Passing a value in the URL value not showing on the receiving php page

this is the code used to get the information from the database, the images I have taken off the echo statement for the time being, and just the name of the product. When I click on the product name it sends me to cart.php and should pass the value in the URL it shows in the browser when I hover over the text but when i click it send me to cart.php and just shows a blank page

$product_types = get_all_subjects2();

while($products = mysql_fetch_array($product_types))
{
    $name = $products['name'];
    $address = $products['image_location'];
    $description = $produ开发者_StackOverflow社区cts['description'];
    //echo $name;

    echo '<ul>';
    echo "<li><a href=\"http://localhost/project/cart.php?subj="  . urlencode($products["name"]) . 
        "\">{$products["name"]}</a></li>";  

the code used to see if value isset

<?php
if (isset($_POST['subj']))
{

    $a = $_POST['subj'];
    echo $a;
}

 else {
            echo"error";
         }
?>

---

The parameters passed via URL are in $_GET and not in $_POST:

$_GET

An associative array of variables passed to the current script via the URL parameters.

$_POST is only for parameters passed by HTTP POST method.

So try $_GET['subj'] instead.

---

You're checking the PHP $_POST but are sending the data through URL.

If you're sending information through the URL you need to get at it through $_GET

<?php
if (isset($_GET['subj'])) {
    $a = $_GET['subj'];
    echo $a;
} else {
     echo"error";
}         
?>