PHP register_global = On/Off

<input type="text" name="txtName">

<?php
echo $txtName;
?>

<?php
echo $sitename;
?> 

<input type="text" name="txtName">

<?php
echo $_POST["txtName"]
?>

<?php
echo $_GET["sitename"];
?> 

<?php
//*** Register Global =On/Off Function ***//
$phpVersion = phpversion();
list($v_Upper,$v_Major,$v_Minor) = explode(".",$phpVersion);

if (($v_Upper == 4 && $v_Major < 1) || $v_Upper < 4) {
	$_FILES = $HTTP_POST_FILES;
	$_ENV = $HTTP_ENV_VARS;
	$_GET = $HTTP_GET_VARS;
	$_POST = $HTTP_POST_VARS;
	$_COOKIE = $HTTP_COOKIE_VARS;
	$_SERVER = $HTTP_SERVER_VARS;
	$_SESSION = $HTTP_SESSION_VARS;
	$_FILES = $HTTP_POST_FILES;
}

if (!ini_get('register_globals')) {
	while(list($key,$value)=each($_FILES)) $GLOBALS[$key]=$value;
	while(list($key,$value)=each($_ENV)) $GLOBALS[$key]=$value;
	while(list($key,$value)=each($_GET)) $GLOBALS[$key]=$value;
	while(list($key,$value)=each($_POST)) $GLOBALS[$key]=$value;
	while(list($key,$value)=each($_COOKIE)) $GLOBALS[$key]=$value;
	while(list($key,$value)=each($_SERVER)) $GLOBALS[$key]=$value;
	while(list($key,$value)=@each($_SESSION)) $GLOBALS[$key]=$value;
	foreach($_FILES as $key => $value){
		$GLOBALS[$key]=$_FILES[$key]['tmp_name'];
		foreach($value as $ext => $value2){
			$key2 = $key."_".$ext;
			$GLOBALS[$key2]=$value2;
		}
	}
}
?>