How much is 2 + 2?

Question

I'm currently working on a kind of PHP Quiz about mathematical calculations. We show a mathematical equation, and user need to input his answer.

Currently, this is what I have written:

echo '<div class="table-title">Super Quizz</div>';

echo '<div class="row text-center quizz">';

function addition($x, $y) { return $x + $y; }
function substraction($x, $y) { return $x - $y; }
function multiplication($x, $y) { return $x * $y; }
function division($x, $y) { return $x / $y; }

do {
    $firstNumber = rand(1, 10);
    $secondNumber = rand(1, 10);

    $operatorsCharacteres = array('+', '-', 'x', '/');
    $operatorsLetter = array('addition', 'substraction', 'multiplication',             'division');
    $operande = array_rand($operatorsLetter);
    $result = call_user_func_array($operatorsLetter[$operande],     array($firstNumber, $secondNumber));
}while($result < 0);


echo $firstNumber.' '.$operatorsCharacteres[$operande].' '.$secondNumber.' = <input type="text" name="answer" maxlength="3" class="input-quizz" >';
echo '<input type="hidden" value="'.$result.'">';

echo ' </div>';

echo '<div class="table-title"><a href="#" type="submit">I valid !</a></div>';
echo 'Result : '.$result;

If something is wrong, or not optimised, please, tell me, and teach me.

Answer 1

Naming

The naming of the arrays related to the operators is not so great:

• In $operatorsLetter you have the names of functions that do some operation. $operatorFunctionNames or even $operatorFunctions would be a better name.
• In $operatorsCharacteres you have the symbols of operations. These are normally not called characters. So $operatorSymbols would be a better name.
• In $operande you have the key of a random operator. That's not an operand. In the operation 3 + 9, the operands are 3 and 9, but in your code it's "addition". So $operatorIndex would be a better name.

With these renames, the code is slightly easier to understand:

$operatorSymbols = array('+', '-', 'x', '/');
$operatorFunctions = array('addition', 'substraction', 'multiplication', 'division');
$operatorIndex = array_rand($operatorFunctions);
$operatorSymbol = $operatorSymbols[$operatorIndex];
$operatorFunction = $operatorFunctions[$operatorIndex];
$result = call_user_func_array($operatorFunction, array($firstNumber, $secondNumber));

I also introduced the helper variables $operatorSymbol and $operatorFunction, to shorten the lines later in the code that use them.

Printing in PHP

An easier way to print in PHP is to simply move text outside of <?php ... ?> blocks. For example these lines at the beginning of your script are a bit tedious to write using echo statements:

echo '<div class="table-title">Super Quizz</div>';

echo '<div class="row text-center quizz">';

Instead, you could change your script to put the beginning <?php after those lines, like this:

<div class="table-title">Super Quizz</div>
<div class="row text-center quizz">

<?php
function addition($x, $y) { return $x + $y; }
function substraction($x, $y) { return $x - $y; }
// ...

I would do similarly near the end of the file too, like this:

// ...
echo $firstNumber.' '.$operatorSymbol.' '.$secondNumber;
?>
 = <input type="text" name="answer" maxlength="3" class="input-quizz" >
    <input type="hidden" value="<?php echo $result ?>">

</div>

<div class="table-title"><a href="#" type="submit">I valid !</a></div>
Result : <?php echo $result ?>

Answer 2

I would:

• improve (avoid) the PHP & HTML mixing.
• use one associative array instead of two array in order to define the operators
• avoid a while. If the problem is the substraction, then check if the result is < 0 and switch the variable. Because in your case the substraction case will be less probable than other operators.
• call_user_func_array could be simply replaced legitimately by a variable ($funcName())

code

<?php
function addition($x, $y) { return $x + $y; }
function substraction($x, $y) { return $x - $y; }
function multiplication($x, $y) { return $x * $y; }
function division($x, $y) { return $x / $y; }

$firstNumber  = mt_rand(1, 10);
$secondNumber = mt_rand(1, 10);

$operators = array(
    'addition'       =>'+', 
    'substraction'   =>'-', 
    'multiplication' =>'x', 
    'division'       =>'/'
);

$operator = array_rand($operators);

$result = $operator($firstNumber, $secondNumber);

if($result < 0) {
    list($firstNumber,$secondNumber) = array($secondNumber, $firstNumber);
    $result *= -1;
}

?>
<div class="table-title">Super Quizz</div>
<div class="row text-center quizz">
    <?=$firstNumber?> <?=$operators[$operator]?> <?=$secondNumber?> = <input type="text" name="answer" maxlength="3" class="input-quizz" >
    <input type="hidden" value="<?=$result?>">
</div>
<div class="table-title"><a href="#" type="submit">I valid !</a></div>
Result : <?=$result?>

Just a note about <?=. This syntax could be disabled by .ini configuration if your PHP is <=5.3. In this case you must use the most verbose <?php echo

Another thing about rand. I've replaced automatically in my mind rand with mt_rand because this last "Generate a better random value". It's not so important in this context but it's a good thing start to use it for all.