Listing 2: The final version of edit-quizfile.pl.

#!/usr/bin/perl -w


use strict;
use diagnostics;
use CGI;        # Available from https://www.perl.com/CPAN
use QuizQuestions;


# Maximum number of questions in a quiz
my $MAX_QUESTIONS = 10;


# Default quizname
my $quizname = "";


# Create an instance of CGI
my $query = new CGI;


# Print the MIME header that we will always use
print $query->header("text/html");


# Determine how we were invoked
my $request_method = $query->request_method;


# ------------------------------------------------------------
# If we were invoked via POST, then save the changes


if ($request_method eq "POST")
{
    $quizname = $query->param("quizname");


    # Create an instance of QuizQuestions
    my $questions = new QuizQuestions($quizname);


    # Add questions to $questions
    my $counter = 0;


    foreach $counter (0 .. $MAX_QUESTIONS)
    {
   # Only handle as many questions as were filled in, by
   # checking to see if the question was entered
   last unless ($query->param("question-$counter") ne "$counter");


   # Set the question
   my @question = ($query->param("question-$counter"),
         $query->param("answer-a-$counter"),
         $query->param("answer-b-$counter"),
         $query->param("answer-c-$counter"),
         $query->param("answer-d-$counter"),
         $query->param("correct-$counter"));


   # Add the question to the quiz
   $questions->addQuestion(@question);
    }


    # Save the questions to disk
    my $result = $questions->saveFile;

    # If something went wrong, tell us what it was
    if ($result ne "0")
    {
   print $query->start_html(-title => "Error");
   print "$result</P>\n";
   print $query->end_html;
   exit;
    }
}


# ------------------------------------------------------------
# If we were invoked using GET, then get the name of
# the quizfile


if ($request_method eq "GET")
{
    # If the query string is empty, then produce a page of HTML
    # containing ISINDEX
    if ($query->param("keywords") eq "")
    {
   print $query->start_html(-title => "Enter a quiz name");
   print "Please enter the name of the quiz you want ";
   print "to create or edit in the below .</P>\n";
   print "<ISINDEX>\n";
   print $query->end_html;


   exit;
    }
    else
    {
   # Get the name of the quiz
   $quizname = $query->param("keywords");
    }
}


# Whether we were invoked with GET or POST, display
# the current state of the quiz


# Create a new instance of QuizQuestions
my $questions = new QuizQuestions($quizname);


# Read the questions from disk, ignoring errors
# (since we will happily create a new quiz)
my $result = $questions->loadFile;


# Create the header for the HTML page
print $query->start_html(-title => "Create/Edit a quiz");


# Define a form
my $script_name = $query->script_name;
print "<Form method="POST" action="$script_name">\n";


# Create the text element for the quiz name
print "Editing quiz:<input type="text" name="quizname" ";
print "value="$quizname"></P>\n";
print "<HR>\n\n";


# Now create one form element for each existing question


my $counter = 0;
foreach $counter (0 .. $MAX_QUESTIONS)
{
    # Get a particular question
    my ($qtext, $ansA, $ansB, $ansC, $ansD, $correct)
   = $questions->getQuestion($counter);


    # Question text
    print "<H2>Question $counter</H2>\n";
    print "Question text: <input type="text" ";
    print "name="question-$counter" value="$qtext" ";
    print "size="30"></P>\n";


    # Answer A
    print "Answer A: <input type="text" value="$ansA" ";
    print "name="answer-a-$counter" size="30"></P>\n";


    # Answer B
    print "Answer B: <input type="text" value="$ansB" ";
    print "name="answer-b-$counter" size="30"></P>\n";


    # Answer C
    print "Answer C: <input type="text" value="$ansC" ";
    print "name="answer-c-$counter" size="30"></P>\n";


    # Answer D
    print "Answer D: <input type="text" value="$ansD" ";
    print "name="answer-d-$counter" size="30"></P>\n";


    # Correct answer
    print "Correct answer: <select name="correct-$counter">\n";

    my $letter = "";
    foreach $letter ("a","b","c","d")
    {
   print "<option ";
   print "selected " if ($letter eq $correct);
   print "$letter>$letter\n";
    }


    print "</select>\n";
    print "<HR>\n\n";
}


# Now that the loop is complete, we can finish things up
print '', "\n";
print "\n";
print $query->end_html;