Question

When I run a Java Program on Eclipse, each time I run a file, Compiler will check does it has main, if it has, I can run. And if not, I cannot.

But when I run a C++ Program (CDT) on Eclipse using MinGW, at Compiler doesn’t work like that. After I compile, don’t matter I run from which file, Compiler will search whole project to find ONE MAIN So, if I has many main file, I will receive error.

Please tell me in Eclipse, how to treat C++ Compiler to have multi main file and work like on Java: it just find main on which file I run from.

@: I have multi main file just for debugging purpose. !!!

Thanks 🙂

Answer 1

unlike java in a C/C++ you can only have one main:

The main() function is special; normally every C and C++ program must
define it exactly once.

^{( source )}

But: As a workaround you can use preprocessor to decide which of your main‘s you want to use.

Example:

#ifdef FIRST_MAIN
int main(int argc, char** argv)
{
    printf("first");

    return (EXIT_SUCCESS);
}
#elif SECOND_MAIN
int main(int argc, char** argv)
{
    printf("second");

    return (EXIT_SUCCESS);
}
#else
int main(int argc, char** argv)
{
    printf("default");

    return (EXIT_SUCCESS);
}
#endif

Now you can decide wich one you want to use by setting proper flag at compiletime. If none is set you’ll use the default one (#else part).

Alternative: Exclude all your files containing a main-function from compilation and include only the one you need. However, this will only work if those files dont contain more than the main.