C++-ARUW-Style-Guide.md

@@ -11,13 +11,14 @@ We follow the [Google C++ style guide](https://google.github.io/styleguide/cppgu
 | Functions                                 | `camelCase()`                       | |
 | Header guards                             | `FILE_NAME_HPP_`                    | If the file is named `FileName.hpp`. |
 | `endif` comment for header guard          | `endif  // FILE_NAME_HPP_`          | The `endif` comment at the end of the header file should match the `ifndef` at the beginning of the header file. |
-| class file name                           | `ClassName.hpp` and `ClassName.cpp` | Previously we  used the format `class_name.hpp` and `class_name.cpp`. |
+| class file name                           | `class_name.hpp` and `class_name.cpp` | Previously we  used the format `ClassName.hpp` and `ClassName.cpp`. |
 | file without a class                      | `file_name.hpp` and `file_name.cpp` | |
 | Constants                                 | `UPPERCASE_AND_UNDERSCORE`          | |
 | Comment on the closing bracket of a class | `// ClassName`                      | For an example, see [this example](#example-class). |
 
 ### Additional general naming rules:
 - While naming, avoid using numbers in variables when appropriate.
+- For interfaces (which can be defined as classes that only have pure virtual functions), use the naming convention `ClassNameInterface`.
 
 ## Spacing