Visual C++ LNK2005 problem

[kfk]

Hi, I need your expert's help on this issue:

1>------ Build started: Project: class_test, Configuration: Release Win32 ------
1>Build started 08-02-2015 18:58:34.
1>InitializeBuildStatus:
1> Creating "Release\class_test.unsuccessfulbuild" because "AlwaysCreate" was specified.
1>ClCompile:
1> stdafx.cpp
1> class_test.cpp

1>stdafx.obj : error LNK2005:
"private: void __thiscall ac::pf(unsigned char *)" (?pf@ac@@AAEXPAE@Z) already defined in class_test.obj

1>C:\Users\Kenneth\documents\visual studio 2010\Projects\class_test\Release\class_test.exe :
fatal error LNK1169: one or more multiply defined symbols found

1>
1>Build FAILED.
1>
1>Time Elapsed 00:00:00.70
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Code compiles just fine. No issues here. When building, linker complains about this call to "pf(&a)"

#pragma once
//
typedef unsigned char byte;

// ac = abstract class
class ac{
public:
// pvf = pure_virtual_func
virtual void pvf() = 0;
virtual void vf1() = 0;
virtual void vf2(){
//
a = 10;
pf(&a); // <-this function call causes linker to complain as shown above
printf("%d", a);
};
private:
byte a;
void pf(byte *);
};


// I want to use scope resolution, so I can define "pf" outside the "ac" class body
// this goes for "vf2" as well all though this function is defined within the "ac" class body
// this was done to show what links without complains and what makes the linker complain
//
void ac::pf(byte *p){
//
a++;
}

// CLASS_TEST.CPP

#include "stdafx.h"


int _tmain(int argc, _TCHAR* argv[])
{
//
dc2 a;
a.vf2();
getchar();
return 0;
}

It seems that functions declared within the "ac" class body can't easily be defined outside the class body. I want
to design the "ac" class this way or like something similar, and not within the class body itself.
How do I do this if possible. Looking forward to some in-depth knowledge here.

Thank you,

Kenneth

[Disch]

I assume the body for ac::pf is in a header? If so, then you have to mark it as inline:

inline void ac::pf(byte *p){  // <- make it inline
  //
  a++;
}

Also... this is unrelated to your question... but...

// ac = abstract class
class ac{
public:
// pvf = pure_virtual_func
virtual void pvf() = 0;

This is a very bad habit. Rather than giving something an extremely vague name like 'ac' and adding comments to explain what 'ac' means... you should just give it a meaningful name:

class Abstract  // <- no comment necessary
{
public:
    virtual void pureVirtual() = 0;  // <- no comment necessary 

This makes your code infinitely easier to read and understand.