) You solve this by ‘defining the class’ in only one cpp file. Why would you want to define it in two files? 2) Don’t define things in header files, only declare them. There are exceptions to this rule, for instance inline functions. Also classes themselves can defined more than once (by this I mean … Read more
The problem here is that you are including commands.c in commands.h before the function prototype. Therefore, the C pre-processor inserts the content of commands.c into commands.h before the function prototype. commands.c contains the function definition. As a result, the function definition ends up before than the function declaration causing the error. The content of commands.h … Read more
You actually compile the source code of test.c twice: The first time when compiling test.c itself, The second time when compiling main.c which includes all the test.c source. What you need in your main.c in order to use the test() function is a simple declaration, not its definition. This is achieved by including a test.h … Read more