Learn How to Debug PHP with Xdebug and VsCode

You must pay attention to a few things when developing web applications to deliver a smooth end product. Good developers follow the development best practices, including testing, debugging, etc., while creating robust apps.

This article discusses the PHP debug concepts and coding techniques. So read on to learn more about debugging PHP.

You can start debugging without any configuration. But, this is only suggested when you need to connect to an existing Web Server with Xdebug configured or want to run and debug a PHP script rapidly.

Let’s start with the basic level, where you tend to write PHP code using print_r(), var_dump() commands to debug the output of the written code. We have many PHP debugging tools, that let user urges to fix the errors during coding, and some functions that show you the correct output or errors/warnings in case of code failure. Although this PHP debugging technique is basic, it is still in use.

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Error Logs in PHP

When you are working in a dev environment on any web hosting for PHP, you must turn on error reporting to check if the PHP error logs are being generated. You can enable/disable error logs from php.ini and individual php files.

The other best practice is to create a configuration file in your project. And you can enable it in the php.ini file. But remember to remove the semicolon (;) from each line.

error_reporting = E_ALL & ~E_NOTICE

error_reporting = E_ALL & ~E_NOTICE | E_STRICT

error_reporting = E_COMPILE_ERROR|E_RECOVERABLE_ERROR|E_ER… _ERROR

error_reporting = E_ALL & ~E_NOTICE

To enable PHP error logging for the current call in the individual file, insert the following code :

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

But still, you need to enable this line in the php.ini file for reporting parse errors:

display_errors = on

The above techniques are useful in any environment. You may sometimes forget to revert the dev settings when you have finished your app and uploaded it to production servers.

In this case, you can create a configuration file that includes the conditions in which you display and log errors. You can write the following code for error checking in PHP:

:

define('DEBUG', true);

error_reporting(E_ALL);



if(DEBUG == true)

{

       display_errors(true);

       log_errors(false);

}

else

{

      display_errors(false);

       log_errors(true);

}

You can define env in the above method and can set your required conditions. For example, when you don’t want to log errors but just want to display them in the browser.

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Here are the different methods for error checking in PHP that you can use to debug php scripts, errors, and warnings.

// Turn off all error reporting

error_reporting(0);



// Report simple running errors

error_reporting(E_ERROR | E_WARNING | E_PARSE);



// Reporting E_NOTICE can be good too (to report uninitialized

// variables or catch variable name misspellings ...)

error_reporting(E_ERROR | E_WARNING | E_PARSE | E_NOTICE);



// Report all errors except E_NOTICE

error_reporting(E_ALL & ~E_NOTICE);



// Report all PHP errors (see changelog)

error_reporting(E_ALL);



// Report all PHP errors

error_reporting(-1);



// Same as error_reporting(E_ALL);

ini_set('error_reporting', E_ALL);

What is PHP Debug Driven Development?

Earlier, I was unsure of the debug-driven development (DDD) term, but I got this idea from a debugger friend. His code contained multiple breakpoints, and he went through each line response till he got the desired output.
Don’t be confused with breakpoints, as I will demonstrate them. DDD has a similar flow to TDD, where you first define all the PHP debugging techniques for configuration and then write the code to debug if any errors arise.
Once you have an idea of DDD, you should learn about Xdebug, which helps you understand the concept of PHP debug-driven development. Running PHP with Xdebug gives you full insights into errors, responses, and code coverage.

What Is Xdebug?

Imagine you’ve written your code, and the code breaks just when you compile it. And the worst part is that you can’t identify what went wrong. Xdebug is your savior here.

Xdebug is a PHP extension that helps developers debug and smoothen the development of their projects to watch for errors and resolve them. It upgrades PHP’s var_dump() function and adds stack traces for notices, warnings, errors, and exceptions.

Xdebug uses the DBGp debugging protocol and gives debugging and profiling capabilities. It allows us to add breakpoints and stop the code execution at every breakpoint to see variables output in only one code iteration.

So Xdebug lets you save your time, which is otherwise lost in code debugging. Without Xdebug, you must refresh the page to see the output again. You can also set breakpoints independent methods to see which one is causing issues.

Also, you can add as many breakpoints as you want in the code and use a PHP debugger to check each code line by line.

Install Xdebug in PHP

Now it’s time to install Xdebug in PHP. There are a few options through which you can install Xdebug.

Windows:

For windows users, Xdebug is providing a wizard tool through which you can download the related .dll file. For this, first, create a PHP file in folder, and add the following line of code:

<?php

phpinfo();

?>

Run the file in the browser. You will see the PHP information. Copy the details and put them in the wizard tool and click on Analyze my phpinfo() output button.

This will give you the following output:

Now, download the .dll files and follow the above-mentioned instructions to put files in the xampp/php/ext directory. Next, follow step 3 to enable Xdebug in the php.ini file, and finally restart the webserver.

MAC

You can install PHP7 Xdebug using pecl extension:

pecl install xdebug

Linux

On Linux distribution like Debian, you can use Sudo to install Xdebug in PHP:

sudo apt install php-xdebug;

Now, open the file etc/php/7.0/mods-available/xdebug.ini and add the following code to enable Xdebug:

xdebug.profiler_enable_trigger = 1

xdebug.profiler_enable = 0

xdebug.remote_enable = 1

xdebug.profiler_output_dir = "/tmp"

Now, restart the Apache2 server.

sudo service apache2 restart;

GIT

You can also clone it from GitHub.

git clone git://github.com/xdebug/xdebug.git

After installing Xdebug, open the php.ini file, and enable the extension.

zend_extension="xdebug.so"

Now, check the PHP version using the command `php -v`. You will see the Xdebug version installed with PHP.

$ php -v

PHP 7.2.0RC6 (cli) (built: Nov 23 2017 10:30:56) ( NTS DEBUG )

Copyright (c) 1997-2017 The PHP Group

Zend Engine v3.2.0-dev, Copyright (c) 1998-2017 Zend Technologies

 with Xdebug v2.6.0-dev, Copyright (c) 2002-2017, by Derick Rethans

Configure Xdebug in VSCode

If you want a smooth workflow with Xdebug, you can integrate it into your favorite IDE like phpstorm, Zend studio, and VScode. Let’s configure Xdebug in Visual Studio Code to debug PHP.

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There is a popular VSCode PHP extension called php debug. You can find it in the extension window and install it.

After installation, you must reload the VSCode window. Now, again run phpinfo(); method in any PHP file to check if Xdebug is enabled or not.

Now click on the debug console tab and click on add configuration.

Now, you must select the environment which is PHP. VSCode will now add a launch.json file in the root directory.

Finally, add the runtimeExecutable property to the list after port:

"runtimeExecutable": "C:\\xampp\\php\\php.exe"

Save the launch.json file. Open the debug mode tab, and click on the green debug button to start the debugging option.

You will now see few items in the window, through which you can select what logs Xdebugger will show like:

• Notices
• Warnings
• Errors
• Exceptions
• Everything

Navigate to the Debug Console section which shows you the details of errors and the debug execution buttons on top.

At this point, you can add breakpoints on the lines of code that you need to debug. Note that Xdebug will add the PHP debug script name with the line number on the bottom left section:

You can run the application in the browser, and then read the code line by line, to see the errors and debug them properly. Also, you need to remind a few shortcut functions keys to move through functions and line of codes:

F5:  Continue Debugging

F10: Step Over

F11: Step into

Shift + F11: Step out

Xdebug Profiling

Xdebug also provides profiling of code just like other profiling tools, Blackfire and Tideways. If you want to use the profiling option, then you must enable it in the php.ini file.

xdebug.profiler_enable=1

xdebug.profiler_output_dir="C:\xampp\tmp"

Now, open a file and start entering all the profiling logs.

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Final Words

Debugging is an important aspect of coding; without it, you can’t tell what went wrong with your code.

This article has demonstrated how to enable PHP to debug with Xdebug and configure it in VSCode. You can also integrate it in Eclipse, PHPstorm, and other IDEs.

The best practice is to set up your debugging environment before writing the code. If you are developing a complex application containing thousands of lines of code, you will need a PHP debugger to find errors and warning signs.

If there is anything you want to know more about, post your queries and suggestions in the comments section below.