Passing a PHP Value from a link - php

Question

I am new to PHP and learning. I'm trying to pass a value through a url link but it doesn't seem to work.
The link value I am passing is http://www.mysite.com/index.php?id=f
I want to run a js script if ID not F seen below but right now when I run it. It doesn't do anything:
<?php
$ShowDeskTop = $_GET['id'];
if (isset($ShowDeskTop)){
echo $ShowDeskTop;
if ($ShowDeskTop != "f"){
echo "ShowDeskTop Value is not F";
echo "<script type=\"text/javascript\">";
echo "if (screen.width<800)";
echo "{";
echo "window.location=\"../mobile/index.php\"";
echo "}";
echo "</script>";
};
};
?>
I know this is easy PHP 101 but I can't figure it out. I have tried everything from w3schools to other sites on Google for the answer and having no luck. Could someone please tell me what I am doing wrong?
Thank you!

Answer 1

$ShowDeskTop is not the same as $ShowDesktop variables names are case sensitive!

Answer 2

This is never gonna work since you set the variable AFTER checking if it exist..
The most easy way:
<?php
if (isset($_GET['id'])) {
echo $_GET['id'];
if ($_GET['id'] != 'f') {
?>
<script type="text/javascript">
if (screen.width < 800) {
window.location = "../mobile/index.php";
}
</script>
<?php
}
}
?>
I don't think <> is valid in PHP (it is in VB.NET ..) the is not operator is != or !== (strict/loose comparison).
Also you don't have to close if statements with a ;
This:
if (expr) {
}
Is valid and not this:
if (expr) {
};

Answer 3

I thought about writing != instead of <>.

Answer 4

You have a number of problems including bad variable case (i.e. variables not matching), checking for variables before they exist, etc. You can simply do something like this:
if (!empty($_GET['id'])) { // note I check for $_GET['id'] value here not $ShowDeskTop
$ShowDeskTop = $_GET['id'];
echo $ShowDeskTop; // note I change case here
if ($ShowDeskTop !== "f"){ // note the use of strict comparison operator here
echo "YES, the id doesn't = f";
echo "<script type=\"text/javascript\">";
echo "if (screen.width<800)";
echo "{";
echo "window.location=\"../mobile/index.php\"";
echo "}";
echo "</script>";
} // note the removal of semicolon here it is not needed and is bad coding practice in PHP - this is basically just an empty line of code
} // removed semicolon here as well

Answer 5

Fist thing, you need ; at the end of echo $ShowDesktop
And, what does f mean in if ($ShowDeskTop <> "f"){

Answer 6

use strcmp() instead of <> operator.
Try
if(!strcmp($ShowDeskTop, "f")){
echo "YES, the id doesn't = f";
}

Answer 7

<?php
$ShowDeskTop = $_GET['id']; // assign before checking
if (isset($ShowDeskTop)){
//echo $ShowDeskTop;
if ($ShowDeskTop !== "f"){
echo "YES, the id doesn't = f";
echo "<script type='text/javascript'>";
echo "if (screen.width<800)";
echo "{";
echo "window.location.replace('../mobile/index.php');"; // assuming your path is correct
echo "}";
echo "</script>";
}
}
?>