How to compile a C project with more than one main function?

Question

I am new to C, and now read some textbook and going to apply its examples.

The problem is, whenever I creates a new project and try to put more than one file that contains a main function, the linker (as I thougt0 explains saying:

/home/mohammed/tmp/abcd/main.c:4: multiple definition of `main'

(BTW, I used many IDEs, MonoDevelop, QT creator, VS2010, Codebloks, ...) I am currently uses QT Creator, It seems to be a very nice IDE.

So, there's not a workaround to solve such problem??

EDIT:

I am asking because I am in the learning stage, and not do real programming right now. I just need a simple way to create programs in C without have to create a separate project per book example. At the same time, I don't want to use Gedit/VI + commandline.

So, Isn't there any way such as cleaning the project, then compile the - just - one file that I need to run ??? BTW, In JAVA we can run a program that cotains more than one main (the IDE give me the choice among them)

Answer 1

What are you trying to do with the multiple main functions?

If you are trying to compile multiple different programs at once, you need to compile each one separately (i.e. only one main per program).

If you are trying to compile one program and want the multiple main functions all to run, you can't. You need to specify only one main and rename the others to something else (and call them from the single main in the order you want them to run).

If you are trying to use just one of the main functions as the single entry point to your program and ignore the others, then you should not include the files with the other mains when you are linking. I suggest placing each main in a separate file if you wish to keep them, and only include one of these main-files when you link/compile.

If you get this error by mistake, then you are probably doing something wrong with the project in your IDE. Perhaps you are accidentally trying to compile multiple different programs into one? You might need to specify each file containing a main as a separate build product. C is not like Java where you can put a main method inside every class and specify which one to call; the main in C is a global name.