Member function definition outside the class

Question

Firstly, I am giving the codes. Then I am explaining the problem I am facing.

main.cpp

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

using namespace std;
class mem;
int main()
{
    show();
    return 0;
}

acc.h

#ifndef ACC_H
#define ACC_H

#include "acc.cpp"
void show();

class mem{
    int a;
public:
    void showa();
    void seta(int A);
};
#endif

acc.cpp

#include <iostream>
using namespace std;

void mem::showa(){cout<<a<<endl;}
void mem::seta(int A){a = A;}

void show()
{
    mem m;
    m.seta(22);
    string ss;
    cin>>ss;
    cout<<"MY name is "<<ss<<" ";
    m.showa();
}

"mem" class I declared in "acc.h" file already and added that "acc.h" into acc.cpp file also. But when I am calling that class from a function. It can't response. Showing "a" and "mem" not declared. How can I perfectly link that class definition and member functions of that class so that calling member functions of that class from another function can't create any problem?

Answer 1

If you remove the #include "acc.cpp" from the acc.h file it should compile without any errors. I tried and it compiles for me. I am using Visual Studio 2010 for the same.

Other than this, few more comments:

1. You can use #pragma once in you header file instead of #ifndef/#define macros. The former is more cleaner.
2. You dont need to forward declare class mem before main() as you are already including acc.h .
3. the show() can be moved to where main() is defined making the acc.h/acc.cpp files dedicated for the mem class.
4. A header file should always be named after the class it is holding ie mem.h/mem.cpp in your case. This informs which file contains which class even without opening the file.