php中未定义的索引错误是什么？

Question

错误：“注意：未定义的索引：第8行的C：\ wamp \ www \ digi \ admin \ config \ setup.php中的页面”

我的代码是：

    <?php
   #setup document
                      //host-username-password-database_name
   $db = mysqli_connect('localhost','root','','dynamic');

   if($_GET['page'] == "")
               {$pg = 'home';}
   else
               {$pg = $_GET['page'];}

   include('/functions/sandbox.php');

   include('/functions/template.php');

   $page_title =  get_page_title($db,$pg);
?>

Answer 1

$_GET['page']未定义。要正确检查是否存在，您应该使用isset()：

 if(isset($_GET['page'])) {$pg = 'home';} else {$pg = $_GET['page'];}