Reference Styleguide for different languages from Google
from the Page:
google-styleguide – Style guides for Google-originated open-source projects
“Style” covers a lot of ground, from “use camelCase for variable names” to “never use global variables” to “never use exceptions.” This project holds the style guidelines we use for Google code. If you are modifying a project that originated at Google, you may be pointed to this page to see the style guides that apply to that project.