Is $HTTP_XXX_VARS different from $_XXX in PHP?

Question

Does the following code make sense?:

$t_server = isset( $_SERVER ) ? $_SERVER : $HTTP_SERVER_VARS;

As I understand, $HTTP_XXX_VARS is same with $_XXX, except $HTTP_XXX_VARS is deprecated. Thus, I don't understand the code above.

Is there a case that two variables are different in an old system in which $HTTT_XXX_VARS is not considered as deprecated?

Answer 1

$HTTP_SERVER_VARS and $_SERVER are different variables (if both are set). They initially contain the same values but, being different, the changes that the script does on one of them do not affect the other.

The superglobals ($_GET, $_POST, $_SERVER etc) were introduced on PHP 4.1. The long named variables ($HTTP_GET_VARS, $HTTP_SERVER_VARS etc) were deprecated on PHP 4.1 and they were removed on PHP 5.4.

PHP 5.0 introduced the configuration setting register_long_arrays that was used to tell PHP to create (or not) the old long-named variables ($HTTP_GET_VARS and the rest). The setting was deprecated on PHP 5.3 and removed altogether on PHP 5.4 (together with the long-named arrays).

As you can see, between PHP 4.0 and PHP 5.4 one or both versions of these variables were available to the programmer.

The line:

$t_server = isset( $_SERVER ) ? $_SERVER : $HTTP_SERVER_VARS;

takes advantage of the new superglobal variable $_SERVER, if available (on PHP >= 4.1), but it falls back to the old $HTTP_SERVER_VARS if it runs on older PHP. It was probably written years ago, while PHP 4 was still in use on a lot of servers.

Except on the unlikely case when you are stuck with PHP 4.0, you can safely change the above line to:

$t_server = $_SERVER;

or just use $_SERVER instead of $t_server everywhere.