Problem with locating image directory from root

[milkman_joe]

All i want to do is change my following method that works fine, so that it checks from the root directory.
This is what i originally have and works fine:

$file_name = 'products/'.$pId.'s.jpg';
if (file_exists($file_name))
$test = true;
else
$file_name = 'template/noimage.gif';

I tried changing the following line but it does not locate the image:
$file_name = '../products/'.$pId.'s.jpg';

The folder 'products' and 'template' are in the root directory.
ie. root/products

Could anyone help me with this problem?
Thanks in advance.

[R e b r a n d t]

$file_name = '/products/'.$pId.'s.jpg';

[milkman_joe]

I replaced the top line with:
$file_name = '/products/'.$pId.'s.jpg';

however it did not fix the problem.
Now it shows every image as 'template/noimage.gif'.

Even if the file exists in the products table, it is not finding it for some reason.

[dcrombie]

$file_name = "{$_SERVER['DOCUMENT_ROOT']}/products/{$pId}s.jpg";

;)

[milkman_joe]

Ok i replaced the first line with:
$file_name = "{$_SERVER['DOCUMENT_ROOT']}/products/{$pId}s.jpg";

However a weird problem remains. It is recognising which files exists, and which files do not exist. (correct)

So the files that do not exist, it displays noimage.gif. (correct)

However, the files it did recognise that existed, are being displayed as broken links.

[jatar_k]

to test the file you need to use the server root path as you did but to display the image you need the web root path. So...

$file_name = '/products/'.$pId.'s.jpg';
if (file_exists($_SERVER['DOCUMENT_ROOT'] . $file_name))
$test = true;
else
$file_name = 'template/noimage.gif';

[milkman_joe]

Thanks

Its working now.