Variables and session variables

[MilesDependent]

Hi

Have a quick query...

I am developing a website that provides information about cars in a particular city (not really cars, but the principles will be the same).

The page which displays the cars is basically: show_cars.php?city=nyc&car=001

The first time a user loads a NYC page, the show_cars script retrieves the NYC cars from mysql and stores them in an array called nyc_cars_array. The cars are then listed in a select/option dropbown box. I have set up the arrays to prevent the need for continuing to pull out the list of NYC cars from the database whenever the page is reloaded.

A real quick synopsis of the code would be:

$city = $HTTP_GET_VARS['city'];

Then assuming the city was NYC I would want to check to see if the NYC array had been set.

if (!isset($HTTP_SESSION_VARS['nyc_car_array']))
{
$nyc_car_array = get_car_array(nyc);
$HTTP_SESSION_VARS['nyc_car_array'] = $nyc_car_array;
}

However, I do not want to have to create one of the above if-isset arguments for each city. Is there some way I can insert the $city variable into the argument?

For instance, it would be:

if (!isset($HTTP_SESSION_VARS['$city_car_array']))
{
$$city_car_array = get_car_array($city);
$HTTP_SESSION_VARS['$city_car_array'] = $$city_car_array;
}

The above clearly does not work as I have just substituted $city for NYC. There must be someway to do this.

Thanks,
MD

[maybl8r03]

First off, $HTTP_SESSION_VARS and $HTTP_GET_VARS can now be replaced with a $SESSION and $GET supervariable.

Secondly, '$abc' and "$abc" (notice the quotes) are quite different, the later actually parses the abc variable into it's value.

Try this:

$abc = "123";
echo '$abc';
echo "<br />"
echo "$abc";

Using the double ($$) variable sign should be limited to very controlled instances - as it's quite difficult to debug (when you have to deal with a lot of variables) - The following code would work just as readilly I guess:

$citytoview = $_GET["city"];
if (!isset($_SESSION[$citytoview]))
{
   $_SESSION[$citytoview] = get_car_array($citytoview);
}

[nelustr]

An exemple is here: http://www.xtrax.ro/php/cars/cars.php

You can register the session variables.

session_start();
if (!isset($GLOBALS["is_log"])){
	 $is_log=1;
   session_register("is_log","nyc_cars_array");
	 include("setCars.inc.php");
	 }
?>
<form method="POST">
 Please select:<select name="car" onChange="submit()">
<?php
  reset($nyc_cars_array);
	while (list($id,$val)=each($nyc_cars_array)){
	      $selected="";
	      if ($id==$car) $selected="selected";
				echo "<option value=\"$id\" $selected>$val</option>\n";
				}
?>
 </select>
 <input type="submit" name="go" value="Go">
</form>

here is the setCars.inc.php code

unset($nyc_cars_array);
$nyc_cars_array[1]="Car 1";
$nyc_cars_array[2]="Car 2";
$nyc_cars_array[3]="Car 3";
$nyc_cars_array[4]="Car 4";
echo "nyc_cars_array defined<BR/>";

Notes:
Check if the register_globals is On. This variable is seted in httpd.conf for Apache

[MilesDependent]

Thank you both very much for the replies. I will try out what you have said, and let you know how I went.

Rgds
MD