PHP contains


PHP include and require statements

In PHP, you can insert the contents of a file into the PHP file before it is executed by the server.

include and require statements are used to insert useful code written in other files into the execution flow.

include and require are identical except for how they handle errors:

  • require generates a fatal error ( E_COMPILE_ERROR), the script will stop executing after the error occurs.

  • include generates a warning (E_WARNING) and the script will continue execution after the error occurs.

So if you want to continue execution and output results to the user even if the included file is missing, then use include. Otherwise, in frameworks, CMS, or complex PHP application programming, always use require to reference key files to the execution flow. This helps improve application security and integrity in the event that a critical file is accidentally lost.

Including files saves a lot of work. This means you can create standard header, footer or menu files for all web pages. Then, when the header needs updating, you simply update the header include file.

Syntax

include 'filename';
or
require 'filename';

PHP include and require statements

Basic example

Suppose you have a standard page header file named "header.php". To reference this header file in the page, please use include/require: 

<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<?php include 'header.php'; ?>
<h1>欢迎来到我的主页!</h1>
<p>一些文本。</p>
</body>
</html>

Example 2

Suppose we have a Standard menu file used in pages.

"menu.php":

All pages in the 
echo '<a href="/">主页</a>
<a href="/html">HTML 教程</a>
<a href="/php">PHP 教程</a>';
website should reference this menu file. The following is the specific approach: 
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<div class="leftmenu">
<?php include 'menu.php'; ?>
</div>
<h1>欢迎来到我的主页!</h1>
<p>一些文本。</p>
</body>
</html>

Example 3

Suppose we have an include file that defines variables ("vars.php "): 

<?php
$color='red';
$car='BMW';
?>
These variables can be used in the calling file: 
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<h1>欢迎来到我的主页!</h1>
<?php 
include 'vars.php';
echo "I have a $color $car"; // I have a red BMW
?>
</body>
</html>