Question

I’m getting

error LNK2005: "bool __cdecl hasLogin(void)" (?hasLogin@@YA_NXZ) already defined in B.obj

error. func is declared in B.cpp file, and it’s called from A.cpp file. B.cpp is included in A.cpp. Google says that it’s not good to include cpp in antother cpp. If I copy/paste func in A.cpp there’s no problem. How to solve tsis problem correctly?

PS I’m new to c++, so forgive if the question is dump.

Answer 1

You should generally declare your classes/functions in .h (header) files, and implement them in .cpp files. It’s also usually a good idea to put include guards in your .h files so including them multiple times is not a problem. That way your .cpp files can include any .h file without causing any conflicts.

An example; test.h

#ifndef TEST_H
#define TEST_H

class test {
    public:
        void bop();
}

bool hasLogin();

#endif

and the corresponding .cpp file

#include <iostream>
#include "test.h"

void test::bop() {
    std::cout << "bop" << std::endl;
}

bool hasLogin() {
    return false;
}