error: 'YourClassName' was not declared in this scope - SOLVED

Projects Programming
1

I just chased down a problem that was making me crazy.

I had a class defined in an external library, but when I tried to make a function that would accept it as an argument, I would get the 'myTypeName was not declared in this scope' error.

The problem was, I was including my header file with "myType.h" instead of <myType.h>.

The Arduino pre-processor seems to use the first "" included header file as a place to drop all the forward reference prototypes it makes when it turns your sketch.pde file into a sketch.cpp file.

Since my include happened AFTER the first #include "header.h", the prototypes that referenced myType happened prior to the include where they were defined.

Changing my include to <myType.h> and moving it up so it occurred prior to any "otherheader.h" style includes fixed things right up.

Critical to debugging this was setting build.path=/tmp/build and build.verbose=true so i could see what was going on.

I couldn't find this referenced on the internets, so here you go!

-Scott

2

My understanding is that #include "lib.h" is used when the library is in the same folder as the sketch, whereas #include <otherlib.h> is used when it's located in a "system" library folder, i.e. the one where you find all the libraries included with the arduino IDE...