在同一個網站的不同網頁中，可能常常出現重複的內容
比如header、footer之類的
如果每次修改都需要一次大量修改
肯定會造成不小的麻煩
因此利用require和include省去這樣的麻煩
並且運用在網頁切版
這篇文章示範了固定頁首頁尾，僅變動內容的切版方式

require與include

require與include的差別

require的Script如果有缺失，就會整個檔案不能跑
include的Script如果有缺失，只會顯示警告

同樣的內容，如Header、footer之類的一直會重複用到，我們用include簡短我們的程式碼
先建立像下面一樣的網站結構：

網頁切版範例

index.php 作為框架，裡面include了固定的header.php以及footer.php，除此之外還有變動的內容content/...

<!DOCTYPE>
<html>
    
    <head>
        <title>網頁切版範例</title>
        <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.5.3/dist/css/bootstrap.min.css" integrity="sha384-TX8t27EcRE3e/ihU7zmQxVncDAy5uIKz4rEkgIXeMed4M0jlfIDPvg6uqKI2xXr2" crossorigin="anonymous">
        <script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.5.3/dist/js/bootstrap.bundle.min.js" integrity="sha384-ho+j7jyWK8fNQe+A12Hb8AhRq26LrZ/JpcUGGOn+Y7RsweNrtN/tE3MoK7ZeZDyx" crossorigin="anonymous"></script>
    </head>
    <body>
        <div>
        <?php include('header.php');?>
        </div>
        <div class="container-fluid">
        <?php 
$current_page = 'homepage';
            if(array_key_exists('page',$_GET)){
                $current_page = $_GET['page'];
            }

switch ($current_page) {
    default:
        include 'content/homepage.php';
        break;
    case 'about':
        include 'content/about.php';
        break;
    case 'products':
        include 'content/products.php';
        break;

}?>
        </div>
        <div>
        <?php include('footer.php');?>
        </div>
        
    </body>
    
</html>

heaer.php中我套用了bootstrap中的模板，並且改成我想要的樣子。這部分的重點在於href的部分，我們會用到$_GET這個函數裡面儲存的變數，變數名稱記得一致。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Your Website Name</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="index.php?">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="index.php?page=about">About<span class="sr-only">(current)</span></a>
      </li>
        <li class="nav-item">
        <a class="nav-link" href="index.php?page=products">Products</a>
      </li>
      ...
</nav>

footer.php 一樣用了bootstrap的模板

<!-- Footer -->
<footer class="page-footer font-small blue">

  <!-- Copyright -->
  <div class="footer-copyright text-center py-3">© 2020 Copyright:
    <a href="#"> Your Website</a>
  </div>
  <!-- Copyright -->

</footer>
<!-- Footer -->