Entry

How to make a GoBackButton with a picture?

Feb 19th, 2008 22:03
dman, Dan Stockton, Dan Stockton, Philip Olson, Pieter W.D. Kroon, http://www.ttnr.org

A couple of ways :

First, using LIMITs will work, so :

  [go back]    : http://www.example.com/picture.php?start=10

  -current-    : http://www.example.com/picture.php?start=20

  [go forward] : http://www.example.com/picture.php?start=30

This example would have 10 pics per page and most likely use the SQL 
LIMIT statement to control output. Essentially something like this :

  // the 10 here means '10 per page'.  $start is the first
  // record pulled, the 'offset' number
  $sql = "SELECT * from photos LIMIT $start,10";

A link could be created as such, assuming no back button is to exist 
when start = 0 :

  if ($start != 0) {
    print '<a href="pics.php?start='. ($start-10) .'">go back</a>';
  }

Also, make sure $start exists, so on top of page :

  if (empty($start)) { $start = 0; }

A more detailed approach to the above can be found here :

  Building Next/Prev Buttons for Query Results (part 2) :
  http://phpbuilder.com/columns/rod20001214.php3

Or, use JavaScript :

    <a href="javascript:history.go(-1)">[ back ]</a> 

Which will go back in the users history.

or, use a global http_server_variable
  (you must define this variable first);

    <a href="<?global $HTTP_REFERER;echo $HTTP_REFERER;?>"><img 
src="the_page_you_came_from.gif"></a>

.. OR you could:

use either of the above two options with a form:

<form>
<input type="image" title="Go Back" src="image.png"
onclick="javascript:history.go(-1)">
</form>

<form action="<?$_SERVER['HTTP_REFERER'];echo $_SERVER['HTTP_REFERER'];?>">
<input type="image" title="Go Back" src="image.png">
</form>

NOTE:
(from php.net/manual)
".. you'll notice how the older predefined variables ($HTTP_*_VARS) 
still exist. As of PHP 5.0.0, the long PHP predefined variable arrays 
may be disabled with the register_long_arrays directive."

that's what it says on the  

I haven't used 5.* yet but I've looked through the changelog and it 
doesn't appear that they've gotten completely rid of the 'global 
http_server_variable' yet.

YMMV