Appending string with variable in PHP and looping

Question

I am calling some variables from MySQL database and comparing them with some variables which are being POSTED via a HTML form from a previous page. They are actually correct answers and given answers.

My current structure looks like this:

if($ans1==$que1){
echo"TRUE";
}
if($ans2==$que2){
echo"TRUE";
}
if($ans3==$que3){
echo"TRUE";
}
//AND SO ON...

The structure was not really hectic until there were only 3 questions. But now the questions are increased to 100. I want to know how to do something like this:

for(i=1; i=100; i++){
if($ans.$i==$que.$i){
echo"TRUE";
$total_correct_ans=$total_correct_ans+1;
}
}
echo"Total correct answers are ". $total_correct_ans;

why not do a foreach() loop through the post array

user557846
– user557846

2013-07-11 00:20:40 +00:00
Commented Jul 11, 2013 at 0:20 — user557846
– user557846, Commented Jul 11, 2013 at 0:20

Ja͢ck · Accepted Answer · 2013-07-11 00:21:29Z

3

First off, consider using arrays instead; they're meant for this kind of repetitive stuff:

// $answers = [1, 3, 2];
// $questions = [1, 2, 3];
for ($i = 0; $i < count($answers); ++$i) {
    if ($answers[$i] == $questions[$i]) { 
        echo "TRUE" 
    };
}

If that's really not possible, you could use variable variables:

if (${"ans$i"} == ${"que$i"}) {
}

answered Jul 11, 2013 at 0:21

Ja͢ck

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Comments

Atli · Accepted Answer · 2013-07-11 00:42:10Z

You could also use more complex arrays to both set up the question form and to then check for the answers. Consider if you had this array:

$questions = array(
    array(
        "question" => "What color is the sky",
        "answers" => array(
            "red",
            "green",
            "blue",
            "penquine"
        ),
        "correct_answer" => 2
    ),
    array(
        "question" => "What is the bestest langugage in the world!",
        "answers" => array(
            "C#",
            "English",
            "Brainfuck",
            "PHP",
        ),
        "correct_answer" => 3
    ),
);

In the page where the questions are asked, you could create the form by going through the array and printing each question with it's answers. Somewhat like:

echo "<form action='check_answers.php' method='post'>\n";
foreach ($questions as $qi => $q) {
    echo "<h1>{$q["question"]}</h1>\n";
    foreach ($q["answers"] as $ai => $answer) {
        echo "<label><input type='radio' name='answers[$qi]' value='$ai'> $answer</label>\n";
    }
}
echo "<input type='submit'></form>";

The data could then be checked in the check_answers.php file by comparing the "correct_answers" element in each question with the value provided by the form.

if (isset($_POST["answers"]) && is_array($_POST["answers"])) {
    $correctAnswers = array();
    $incorrectAnswers = array();

    foreach ($_POST["answers"] as $question => $answer) {
        if ($questions[$question]["correct_answer"] == $answer) {
            $correctAnswers[] = $questions;
        }
        else {
            $incorrectAnswers[] = $question;
        }
    }

    echo "You had " . count($correctAnswers) . " correct answers.<br>\n";
    echo "You had " . count($incorrectAnswers) . " incorrect answers.<br>\n";
}

You could even extend that to show precicely which questions the user got wrong and which right, as the indexes for both are stored in the arrays.

The $questions array, although being static in the above example, could also easily be generated from a MySQL schema.

function generateQuestions(\PDO $pdo) {
    $questions = array();

    $sql = "SELECT id, question FROM questions";
    $result = $pdo->query($sql);
    foreach ($result as $row) {
        $question = array(
            "question" => $row["question"],
            "answers" => array(),
            "correct_answer" => 0
        );

        $answerSql = "SELECT id, answer, isCorrect FROM answers
                    WHERE question_id = {$row["id"]}";
        $answerResult = $pdo->query($answerSql);
        foreach ($answerResult as $answer) {
            $answers[$answer["id"]] = $answer["answer"];
            if ($anser["isCorrect"]) {
                $question["correct_answer"] = $answer["id"];
            }
        }

        $questions[$row["id"]] = $question;
    }

    return $question;
}

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