C++ #include external function issue

I'm a real beginner and I'm programming in C++ us开发者_开发百科ing Visual Studio. I've a simple cpp code that recalls some functions written in a .c and .h file. I included that file by means of #include directive and the IDE "sees" the function. When I compile, I get this

Error 7 error LNK2019: unresolved external symbol _IMUsendAccelToFIFO referenced in function _main D:\Cprojects\Pencil\Pencil\Pencil.obj Pencil

What am I missing here?

Thank you all!

It is a linker error, not a compiler error. The compiler is happy, it saw the declaration of function in the .h file. The linker isn't, it cannot find the definition of the function.

Add the .c file to your project.

If you get an error in Visual Studio you can actually google for the error code and you will get pretty extensive information for that. In this case, googling LNK2019 gives this MSDN page as first hit, which also provides some examples on how you get the error.
Your vendor should have provided some .lib files for you (usually found in a folder named lib?). Make sure that these are added in the project via:

• Project > Properties > Configuration Properties > Linker > Input > Additional Dependencies

You could also see if there is any "get started" information for you from your vendor, which explains which dependencies you have to include in your project.
If you feel unsure of what a compiler and what a linker does, pick up a book that explains it, or browse some free alternatives.

Are you using ghettopilot? that's the only reference I can find on the web to the function you're missing. If you are, then you need to include the .lib file for that library in your link options.

Visual Studio will compile .c files as C and .cpp files as C++ by default, and this can cause trouble because if you want to call functions defined in a .c file from a .cpp file, then you must wrap the header in extern "C" { }, as the compiler will expect all functions not declared extern "C" to be from C++. This is because of an implementation detail called name mangling. Alternatively, you could force all files to be compiled as C or as C++ in the project settings.

Solved! Thank you very much! The libraries I was using needed to be built. I tried but I couldn't build them as I used to get "heap space" error!

I installed Visual Studio 2005 (with which the code was produced by the vendor) and it worked at first attempt! There are probably some back-compatibility issues..