While statement repeats infinitely - php

Question

I have a website where i need to use a while statement, but when i use it, it repeats the echo infinitely. Although it looks like i could make it work without while, that isnt so, this is a simplified version of a final product that will need while.
<?php
$passlevel = '0';
while ($passlevel == '0')
{
if(isset($_GET['box_1_color']))
{
$color=$_GET['box_1_color'];
if($color == "#800080")
{
echo "you have passed step one.";
$passlevel == '1';
}
else
{
echo "you didn't select purple.";
}
}
else echo "contact webmaster";
}
?>
Why is it echoing either contact webmaster or you didnt select purple an infinite number of times?

Answer 1

First, you probably need to change:
$passlevel == '1';
to
$passlevel = '1';
The first is a comparison equals, not an assignment equals.
Second, if $color is not #800080, then the loop does not terminate and thus repeats forever as nothing in the loop causes the value to change.
I'm not entirely sure of the point of this loop in the first place. It should work perfectly fine without the loop, however you've stated that your code is a simplified version of something more complicated that indeed needs a loop. Perhaps you can elaborate.

Answer 2

You're not providing any way out of the loop. If $_GET['box_1_color'] isn't purple the first time through the loop, it can't possibly become anything else the second time through the loop, so it'll keep being the wrong color each and every time.
I'm not certain what you intended for this loop to accomplish. If you're trying to have the user enter a new value each time, you won't be able to do that with a loop in PHP. You'll have to regenerate the entire page (with an error message, presumably) and ask the visitor to submit the form again.

Answer 3

In the case of "contact webmaster", you need to break out of the loop, either with the break expression or by setting your $passlevel to anything other than zero. A more serious real problem is revealed in #Mike Christensen's answer, though

Answer 4

If $_GET['box_1_color'] is not set, the variable $passlevel will never be changed.

Answer 5

<?php
$passlevel = 0;
while ($passlevel == 0 || $passlevel == 2)
{
if(isset($_GET['box_1_color']))
{
$color=$_GET['box_1_color'];
if($color == "#800080")
{
echo "you have passed step one.";
$passlevel = 1;
}
else
{
echo "you didn't select purple.".'try again.';
}
}
else
{
echo "contact webmaster";
$passlevel = 2;
}
}
?>
You need to define another passlevel for failure, to stop the while loop. Also, don't put any quotes around integers.