Using require to Include Functions¶

I’ll show you a few more tricks with functions in a second. But right now, let’s improve our contact.php page we started earlier. First, I want to be able to have a header that reads “Helping you find your new best friend from over 500 pets.”:

<h1>
    Helping you find your new best friend from over 500 pets.
</h1>

Except, I want the number 500 to be dynamic, reflecting the true number of pets we have in our pets.json file. I’ll do this by calling our get_pets() function and passing it to PHP’s count function, which will tell us how many items are in that array:

<h1>
    Helping you find your new best friend from over <?php echo count(get_pets()); ?> pets.
</h1>

But when we try it, it blow up big time!

Fatal error: Call to undefined function get_pets() in /php1/contact.php on line 2

Hmm, the function works in index.php, but not in contact.php. Clearly, the difference is that get_pets() actually lives in index.php. And that’s totally correct. Even though it sits next to index.php, when PHP executes the contact page, it has no idea what functions or variables might live in the index file. These two files exist in perfect isolation.

So is there a way to load the functions in index.php from contact.php? Of course! The answer is with the require statement, which tells PHP to load & parse the contents of some other file. Require index.php at the top of the file:

<?php
// contact.php
require 'index.php';
?>

<h1>
    Helping you find your new best friend from over <?php echo count(get_pets()); ?> pets.
</h1>

When we try it, it works... sort of. At the bottom of the page, we see our sentence with the correct pets count. But above it is the entire index.php page, which we did not want. Adding require made using the get_pets() function possible, but it also brought in all the HTML from the index page as well. What can we do?

Let’s create a new file called functions.php, which I’ll put in a lib/ directory for organization since this PHP file isn’t meant to be a page that’s accessed directly like our index and contact files. Now, move the get_pets() function in here, being sure to remember your opening PHP tag:

<?php
// lib/functions.php

function get_pets()
{
    $petsJson = file_get_contents('data/pets.json');
    $pets = json_decode($petsJson, true);

    return $pets;
}

<?php
// index.php
require 'lib/functions.php';
// ...

<?php
// contact.php
require 'lib/functions.php';
// ...