PHP include() | Call Another PHP File to Execute

The PHP include() function is used when we need to include an external PHP file in a PHP script to execute the script available in that external file in the current PHP file. For example:

<?php
   include("header.php");
   echo "Hey, PHP is Fun!<BR>";
   echo "Is not it?";
?>

The file header.php is available in the current directory and contains the following script:

<?php
   echo "-------Welcome to Company.com---------<HR>";
?>

Therefore, the output of the above example on the include() function in PHP is shown in the snapshot given below:

Now the question is, what if the included file does not exist? Let us find out the answer using the example given below:

<?php
   include("unknown.php");
   echo "Hey, PHP is Fun!<BR>";
   echo "Is not it?";
?>

Now the output is:

That is, since the file unknown.php does not exist, you are seeing the error. But the current script after the include() function has still been executed. Use error_reporting(0) to turn off error reporting.

PHP include() Syntax

The syntax of the include() function in PHP is:

include "file";

include 'file';

include("file");

include('file');

Note: The include() function produces a warning (E_WARNING) message if the specified file does not exist, and the script continues its execution.

Why use include() in PHP?

I do not know what your purpose is for using the function include(). But, with the use of the include() function, the same script need not be written for every file. That is, if some PHP scripts like header and footer content are available in multiple files of your web application. Then it is better to go with the include() function to write the header and footer content at once, in two PHP files. And include these two files in each to avoid writing them multiple times.

Another benefit is that if you want to change the content of the footer and/or header, then just change the content of those two files. It reflects the change in the whole application or all files, where these files are included. For example:

<?php error_reporting(0); ?>
<!DOCTYPE html>
<html>
<head>
   <style>
      * {box-sizing: border-box;}
      body {margin: 0;}
      .head {padding: 22px 0; font-size: 1.4em; text-align: center; background: maroon; color: white;}
      .navigation {display: flex; background-color: peru;}
      .navigation a {color: white; padding: 12px 16px; text-decoration: none; text-align: center;}
      .cont {display: flex; flex-wrap: wrap; min-height: 540px;}
      .menu {flex: 20%; background-color: #ccc; padding: 16px;}
      .content {flex: 60%; padding: 16px;}
      .right {flex: 20%; background-color: grey; color: white; padding: 16px;}
      .foot {padding: 22px 0; text-align: center; background: maroon; color: white;}
      @media screen and (max-width: 600px) {.cont, .navigation {flex-direction: column;}}
   </style>
</head>
<body>

   <?php include 'header.php'; ?>
   
   <div class="cont">
   
      <div class="menu">
         <p>----Some Menu----</p>
      </div>
      
      <div class="content">
         <p>Content of the Page...</p>
      </div>
      
      <div class="right">
         <p>----Right Side----</p>
      </div>
      
   </div>
   
   <?php include 'footer.php'; ?>

</body>
</html>

The content of the header.php file is:

<div class="head">fresherearth</div>
   <div class="navigation">
      <a href="#">MenuOne</a>
      <a href="#">MenuTwo</a>
      <a href="#">MenuThree</a>
      <a href="#">MenuFour</a>
      <a href="#">MenuFive</a>
   </div>

And the content of the footer.php file is:

<div class="foot">
   <p>Some texts/links...</p>
</div>

Now the output should be:

PHP Online Test

« Previous Tutorial Next Tutorial »