CGI

Parameters

GET

$param_value = $_GET['param_name'];

• If the parameter was not sent, the value retrieved is NULL.
  

POST

$param_value = $_POST['param_name'];

• If the parameter was not sent, the value retrieved is NULL.

Environment variables

$url       = $_SERVER['REQUEST_URI'];

$base_url  = $_SERVER['SCRIPT_NAME'];
$url_query = $_SERVER['QUERY_STRING'];

HTML forms

Text field

• If the field is empty, the value retrieved is an empty string.
  

Radio button

• If no item was selected, the value retrieved is NULL.
  

Check box

• If the field is unchecked, the value retrieved is NULL.
• If the field is checked, the value retrieved is "on".

Single-selection list

• If no item was selected, the value retrieved is NULL.
  

Multiple-selection list

• In the HTML form, the name of the list must be followed by []
  

<select name="field_name[]" size="10" multiple>

• The value is retrieved as an array of strings.
• If no items were selected, the value retrieved is NULL.