Follow these steps to make Visual Assist consider as C/C++ files with a non-standard extension.
Changes for Visual Assist
Exit all instances of Visual Studio before editing the registry.
If your extension denotes a header file, use regedit to add the extension to ExtHeader in the following location. Remember to include the dot and terminating semicolon:
HKEY_CURRENT_USER\ Software \ Whole Tomato \ Visual Assist X \ [<IDE spec>](https://docs.wholetomato.com/default.asp?W407) \
If your extension denotes a source file that is not a header file, add the extension to ExtSource in the following location. Remember to include the dot and terminating semicolon:
HKEY_CURRENT_USER \ Software \ Whole Tomato \ Visual Assist X \ [<IDE spec>](https://docs.wholetomato.com/default.asp?W407) \
Press Rebuild on the Performance tab of the Visual Assist options dialog and restart your IDE.
Changes for Visual Studio
Make version-specific changes to your IDE as well:
Visual Studio 2010 and newer
Add your extension to:
Tools | Options | Text Editor | File Extension | Microsoft Visual C++
Also add your extension to:
Tools | Options | Projects and Solutions | VC++ Project Settings | Extensions To Include