im using links like
<a href="exsample.php?1">
<a href="exsample.php?2">
<a href="exsample.php?3">
<a href="exsample.php?4">
how can i refrence the number after the question mark

Normally parameters passed via url are given a name. If your urls were formatted like this:

http://site.com/example.php?id=4

you could just grab the id variable from the url:

PHP Code:

$id = $_GET['id']; 


If you insist on not specifying the parameter name then you have one of two options (that I know of). The first would be to use .htaccess to have

example.php?1

redirect to

example.php?id=1

or you can parse the url manually:

PHP Code:

$uri = $_SERVER['REQUEST_URI'];
$len = strlen($uri);

$var;
for($i = 0; $i < $len; $i++)
{
     if($uri[$i] == '?')
     {
          $var = $uri[$i + 1];
          $i = $len;
     }
} 


You would usually have variables, but as the person above me said, you could use .htaccess to automatically add the id in.