<?php	
		if(isset($_GET['success']) === true && empty($_GET['success']) === true){
			echo 'your details have been updated!';
		}	else 	{
		if(empty($_POST) === false && empty($errors) === true)	{
			$update_data = array(
 
				'first_name' => $_POST['first_name'],
				'last_name' => $_POST['last_name'],
				'email' => $_POST['email']
			);
			update_user($update_data);
			header('Location: settings.php?success');
			exit();
 
		}	else if (empty($errors) === false)	{
			echo output_errors($errors);
		}
?>	

$update_data = array(
 
				'first_name' => $_POST['first_name'],
				'last_name' => $_POST['last_name'],
				'email' => $_POST['email']
			);

$update_data = array(
 
				'email' => $_POST['email']
				'first_name' => $_POST['first_name'],
				'last_name' => $_POST['last_name'],
			);

 
function update_user($update_data)	{
	global $session_user_id;
	$update = array();
	array_walk($update_data, 'array_sanitize');
 
	foreach($update_data as $field=>$data);	{
		$update[] = '`' . $field . '` = \'' . $data . '\'';
	}
	mysql_query("UPDATE `users` SET " . implode(', ', $update) . " WHERE `USER_id` = $session_user_id");
}
 

foreach($update_data as $field=>$data); {
 

Warning: array_walk() expects parameter 2 to be a valid callback, function 'array_sanitize' not found or invalid function name