PHP Q: Variables in <?php ?> not accessible in if/else - php

Question

So, I'm building a simple program that requires the user input a number which is then posted and generated into several random similar numbers.
The program then requires the user choose the correct variable, which would then be validated by the program.
I'm having issues with what I think is a variable not being 'available' for lack of a better word in the if/else statement.
I feel like I'm making a really simple/stupid mistake.
<?php
$numb = $_GET["number"];
switch ($numb) {
case 1:
echo "1x<br>";
$ans = 1; $n1 = rand(($ans - 5), ($ans + 5)); $n2 = rand(($ans - 5), ($ans + 5)); $n3 = 1; $n4 = rand(($ans - 5), ($ans + 5));
break;
case 2:
echo "2";
break;
case 3:
echo "3";
break;
} echo $ans;
if(isset($_POST['submit']))
{
$rb = $_POST['radio'];
if($rb == $ans){echo "test";}
else{echo "fail";}
}
?>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="POST">
<input type="radio" name="radio" value="<?php echo $n1; ?>"><?php echo $n1 ?>
<input type="radio" name="radio" value="<?php echo $n2; ?>"><?php echo $n2 ?>
<input type="radio" name="radio" value="<?php echo $n3; ?>"><?php echo $n3 ?>
<input type="radio" name="radio" value="<?php echo $n4; ?>"><?php echo $n4 ?>
<input type="submit" name="submit" value="submit" />
</form>

Answer 1

You have to define the variables before useing them in the switch/case.
// Check if get is used
if (isset($_GET['number'])){
$numb = $_GET["number"];
// predefine Variables here
$ans = '';
$n1 = '';
$n2 = '';
$n3 = '';
$n4 = '';
switch ($numb)
{
case 1:
echo "1x<br>";
$ans = 1;
$n1 = rand(($ans - 5), ($ans + 5));
$n2 = rand(($ans - 5), ($ans + 5));
$n3 = 1;
$n4 = rand(($ans - 5), ($ans + 5));
break;
case 2:
echo "2";
break;
case 3:
echo "3";
break;
}
echo $ans;
if (isset($_POST['submit']))
{
$rb = $_POST['radio'];
if ($rb == $ans)
{
echo "test";
}
else
{
echo "fail";
}
}
?>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="POST">
<input type="radio" name="radio" value="<?php echo $n1; ?>"><?php echo $n1 ?>
<input type="radio" name="radio" value="<?php echo $n2; ?>"><?php echo $n2 ?>
<input type="radio" name="radio" value="<?php echo $n3; ?>"><?php echo $n3 ?>
<input type="radio" name="radio" value="<?php echo $n4; ?>"><?php echo $n4 ?>
<input type="submit" name="submit" value="submit"/>
</form>
<?php
} else {
echo "Number not set in get!";
}

Answer 2

You have to use $global variable.
PHP Variables Manual
<?php
$numb = $_GET["number"];
$ans = 0;
switch ($numb) {
case 1:
echo "1x<br>";
$ans = 1;
$n1 = rand(($ans - 5), ($ans + 5));
$n2 = rand(($ans - 5), ($ans + 5));
$n3 = 1;
$n4 = rand(($ans - 5), ($ans + 5));
break;
case 2:
echo "2";
break;
case 3:
echo "3";
break;
} echo 'Answer : [' . $ans . ']<br>';
if(isset($_POST['submit']))
{
$rb = $_POST['radio'];
echo 'PostAnswer : [' . $ans . ']<br>';
if($rb == $ans)
{
echo "Good!";
}
else
{
echo "Bad!";
}
}
?>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>?number=1" method="POST">
<input type="radio" name="radio" value="<?php echo $n1 ?>"><?php echo $n1 ?>
<input type="radio" name="radio" value="<?php echo $n2 ?>"><?php echo $n2 ?>
<input type="radio" name="radio" value="<?php echo $n3 ?>"><?php echo $n3 ?>
<input type="radio" name="radio" value="<?php echo $n4 ?>"><?php echo $n4 ?>
<input type="submit" name="submit" value="submit" />
</form>
Your page will change after pressing submit button.
ex:) url_php = test.php request parameter : ?number=1
1) inputing /test.php?number=1
2) $ans = 1
3) After pressing submit button
4) $ans = ""
Like that! You have to maintain ?number=1 or fix it!