PHP File Inclusion Issue: File not Executing as Expected

Question

I'm encountering an issue where a particular PHP file, custom_functions.php, is not being executed within my project, resulting in unexpected behavior.

Problem Context File Structure:

project/
│
├── index.php
├── includes/
│   ├── custom_functions.php

Here is a simplified version of the index.php file:

<?php

    // Trying to include custom functions file
    include 'includes/custom_functions.php';

    // Using a function from the custom functions file
    $result = customFunction();
    echo "<p>Result: $result</p>";
?>

And the custom_functions.php file:

    <?php
    function customFunction() {
    return "This function should return a customized value.";
    }
    ?>

The issue arises when attempting to include custom_functions.php in index.php. Despite the include statement, the customFunction() isn't being recognized or executed as expected. No errors are displayed, but the function doesn't seem to be available within index.php.

I've tried several solutions:

Checked File Paths: Verified that the file paths are accurate and the custom_functions.php file is in the correct directory.

Error Reporting: Set error_reporting(E_ALL) and ini_set('display_errors', 1) in both files but no errors were displayed.

Direct Function Call: When calling the customFunction() directly within custom_functions.php, it works fine, indicating that the file is being included.

Request for Assistance I'd greatly appreciate any insights or suggestions on why the included file's functions aren't accessible within index.php. Has anyone encountered a similar issue or might know what could be causing this unexpected behavior?

Thanks in advance for any help!