function already defined in .obj

Question

From what I understand, this error is caused by not properly using header guards when you have multiple files including the same file. In my case, this is the include tree that

Answer 1

It seems you are trying to define a variable in a header file. If that header file is included in several source file it will be define in each source file thereby giving you the error.

Instead declare it as extern and then define in one of your source files.

So in the header file:

extern ObjectType Object;

And in a source file:

ObjectType Object;