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Php code for include file

Why use Comments?

  • If you don’t work on the source code for some time, it’s easy to forget what the code does. Commenting the source code helps remember what the code does.
  • Commenting source code is also very important when multiple developers have to work on the same project. The changes made by one developer can be easily understood by other developers by simply reading the comments.
  • As the best practice, you must have 3 lines of comments for every 10 lines of code

In this tutorial, you will learn-

  • PHP Comments
  • PHP Include & PHP Include_once
  • Example : Include / Include_once
  • PHP Require & PHP require_once
  • Example : Require
  • PHP include vs require

PHP Comments

The diagram below shows a PHP file with both multiple line and single line comments

PHP Example

PHP Include & PHP Include_once

The “include” php statement is used to include other files into a PHP file.

It has two variations, include and include_once.  Include_once is ignored by the PHP interpreter if the file to be included.

The include statement has the following syntax

The include_once statement has the following syntax


  • “Include/include_once” is the statement that includes file
  • “'file_name'” is the name of the file to be included.

Example : Include / Include_once

Suppose you are developing a website that contains the same navigation menu across all the pages.

You can create a common header then include it in every page using the include statement Let’s see how this can be done.

  • We will create 2 files names
  • header.php, index.php

Below are the codes for; header.php


About us


Contact Us


The header page above will output

PHP Require & PHP require_once

The require statement has two variations, require and require_once.

The require/require_once statement is used to include file.

Require_once is ignored if the required file has already been added by any of the four include statements.

It has the following syntax


  • “require/require_once” is the statement that includes file
  • “'file_name'” is the name of the file to be included.

Example : Require

Suppose we are developing a database powered application.

We can create a configuration file that we can include in all pages that connect to the database using the require statement. config.php

Let’s now look at the sample code that requires the config file. Pages_model.php

Php include vs require

The difference between include / require

Include Require
Issues a warning when an error occurs Does not issue a warning
Execution of the script continues when an error occurs Execution of the script stops when an error occurs.

  Generally, it’s recommended using the include statement so that when an error occurs, execution of the script continues to display the webmaster email address or the contact us page.

The require statement should be used if the entire script cannot run without the requested file.

The “include” and “require” statements can be used at any line in the source codes where you want the code to appear.