Mastering Advanced Debugging Techniques in PHP

  • May 29, 2023
  • 3 min read

The world of web development is ever-evolving, and PHP remains one of the most powerful and popular server-side scripting languages around. As developers, we know that writing code is just one side of the coin. The other side involves hunting down bugs and resolving them — a task that could be daunting without the right debugging techniques. In this post, we'll explore some advanced debugging techniques in PHP to improve your productivity and code quality.

Understanding the Basics

Before we dive into advanced debugging techniques, let's start with some basic methods that can be incredibly useful.

Using var_dump() and print_r()

PHP provides two handy functions, var_dump() and print_r(), for quick and dirty debugging. These functions allow you to inspect the values and structure of variables at runtime.

        $name = "John Doe";

        $numbers = array(1, 2, 3);

Debugging Backtraces

The debug_backtrace() function provides a backtrace of function calls, which can be immensely helpful in understanding the execution flow and identifying where issues may arise.

        function a() {

        function b() {


Taking Advantage of Xdebug

Xdebug is a powerful PHP extension that offers a wide range of debugging features. Let's explore some of the key functionalities it provides.

Setting Breakpoints

With Xdebug, you can set breakpoints in your PHP code to pause the execution and inspect variables, step through code, and analyze the flow of your program.

        $name = "John Doe";
        $age = 25;

        xdebug_break(); // Breakpoint

        echo $name;
        echo $age;

Remote Debugging with Xdebug

Xdebug also supports remote debugging, allowing you to connect to your PHP application using an IDE like PhpStorm or Visual Studio Code for a seamless debugging experience.

To enable remote debugging, you need to configure Xdebug and your IDE to establish a connection.

Error Logging

Effective error handling and logging play a vital role in debugging and maintaining a robust PHP application. Let's look at how you can leverage PHP's error logging capabilities.

Configuring Error Logging

By configuring the error_reporting and log_errors directives in your php.ini file, you can redirect PHP errors to a log file for further analysis.

        error_reporting = E_ALL
        log_errors = On
        error_log = /path/to/error.log

Working with PHPUnit for Unit Testing

Unit testing is an essential part of any software development process. PHPUnit is a widely used testing framework for PHP that allows you to write and execute tests for your code.

Writing a Simple Test Case

Let's create a simple test case using PHPUnit to validate the behavior of a function.

        require 'MyClass.php';

        use PHPUnit\Framework\TestCase;

        class MyClassTest extends TestCase {
            public function testAddition() {
                $myClass = new MyClass();
                $result = $myClass->add(2, 3);

                $this->assertEquals(5, $result);


Debugging is a critical skill for PHP developers, and mastering advanced debugging techniques can greatly improve your coding experience. By understanding the basics, utilizing powerful tools like Xdebug, effectively handling errors, and incorporating unit testing, you'll be well-equipped to tackle bugs and enhance your code quality.

We hope this article has provided valuable insights into advanced debugging techniques in PHP. For more PHP-related articles and tutorials, be sure to check out our DevPicker blog.

PHP debuggingadvanced techniquesXdebugerror loggingPHPUnitunit testing