Declar Classes in Header files in C++https://devzone.nordicsemi.com/f/nordic-q-a/21148/declar-classes-in-header-files-in-cHi, This may be stupid, but I can&#39;t declare classes in my .h file in keil. I have arduino library for my I2C device, but keil; does not recognize when I declare classes. Thanks.en-USTelligent Community 13Wed, 05 Apr 2017 20:10:00 GMTRE: Declar Classes in Header files in C++https://devzone.nordicsemi.com/thread/82748?ContentTypeID=1Wed, 05 Apr 2017 20:10:00 GMT137ad170-7792-4731-bb38-c0d22fbe4515:131f3b4d-c161-4481-8758-dc07d1c5983aKeton<p>Nordic SDK is written in C99 not C++. Keil has <a href="http://www.keil.com/forum/18850/">problems</a> with mixing C99 and C++ code and so far the only solution I&#39;ve found is to set c99/c++ compilation manually in options for each file separately. That said there are problems to use Nordic SDK calls in c++ code because it heavily uses extended struct initializers <code>struct foo_s foo={. bar=baz};</code>which are not implemented in ARM C++ compiler and g++.</p><div style="clear:both;"></div>