It always says Correct! What did I do wrong? - php

Question

$number1 = mt_rand(1,9);
$number2 = mt_rand(1,9);
$total = $number1 * $number2;
echo "<form method='post'>";
echo $number1 . " x " . $number2 . " = <input type='number' name='num1' required /><br>";
echo "<input type='submit' value='submit!' name='done'>";
echo "</form>";
if (isset($_POST['done'])) {
if (isset($_POST['num1']) == $total) {
echo "Correct!";
} else {
echo "Wrong!";
}
}
It always says Correct! And I dont know why ( im a beginner ), I just want to check if num1 is equal to $total

Answer 1

You have many problems in your code :
you must first check if the post is submit then if its wrong type the form
if (isset($_POST['done'])) {
//your code
}
else {
//your form
}
save $total in session to reuse it when the form submit, in your case $total have different value every time
isset() return true or false you can't comparison true or false with integer value if you want to use isset your code must be like this:
if(isset($_POST['num1']) && $_POST['num1'] == $total) {
}

Answer 2

You're comparing isset($var) to $total. They're both truthy so the condition is always true as long as 'num1' is defined in your POST data.
Maybe you should do something like :
isset($_POST['num1']) && $_POST['num1'] == $total
You should also probably cast 'num1' to a number

Answer 3

As said by Tom Udding, every time you refresh the page it calls ALL of that code again, so number1 and number2 are being randomly selected again.
Your current code has no way of saving the previous variable values. An unconventional way would be to add a hidden form field with the answer to the question, like below:
<?php
if (isset($_POST['done']) && isset($_POST['num1']))
{
//Get answer from form.
$total = $_POST['answer'];
if ($_POST['num1'] == $total)
{
echo "Correct!";
}
else
{
echo "Wrong!";
}
}
$number1 = mt_rand(1, 9);
$number2 = mt_rand(1, 9);
$total = $number1 * $number2;
echo "<form method='post'>";
echo $number1 . " x " . $number2 . " = <input type='number' name='num1' required /><br>";
//Added hidden form with answer.
echo "<input type='number' hidden name='answer' value='$total' />";
echo "<input type='submit' value='submit!' name='done'>";
echo "</form>";
?>
HOWEVER...
In a realistic rich web application, you wouldn't put your answer in your form for users to see, this is where you can use sessions to track your user's information as they traverse (or in your case refresh) your page.
So a more practical answer to your question would be the following:
<?php
session_start();
if (isset($_POST['done']) && isset($_POST['num1']))
{
$answer = $_SESSION['answer'];
if ($_POST['num1'] == $answer)
{
echo "Correct!";
} else
{
echo "Wrong!";
}
}
$number1 = mt_rand(1, 9);
$number2 = mt_rand(1, 9);
$total = $number1 * $number2;
$_SESSION['answer'] = $total;
echo "<form method='post'>";
echo $number1 . " x " . $number2 . " = <input type='number' name='num1' required /><br>";
echo "<input type='number' hidden name='answer' value='$total' />";
echo "<input type='submit' value='submit!' name='done'>";
echo "</form>";
?>