Recently at my internship I've been writing quite a bit of PHP. The language itself is OK (I mean it does the job), but it's beginning to feel like a relic of a bygone era - especially when it comes to debugging. Up until recently I've been stuck with using echo() and var_dump() calls all over the place in order to figure out what's going on in my code - that's the equivalent of debugging your C♯ ACW with Console.WriteLine() O.o

Thankfully, whilst looking for an alternative, I found xdebug. Xdebug is like visual studio's debugging tools for C♯ (albeit a more primitive form). They allow you to add breakpoints and step though your PHP code one line at a time - inspecting the contents of variables in both the local and global scope as you go. It improves the standard error messages generated by PHP, too - adding stack traces and colour to the output in order to make it much more readable.

Best of all, I found a plugin for my primary web development editor atom. It's got some simple (ish) instructions on how to set up xdebug too - it didn't take me long to figure out how to put it to use.

I'll assume you've got PHP and Nginx already installed and configured, but this tutorial looks good (just skip over the MySQL section) if you haven't yet got it installed. This should work for other web servers and configurations too, but make sure you know where your php.ini lives.

XDebug consists of 2 components: The PHP extension for the server, and the client that's built into your editor. Firstly, you need to install the server extension. I've recorded an asciicast (terminal recording) to demonstrate the process:

(Above: An asciinema recording demonstrating how to install xdebug. Can't see it? Try viewing it on asciinema.org.)

After that's done, you should be able to simply install the client for your editor (I use php-debug for atom personally), add a breakpoint, load a php page in your web browser, and start debugging!

If you're having trouble, make sure that your server can talk directly to your local development machine. If you're sitting behind any routers or firewalls, make sure they're configured to allow traffic though on port 9000 and configured to forward it on to your machine.