Reading Out Form Data

register_globals = Off

Since PHP 3, the following global arrays existed for form data:

• $HTTP_GET_VARS All data provided using GET

• $HTTP_POST_VARS All data provided using POST

• $HTTP_REQUEST_VARS All data provided using GET or POST, or via cookies (use not recommended)

These arrays are global; therefore, you have to use the global keyword to up level them to global scope if you use them within a function:

function processData() {
  global $HTTP_POST_VARS;
  // now you may access $HTTP_POST_VARS
}

However, these arrays can be deactivated (PHP 5 onward), as well, using this php.ini directive:

register_long_arrays = Off

Therefore, the following is the only recommended method to access form data today in PHP:

• $_GET for GET data

• $_POST for POST data

• $_REQUEST for POST, GET, and cookies (not recommended)

The keys of these arrays are the names of the form values. The $_* arrays are so-called superglobal arraysthat is, you do not have to use the global keyword to get them into global scope; they are already available within functions.

When you have decided which superglobal array to use (depending on the form's method), accessing form data is easy: $_GET[<formfieldname>] or $_POST[<formfieldname>] retrieves the value in the form element. Table 4.1 shows which data is returned for which form field type.

Form Field Types and Data Returned in $_GET/$_POST

Two remaining form field types, graphical Submit buttons and file uploads, are covered specifically later in this chapter.