echo "<br><br>Well you made a mess of that. Try reading a book instead of skateboarding tomorrow.";
} 
echo "Here are the questions you missed:<br>"

} 
?>

There are a few lines that seem out of place, because I have already done a little preparatory to echoing an explanation for each incorrect answer. Actually this is a working draft with the incomplete executable scraps removed so that it will function -- I just thought you'd like to go ahead and get an answer, and maybe get started working to get this functional on your db connection.

I think the database is identical to yours except for the 'correctans' field. Once you change that and get the connection set up it should work as written with your db.

I actually had fun doing this and figuring out how to pass the values from one case of the "if" conditional to the other. As a side benefit I have a functional trivia quiz that is completely inappropriate for the website I used to test it 😉

[masonbarge]

Sorry, there is a scrap of executable code that needs to come out before it works:

foreach ($_POST['orgid] as $k =>$v)  {
	$orgid[$k] = $v;
	}
	print_r ($orgid);
	$k = 0;
	$m = 0;
	$query = "SELECT 'correctans','explanation' FROM entrytest WHERE 'id' IN \"$orgid\"";
	$result = mysql_query($query);
	while ($row = mysql_fetch_array($result))  {
		echo $row['explanation'];
	}

This is (obviously) the beginning of the explanation code.

If anyone knows how to limit SELECT results to an external array element, please let me know. I'd rather do it in the query but if I can't figure out how, I'll have to do it in the php which is going to be more bloat.

[darylr]

Hi Masonbarge,

Thanks a million for that, really appreciate it!

However, when it corrects the questions, it only now displays one correct answer no matter how many are correctly selected

"You answered 1 questions correctly and 19 questions incorrectly."

Any idea what could be gone wrong? Ive used your code above and took out the explanation code above.

Thanks,

[masonbarge]

I just don't know what it could be. Post your code.

Here's my current version. It's all done except the explanations are out of order, so maybe you can recopy it and just insert your db connection.

Oh yeah, I had to add the correct answer text back to the table as an eight (last) TINITEXT field. This won't work right unless you do that, but with cut and paste it takes about 30 seconds.

Put a funny picture in the <img> slot, I've got a confused kid cartoon 🙂

		
 <!-- PHP -->
<?php  //<!-- TRIVIA QUIZ -->

include("./../../mysql_trivia_user_connect.php");

if ($useraction != 'checkit') {
$answer = array();
$question = array();
$qnum = array();
$orgid = array();
$i = 0;
$query = "SELECT * from entrytest ORDER by RAND() LIMIT 20";
$result = mysql_query($query, $db);

while ($row = mysql_fetch_array($result, MYSQL_BOTH)) {
	$answer[$i] = $row[5];
	$question[$i] = $row['1'];
	$qnum[$i] = $i;
	$orgid[$i] = $row['id'];
	$ans1[$i] = $row[3];
	$ans2[$i] = $row[4];
	$ans3[$i] = $row[5];	
	$i++;
}
	$user_answer = array();
	$i = 0;
	$j = 1;
	print "<FORM ACTION='$PHP_SELF' METHOD='post'><BR>\n";
	while ($j <= 20)  {
		print "Question #" . $j . ': ' . "<b>".$question[$i]."</b><BR>\n";
		print "<INPUT TYPE='radio' NAME='user_answer[" . $i . "]'  VALUE='a'>".$ans1[$i]."<BR>\n";
		print "<INPUT TYPE='radio' NAME='user_answer[" . $i . "]'  VALUE='b'>".$ans2[$i]."<BR>\n";
		print "<INPUT TYPE='radio' NAME='user_answer[" . $i . "]'  VALUE='c'>".$ans3[$i]."<P><P>\n";
		$i++;
		$j++;
	}

//print "<INPUT TYPE='hidden' NAME='qkey' VALUE='$questionkey'>\n";	
$ii=0;
while ($ii<=19) {
	print "<input type='hidden' name='answer[$ii]' value='$answer[$ii]'>\n";
	print "<input type='hidden' name='orgid[$ii]' value='$orgid[$ii]'>\n";
	$ii++;
} 
print "<INPUT TYPE='hidden' NAME='useraction' VALUE='checkit'>\n"; 
print "<INPUT TYPE='submit' NAME='submitted' VALUE='Check Answers'>\n";
print "</FORM><br>\n";

} else {     // <!-- if submitted, check the answers on the form -->

$i=0;
$correct = 0;
$incorrect = 0;
foreach ($_POST['orgid'] as $k =>$v)  {
$orgid[$k] = $v;
}

$k = 0;
$m = 0;
	while ($k <= 19)  {
		if ($_POST['user_answer'][$k] == $answer[$k])  {
			$correct++;
			unset ($_POST['user_answer'][$k]);
			unset ($orgid[$k]);
		} else {
			$incorrect++;
		}
		$k++;
	}
echo "<br><br>";
print "You answered $correct questions correctly and $incorrect questions incorrectly.<br>";
if($correct > 16)  { 
	echo "<br><br>Well done! You passed with flying colors. I hope you went outside today and got some fresh air and exercise.<br><br>";
} elseif   ($correct > 10) {
	echo "<br><br>You fell a bit short of a passing grade this time.  We're sure you'll do better after you brush up
	on your molecular biophysics.<br><br>";
} else {
		echo "<br><br>Well you made a mess of that. Try reading a book instead of skateboarding tomorrow.<br><br>";
} 
echo "<div class=\"bigbox\"><br><h3>Here are the questions you missed:</h3><br>";
			echo "<br><br>";
$orgid2 = $orgid;
			echo "<br><br>";
asort ($orgid2);
var_dump ($orgid2);
			echo "<br><br>";
$orgid2 = join (',', $orgid2);
$orgid2 = rtrim ($orgid2, ',');
$newid = array();
foreach ($orgid as $key => $value)  {
	$newid[$value] = $key+1;
}

	$query = "SELECT * FROM entrytest WHERE id IN ($orgid2) ORDER BY id";
$result = mysql_query($query);
$i=1;	
		$k2 = key($orgid);

 while ($row = mysql_fetch_array($result)) {
 		$k = key($row);
		$x = $row['id'];
		$qno = $newid[$x];
		$i++;
		echo "<span class=\"b\">Question #" . $qno ." </span>was: \"" . $row[1] ."\".  <br>You answered \"" . $_POST['user_answer'][$qno-1] . "\", ";
	switch ($_POST['user_answer'][$qno-1]) {
case "a":
   echo "$row[2]";
   break;
case 'b':
   echo "$row[3]";
   break;
case 'c':
   echo "$row[4]";
   break;

}

echo ", but the correct answer was \"" . $row[5] . "\", \"" . $row[7] . "\".<br>";
			echo "<p>$row[6]</p>";
?>
			<img src="./../images/thinkingcapwhoa_color.png" class="c" width="90" height="108" alt=""><br><br>
<?php
	} // while
} // original if

?>
		</div>
	</div>

[darylr]

Hi masonbarge,

I have it working now! I cannot thank you enough 😃

Thank you! 🙂

[masonbarge]

mistake here:

$ans1[$i] = $row[3];
$ans2[$i] = $row[4];
$ans3[$i] = $row[5];

must be

$ans1[$i] = $row[2];
$ans2[$i] = $row[3];
$ans3[$i] = $row[4];

[darylr]

Yep, dont worry I caught that one out! 🙂

Ive a new problem now though. Ive created it so an ID is assigned for the test, so it can only be used once.

However, when I submit the test, if I fail, I can still hit BACK on my browser and continuosly change the answers until they turn to a pass. How can I prevent this?

[masonbarge]

I've never seen the code for one of these, Daryl. Understand, I'm just a more advanced noob.

If it's a serious test, I imagine you could require a real name and could submit the score to a database on click. One of my self-imposed disciplines in this test, however, was to use a "SELECT only" database connection, to maximize server security. There are a lot easier ways to do a quiz than putting the form handler in an "if" clause like this. Just put the handler on a different page.

My first thought would be to have a test introduction page that sets a session. Clicking to the result page would amend the session and disable another test result. In other words, you could start the test with an if clause "if session value = xxx" and if the session value is "xxx" (or alternately, if session value isn't "yyyy"), use a header to redirect to a page that says "sorry, if you want to take the test again, you have to start on the first page". This could redirect to the introduction page after five seconds.

That sounds pretty easy. You can't really stop the back button on the browser, but you can stop a resubmit.

Ultimately, there really isn't any way to prevent test cheating on the internet that doesn't involve tracking a real-world identity, though.

[darylr]

I sorted the problem by inserting a record whenever the form is submitted. It records the person's email address and ID of the test, so that if they hit back and try resubmit, it checks if their email and ID is the database - if it is, then it cancels everything and says "Sorry, this test has been submitted already" using a simple IF/ELSE clause 😃

Anyway, the system is working completely now 😃 Thanks for all your help! 🙂