The Drupal coding standards docs are a great reference for developers, but there’s also an automated way of checking your code: the Coder module. Here’s how it works:

1. Install

Copy to sites/all/modules and enable the usual way. Now you have a new link in Navigation:

2. Choose reviews

Click that link, then select exactly what you want the Coder module to do on this page:

3. Targets

Select what you’d like to review, there are many different options:

4. Submit

Submit, then view the results: