input calculate number

Hi, i made a simple php code,

im not getting the incorrect answer,

<?

$num = "12";
$num2 = "3";

$cal = $num - $num2;

echo $cal ;

?>
<title><?php echo $cal?></title>
<form action="page.php" method="POST">
    what is <?php echo $num . " - " .$num2?> ? <input type="text" name="cap">
    <input type="submit" value="Submit">

</form>

PHP:

<?

$num = "12";
$num2 = "3";

$cal = $num - $num2;

$cap = $_POST['cap'];

if ($cal !== $cap){
    echo "yes 12 - 3 is ". $cap;
}else{
    "No, the answare is incorect";
}
?>

PHP:

 

If you are going to use strict variable comparisons (===. !===) the best way to test why the variables do not match is by using var_dump($var). Which will show you the variable type.

You either have to typecast the values or just use normal comparison:

<?php
$num = 12;
$num2 = 3;

$cal = $num - $num2;

$cap = (int) $_POST['cap'];

if ($cal !== $cap) {
    echo "yes 12 - 3 is ". $cap;
} else {
    "No, the answare is incorrect";
}

PHP:

Or:

$num = "12";
$num2 = "3";

$cal = $num - $num2;

$cap = $_POST['cap'];

if ($cal != $cap) {
    echo "yes 12 - 3 is ". $cap;
} else {
    "No, the answare is incorrect";
}

PHP:

 

im not good whit php
but
i meant, if you enter the wrong number its still saying that yes 12 - 3 is any number .

so in first/index page it says what is 12 - 3 ? if you enter the wrong/ any number its saying that yes 12 - 3 is displays any number you have entered.