PHP Include and Require

PHP allows us to create various elements and functions, which are used several times in many pages. It takes much time to script these functions in multiple pages. Therefore, use the concept of file inclusion that helps to include files in various programs and saves the effort of writing code multiple times.

"PHP allows you to include file so that a page content can be reused many times. It is very helpful to include files when you want to apply the same HTML or PHP code to multiple pages of a website." There are two ways to include file in PHP.

1. include
2. require

Both include and require are identical to each other, except failure.

• include only generates a warning, i.e., E_WARNING, and continue the execution of the script.
• require generates a fatal error, i.e., E_COMPILE_ERROR, and stop the execution of the script.

Advantage

Code Reusability: By the help of include and require construct, we can reuse HTML code or PHP script in many PHP scripts.

Easy editable: If we want to change anything in webpages, edit the source file included in all webpage rather than editing in all the files separately.

PHP include

PHP include is used to include a file on the basis of given path. You may use a relative or absolute path of the file.

Syntax

There are two syntaxes available for include:

include 'filename ';
Or 
include ('filename');

Examples

Let's see a simple PHP include example.

File: menu.html

<a href="http://www.TheDeveloperBlog.com">Home</a> |   
<a href="http://www.TheDeveloperBlog.com/php-tutorial">PHP</a> |   
<a href="http://www.TheDeveloperBlog.com/java-tutorial">Java</a> |    
<a href="http://www.TheDeveloperBlog.com/html-tutorial">HTML</a>  

File: include1.php

<?php include("menu.html"); ?>
<h1>This is Main Page</h1>

Output:

Home | 
PHP | 
Java |  
HTML
This is Main Page
<
pre class='w3-code'>

PHP require

PHP require is similar to include, which is also used to include files. The only difference is that it stops the execution of script if the file is not found whereas include doesn't.

Syntax

There are two syntaxes available for require:

require 'filename';
Or 
require ('filename');

Examples

Let's see a simple PHP require example.

File: menu.html

<a href="http://www.TheDeveloperBlog.com">Home</a> |   
<a href="http://www.TheDeveloperBlog.com/php-tutorial">PHP</a> |   
<a href="http://www.TheDeveloperBlog.com/java-tutorial">Java</a> |    
<a href="http://www.TheDeveloperBlog.com/html-tutorial">HTML</a>

File: require1.php

<?php require("menu.html"); ?>
<h1>This is Main Page</h1>

Output:

Home | 
PHP | 
Java |  
HTML
This is Main Page

PHP include vs PHP require

Both include and require are same. But if the file is missing or inclusion fails, include allows the script to continue but require halts the script producing a fatal E_COMPILE_ERROR level error.

Let's understand the difference with the help of example:

Example

include.php

<?php 
	//include welcome.php file 
	include("welcome.php");
	echo "The welcome file is included.";
?>

Output:

The welcome.php file is not available in the same directory, which we have included. So, it will produce a warning about that missing file but also display the output.

Warning: include(welcome.php): failed to open stream: No such file or directory in C:\xampp\htdocs\program\include.php on line 3

Warning: include(): Failed opening 'welcome.php' for inclusion (include_path='C:\xampp\php\PEAR') in C:\xampp\htdocs\program\include.php on line 3
The welcome file is included.

require.php

<?php
	echo "HELLO";
	//require welcome.php file 
	require("welcome.php");
	echo "The welcome file is required.";
?>

Output:

In case of require() if the file (welcome.php) is not found in the same directory. The require() will generate a fatal error and stop the execution of the script, as you can see in the below output.

HELLO
Warning: require(Welcome.php): failed to open stream: No such file or directory in C:\xampp\htdocs\program\include.php on line 3

Fatal error: require(): Failed opening required 'Welcome.php' (include_path='C:\xampp\php\PEAR') in C:\xampp\htdocs\program\include.php on line 3