Multiple function definitions

[ntran]

Hi everyone,

I have a cpp file with my main function. At some point it calls for functions which I have declared in another cpp file. Example:

main.cpp

#include<iostream>
#include"functions.cpp"

using namespace std;

int main(){
    cout << "Hello world" << endl;
    function_call();
    return 0;
}

functions.cpp

#include<iostream>

using namespace std;

void function_call(){
    cout << "Bye bye world" << endl;
    return;
}

As I try to compile the project, I get this error message:

multiple definition of 'function_call()'

If I copy the function_call function and paste it over my main function, and delete the functions.cpp file, it works fine. Can someone tell me whats wrong?

[keskiverto]

Sources are compiled; headers included -- with guards.

See http://www.cplusplus.com/articles/Gw6AC542/

(That has mainly classes in other files, but same goes for functions: declaration in header, implementation in source.)

[tipaye]

I don't see where you're including functions.h in functions.cpp, also make sure to use include guards.

Can you post your functions.h and your build command line?

[AbstractionAnon]

The problem is line 2 of your main.cpp file.

You're including your functions.cpp file here. The compiler is also picking up and compiling the functions.cpp file, resulting in two copies of function_call() being compiled. Line 2 should include functions.h, not functions.cpp.

[ntran]

keskiverto, thanks for the source material.

tipaye, I do not have a functions.h file, what should I put in it?

AbstractionAnon, so, are you suggesting that the solution is to change the name of functions.cpp to functions.h, and that's it?

Thanks for your answers.

[ne555]

http://www.cplusplus.com/forum/general/140198/

> I do not have a functions.h file, what should I put in it?
function declarations void function_call();

no need for headers guards if you are not defining anything (class/struct, inline or template functions), but they don't hurt you.

[ntran]

Thank you to everyone, I learned something new today.