Creating the Quiz Machine Program

Getting the File List

Since most of the code in the QuizBuilder program works with a list of files, the getFiles() function is charged with that important task.

function getFiles(){
  //get list of all files for use in other routines

  global $dirPtr, $theFiles;

  chdir(".");
  $dirPtr = openDir(".");
  $currentFile = readDir($dirPtr);
  while ($currentFile !== false){
    $theFiles[] = $currentFile;
    $currentFile = readDir($dirPtr);
  } // end while

} // end getFiles

The first thing this function does is to change the file system so it is pointing at the current directory, and set up a pointer variable to that directory.

I then created an array called theFiles, which holds the name of every file in the directory. The theFiles variable is global, so it will be shared with the program and other functions that declare a reference to it.

Showing the "Take a Test" List

Most of your users will not be creating or editing quizzes. Instead, they will be taking them. In order to take a test, the user must choose a test and have the password associated with that test. To simplify choosing a test, the showTest() function grabs all the HTML files in the quiz directory and places them in a select list. The password goes in an ordinary password field. The code in showTest() creates a form that calls the takeQuiz.php program when it is submitted.

function showTest(){
  //print a list of tests for user to take

  global $theFiles;
  print <<<HERE
<form action = "takeQuiz.php"
      method = "post">

<table border = 1
       width = 400>
<tr>
  <td colspan = 2><center>
    <h3>Take a quiz</h3>
  </td>
</tr>

<tr>
  <td>Quiz Password</td>
  <td>
    <input type = "password"
           name = "password">
  </td>
</tr>

<tr>
  <td>Quiz</td>
  <td>
    <select name = "takeFile">

HERE;

  //select only quiz html files
  $testFiles = preg_grep("/html$/", $theFiles);

  foreach ($testFiles as $myFile){
    $fileBase = substr($myFile, 0, strlen($myFile) - 5);
    print "    <option value = $fileBase>$fileBase</option>\n";
  } // end foreach

  print <<<HERE
    </select>
  </td>
</tr>

<tr>
  <td colspan = 2><center>
    <input type = "submit"
           value = "go">
  </center></td>
</tr>
</table>

</form>

HERE;

} // end showTest

Although the code is long, almost all of it is pure HTML. The only part that's really PHP code is the part that selects HTML files and places them in the select group.

This code fragment uses the preg_grep() to select filenames ending in "HTML" and creates an option tag for that file. Note that I stripped out the .html part of the filename, because I won't really need it, and it would complicate some of the code coming up in the takeQuiz program.

Showing the Edit List

The showEdit() function works a lot like showTest(). This function is used to display a list of the master files on the system. Although it will often be exactly the same as the list of tests, it won't always be the same, because there can be master files that haven't yet been made into HTML files.

function showEdit(){
  // let user select a master file to edit

  global $theFiles;
  //get only quiz master files
  $testFiles = preg_grep("/mas$/", $theFiles);

  //edit a quiz
  print <<<HERE
<form action = "editQuiz.php"
      method = "post">
<table border = 1
       width = 400>
<tr>
  <td colspan = 2><center>
    <h3>Edit a quiz</h3>
  </center></td>
</tr>

<tr>
  <td>Administrative Password</td>
  <td>
    <input type = "password"
           name = "password"
           value = "">
  </td>
</tr>

<tr>
  <td>Quiz</td>
  <td>
    <select name = "editFile">
      <option value = "new">new quiz</option>

HERE;
  foreach ($testFiles as $myFile){
    $fileBase = substr($myFile, 0, strlen($myFile) - 4);
    print " <option value = $myFile>$fileBase</option>\n";
  } // end foreach

  print <<<HERE
    </select>
  </td>
</tr>

<tr>
  <td colspan = 2><center>
    <input type = "submit"
           value = "go">
  </center></td>
</tr>
</table>
</form>

HERE;

} // end showEdit

The showEdit() function is just like showQuiz() but the form points to the editQuiz.php program, and the file list is based on those files ending in "mas."

There's one other subtle but important difference. Look at the code for the select element and you'll see I added a "new quiz" option. If the user chooses this option, the editQuiz() function won't try to load a quiz file into memory, but will set up for a new quiz instead.

Showing the Log List

The last segment is meant for the quiz administrator. It allows the user with admin access to view the log of any quiz on the system. This will show who has taken the test, where and when they took it, and the score. When the user clicks on the Submit button associated with this part of the page, the showLog.php program will take over.

function showLog(){

  //let user choose from a list of log files
  global $theFiles;

  print <<<HERE

<form action = "showLog.php"
      method = "post">
<table border = 1
       width = 400>
<tr>
  <td colspan = 2><center>
    <h3>Show a log file</h3>
  </td>
</tr>

<tr>
  <td>Administrative Password</td>
  <td>
    <input type = "password"
           name = "password"
           value = "">
  </td>
</tr>

<tr>
  <td>Quiz</td>
  <td>
    <select name = "logFile">

HERE;

  //select only log files
  $logFiles = preg_grep("/log$/", $theFiles);
  foreach ($logFiles as $myFile){
    $fileBase = substr($myFile, 0, strlen($myFile) - 4);
    print "      <option value = $myFile>$fileBase</option>\n";
  } // end foreach

  print <<<HERE
    </select>
  </td>
</tr>

<tr>
  <td colspan = 2><center>
    <input type = "submit"
           value = "go">
  </td>
</tr>
</table>
</form>

HERE;
} // end showLog

?>

</center>
</body>
</html>

I decided that all log files would end with .log, so the program can easily get a list of log files to place in the select group.

Getting Existing Test Data

The first chore is to determine which quiz the user is requesting. Remember that the value "new" indicates that the user wants to build a new test, so that value is treated specially. Any other value will be the foundation of a test filename, so I open the appropriate master file and load its values into the appropriate elements on the form.

<html>
<head>
<title>Quiz Builder</title>
</head>
<body>
<?

if ($password != "absolute"){
  print <<<HERE

<font color = "red" size = +3>
Invalid Password!
</font>

HERE;
} else {
  //check to see if user has chosen a form to edit
  if ($editFile == "new"){
    //if it's a new file, put in some dummy values
    $quizName = "sample test";
    $quizEmail = "root@localhost";
    $quizData = "q:a:b:c:d:correct";
    $quizPwd = "php";
  } else {
    //open up the file and get the data from it
    $fp = fopen($editFile, "r");
    $quizName = fgets($fp);
    $quizEmail = fgets($fp);
    $quizPwd = fgets($fp);
    while (!feof($fp)){
      $quizData .= fgets($fp);
    } // end while
    fclose($fp);
} // end 'new form' if

I decided to code the value "absolute" (from the name of this book series) as an administrative password. Each test will have its own password, and the administrative functions (like editing a quiz) have their own password. If the password field has any other value besides my chosen password, the program will indicate a problem and refuse to move forward.

Once you know the user is authorized to edit tests, you need to determine if it's a new test or an existing quiz. If the quiz is new, I simply add some sample data to variables, which will be used for the upcoming form. If the user wants to see an existing test, I open the file for read access, and grab the first three lines, which will correspond to the $quizName, $quizEmail, and $quizPwd fields.

I then use a foreach loop to load up the rest of the file into the $quizData variable.

Printing Out the Form

Once the variables are loaded with appropriate values, it's a simple matter to print up an HTML form to let the user edit the quiz. The form is almost all pure HTML with the quiz variables interpolated into the appropriate places.

print <<<HERE

<form action = "writeQuiz.php"
      method = "post">

<table border = 1>
<tr>
  <th>Quiz Name</th>
  <td>
    <input type = "text"
           name = "quizName"
           value = "$quizName">
  </td>
</tr>

<tr>
  <th>Instructor email</th>
  <td>
    <input type = "text"
           name = "quizEmail"
           value = "$quizEmail">
  </td>
</tr>

<tr>
  <th>Password</th>
  <td>
    <input type = "text"
           name = "quizPwd"
           value = "$quizPwd">

<tr>
  <td rowspan = 1
      colspan = 2>
    <textarea name = "quizData"
              rows = 20
              cols = 60>
$quizData</textarea>
  </td>
</tr>

<tr>
  <td colspan = 2><center>
    <input type = "submit"
           value = "make the quiz">
  </center></td>
</tr>

</table>
</form>
HERE;
} // end if

?>
</body>
</html>

Setting up the Main Logic

The first job is to create two files. The quiz name can be the foundation of the filename, but many file systems choke at spaces within filenames, so I use the str_replace() function to replace all spaces in $quizName to underscore characters (_). Then I create a filename for the master file ending in .mas and another filename for the actual quiz ending in .html. To create the HTML file, I open it up for write output. Then I use the buildHTML() function (which will be described shortly) to build the HTML code, and I write that code out to the html file and close the file.

The master file is built in pretty much the same way, except it calls the buildMas() function in order to create the appropriate text for the file.

<html>
<head>
<title>Write Quiz</title>
</head>
<body>
<?
//given a quiz file from editQuiz,
//generates a master file and an HTML file for the quiz

//open the output file
$fileBase = str_replace(" ", "_", $quizName);
$htmlFile = $fileBase . ".html";
$masFile = $fileBase . ".mas";

$htfp = fopen($htmlFile, "w");
$htData = buildHTML();
fputs($htfp, $htData);
fclose($htfp);

$msfp = fopen($masFile, "w");
$msData = buildMas();
fputs($msfp, $msData);
fclose($msfp);

//preview the actual master file
print <<<HERE
<pre>
$msData
</pre>

HERE;

To make sure things were going well, I added a check to the end of the page that prints out the actual contents of the master file. The output of this program lets the administrator check to see that the test is working correctly. The administrator can actually take the test and submit it to the grading program from this page. If there is a problem with the test, it's convenient to have the actual contents of the .mas file visible on the page. Of course, the final HTML page will not contain this data, because it holds the answers.

Building the Master File

The master file routine is very straightforward.

function buildMas(){
  //builds the master file
  global $quizName, $quizEmail, $quizPwd, $quizData;
  $msData = $quizName . "\n";
  $msData .= $quizEmail . "\n";
  $msData .= $quizPwd . "\n";
  $msData .= $quizData;
  return $msData;
} // end buildMas

The critical part of this file is remembering the file structure rules, so any program that reads this file doesn't get confused. The quiz name should go on the first line, followed by a newline character. The $quizEmail and $quizPwd variables follow on their own lines, and finally all the $quizData (which will usually be several lines) should go to the end of the file. Note that the function doesn't actually store the data to the file, but returns it to the main program. This allows a little more flexibility, so I can write the data to both the file and the page.

Building The HTML File

The function that creates the HTML is a little more involved, but it still isn't too hard. The basic strategy is this: Build an HTML form containing all the questions. For each line of the master file, build a radio group. Place the question and all the possible answers in a set of nested <ol> elements. At the end of the page, there should be one Submit button. When the user clicks on the Submit button, the system will call the gradeQuiz.php page, which will evaluate the user's responses.

function buildHTML(){
  global $quizName, $quizData;
  $htData = <<<HERE
<html>
<head>
<title>$quizName</title>
</head>
<body>

HERE;

  //get the quiz data
  $problems = split("\n", $quizData);
  $htData .= <<<HERE
<center>
<h1>$quizName</h1>
</center>

<form action = "gradeQuiz.php"
      method = "post">

Name
<input type = "text"
       name = "student">

<ol>

HERE;
  $questionNumber = 1;

  foreach ($problems as $currentProblem){
      list($question, $answerA, $answerB, $answerC, $answerD, $correct) =
      split (":", $currentProblem);
      $htData .= <<<HERE
<li>
  $question
  <ol type = "A">
    <li>
      <input type = "radio"
             name = "quest[$questionNumber]"
             value = "A">
      $answerA
    </li>

    <li>
      <input type = "radio"
             name = "quest[$questionNumber]"
             value = "B">
      $answerB
    </li>

    <li>
      <input type = "radio"
             name = "quest[$questionNumber]"
             value = "C">
      $answerC
    </li>

    <li>
      <input type = "radio"
             name = "quest[$questionNumber]"
             value = "D">
      $answerD
    </li>

  </ol>

</li>

HERE;
    $questionNumber++;

  } // end foreach
  $htData .= <<<HERE
</ol>

<input type = "hidden"
       name = "quizName"
       value = "$quizName">

<input type = "submit"
       value = "submit quiz">

</form>

HERE;

  print $htData;
  return $htData;
} // end buildHTML

?>
</body>
</html>

Most of the critical information this function needs is stored in $quizData. Each line of $quizData stores one question, so I use a split() function to break $quizData into an array called $problems. I use a foreach loop to step through each problem. Each problem contains a list of values, which is separated into a series of scalar variables with the combination of split() and list().

Within the foreach loop, I also added the HTML code necessary to print out the current question's information. Take a careful look at the code for the radio buttons. Recall that radio buttons that will operate as a group should all have the same name. I did this by calling them all quest[$questionNumber]. The $questionNumber variable will contain the current question number, and this value will be interpolated before the HTML code is written. Question number 1 will have four different radio buttons called quest[1]. The gradeQuiz program will see this as an array called $quest.

At the end of the HTML, I added the quiz name as a hidden field, and the Submit button.

Opening the Files

The gradeQuiz program, like all the programs in this system, relies on files to do all its important work. In this case, the program will use the master file to get the answer key for the quiz, and will write to a log file.

<?
print <<<HERE
<html>
<head>
<title>Grade for $quizName, $student</title>
</head>
<body>

</body>
<h1>Grade for $quizName, $student</h1>
HERE;

//open up the correct master file for reading
$fileBase = str_replace(" ", "_", $quizName);
$masFile = $fileBase . ".mas";
$msfp = fopen($masFile, "r");

$logFile = $fileBase . ".log";

//the first three lines are name, instructor's email, and password
$quizName = fgets($msfp);
$quizEmail = fgets($msfp);
$quizPwd = fgets($msfp);

The master file is opened with read access. The first three lines are unimportant, but I must still read them in to get to the quiz data.

Creating an Answer Key

I start by generating an answer key from the master file. I'll step through each question in the file, and extract all the normal variables from it (although all I'm really interested in is the $correct variable). I then store the value of $correct into an array called $key. At the end of this loop, the $key array will hold the correct answer for each question in the quiz.

//step through the questions building an answer key
$numCorrect = 0;
$questionNumber = 1;
while (!feof($msfp)){
  $currentProblem = fgets($msfp);

  list($question, $answerA, $answerB, $answerC, $answerD, $correct) =
  split (":", $currentProblem);
  $key[$questionNumber] = $correct;
  $questionNumber++;
} // end while
fclose($msfp);

Checking the User's Response

The user's responses will come from the HTML form as an array called $quest. The correct answers are in an array called $key. To grade the test, I can simply step through both arrays at the same time, comparing the user's response with the correct response. Each time these values are the same, the user has gotten an answer correct. When the values are not the same, the user was incorrect (or there was a problem with the test itself-don't discount that as a possibility).

//Check each answer from user
for ($questionNumber = 1; $questionNumber <= count($quest); $questionNumber++){
  $guess = $quest[$questionNumber];
  $correct = $key[$questionNumber];
  $correct = rtrim($correct);
  if ($guess == $correct){
    //user got it right
    $numCorrect++;
    print "problem # $questionNumber was correct<br>\n";
  } else {
    print "<font color = red>problem # $questionNumber was incorrect</font><br>\n";
  } // end if
} // end for

I chose to give a certain amount of feedback telling whether the question was correct or not, but I decided not to display the right answer. You might wish to give the user more or less information, depending on how you're using the quiz program.

Reporting the Results to Screen and Log File

After checking each answer, the program reports the results to the user as a raw score and a percentage. The program also opens up a log file for append access and adds the current data to it. Append access is just like write access, but rather than overwriting an existing file, it adds any new data to the end of it.

print "you got $numCorrect right<br>\n";
$percentage = ($numCorrect /count($quest)) * 100;
print "for $percentage percent<br>\n";

$today = date ("F j, Y, g:i a");
//print "Date: $today<br>\n";
$location = getenv("REMOTE_ADDR");
//print "Location: $location<br>\n";

//add results to log file
$lgfp = fopen($logFile, "a");
$logLine = $student . "\t";
$logLine .= $today . "\t";
$logLine .= $location . "\t";
$logLine .= $numCorrect . "\t";
$logLine .= $percentage . "\n";

fputs($lgfp, $logLine);
fclose($lgfp);

?>

</html>

I added a few more elements to the log file that might be useful to a test administrator. Of course, I added the student's name and the current date. You might want to look at the online help for the date() function to see all the various ways you can display the current date. I also added a location variable, which uses the $REMOTE_ADDR environment variable to indicate which machine the user was on when he or she submitted the exam. This can be useful information, because it can alert you to certain kinds of hacking. (A person taking the same quiz several times on the same machine but with a different name, for example.) The gradeQuiz program adds the number correct and the percentage to the log file as well, then closes the file. Notice that the data in the log file is delimited with tab characters. This is done so an analysis program could easily work with the file using the split command. Also, most spreadsheet programs can readily read a tab-delimited file, so the log file can be easily imported into a spreadsheet for further analysis.