Php 未定义索引：操作

高亮显示的行是第24行

注意：第24行C:\xampp\htdocs\authors.php中的未定义索引：操作

  **if($_GET['action'] == "list") {**
        $current = "members";
        $list = "members";
    }
    else if($_GET["list"] == "authors") $current = "authors";
    else $current = "members";

---

首先检查是否设置了

$\u GET['action']

if(isset($_GET['action'])) {

    if($_GET['action'] == "list") {
        $current = "members";
        $list = "members";
    } else if($_GET["list"] == "authors") {
        $current = "authors";
    } else {
        $current = "members";
    }

}