The Arduino IDE supports multiple files by adding more tabs. If you use INO files you’re only adding one at a time, but if you use C/C++ header and source files it’s two at time.

Although Arduino's programming language is based on C++, you won't be able to use all of its commands. But, you can still use objects in Arduino's IDE, which are a fundamental aspect of C++.

The Arduino development team has recently unveiled the latest version of their Integrated Development Environment (IDE), version 2.3, which brings a host of improvements to the platform.