index.php 中显示多个未定义的索引

Question

我正在学习使用 php 制作动态网页。我通过教程创建了我的网站。它工作得很好，除了以下几行不断出现在我的 index.php 页面上：

注意：未定义索引：第 6 行 C:\xampp\htdocs\janewoo_new\index.php 中的页面 注意：未定义索引：第 8 行 C:\xampp\htdocs\janewoo_new\index.php 中的页面 注意：未定义索引：第 10 行 C:\xampp\htdocs\janewoo_new\index.php 中的页面 ...

这是我在 index.php 上的代码：

<?php

include("includes/header.html");
include("includes/navbar.html");

if($_GET['page']=="traditional_teampage.html"){
include("includes/traditional_teampage.html" );
}else if($_GET['page']=="traditional_mediapage.html"){
include("includes/traditional_mediapage.html");
}else if($_GET['page']=="traditional_faqpage.html"){
include("includes/traditional_faqpage.html");
}else if($_GET['page']=="traditional_casepage.html"){
include("includes/traditional_casepage.html");
}else if(isset($_GET['page'])=="consumer-proposal.html"){
include("includes/consumer-proposal.html");
}else if($_GET['page']=="bankruptcy.html"){
include("includes/bankruptcy.html");
}else if($_GET['page']=="community.html"){
include("includes/community.html");
}else if($_GET['page']=="traditional_contactpage.html"){
include("includes/traditional_contactpage.html");
}else{
include("includes/traditional_home.html");
}

include("includes/footer.html");

?>

我按照其他人的答案中的描述放置了 isset() ，但是按钮都转到了同一页面的第一页。我更像是一个设计师而不是一个程序员，我正在尽我最大的努力学习 php。希望可以有人帮帮我。非常感谢。

Answer 1

要更正警告更改：

if($_GET['page']=="traditional_teampage.html"){

变成：

if(isset($_GET['page']) and $_GET['page']=="traditional_teampage.html"){

---

还要考虑这种结构的 switch/case 语句

http://www.php.net/manual/en/control-structures.switch.php

switch((isset($_GET['page'])) ? $_GET['page'] : null)
{
  case 'traditional_teampage.html':
  case 'traditional_mediapage.html':
  case 'traditional_faqpage.html':
  case 'traditional_casepage.html':
  case 'consumer-proposal.html':
  case 'bankruptcy.html':
  case 'community.html':
  case 'traditional_contactpage.html':
    include('includes/' . $_GET['page']);
    break;
  default:
    include("includes/traditional_home.html");
    break;
}

甚至是一个简单的in_array()“白名单”供您包含。

if(isset($_GET['page']) and in_array($_GET['page'],array(
  'traditional_teampage.html',
  'traditional_teampage.html',
  'traditional_mediapage.html',
  'traditional_faqpage.html',
  'traditional_casepage.html',
  'consumer-proposal.html',
  'bankruptcy.html',
  'community.html',
  'traditional_contactpage.html'
)))
{
  include('includes/' . $_GET['page']);
}
else
{
  include("includes/traditional_home.html");
}