Linker Errors

[SrKiT]

Hi, I'm trying to create a snake game. For that I created some classes (Coordinates, Snake and Board).The classes and their data fields are something like:

 //main.cpp
 #include "Board.h"
 
 int main()

 //Board.h
 #include "Snake.h"
  
 class Board {
 Snake snake;
 Coordinates food;
 std::deque< std::deque<char> > cells;
 };
 //Snake.h
 #include <deque>
 #include "Coordinates.h" 

 class Snake {
 std::deque<Coordinates> body;
 };
 //class Coordinates only has 2 ints, so nothing #included 

I tried to follow http://www.cplusplus.com/forum/articles/10627/ so each .cpp #includes its own header and nothing more and each .h is "guarded" with #ifndef, #define and #endif. Even though I did all that, I'm still getting some linker errors. Can anyone help me doing the right #includes?

[EDIT] I also have other #includes, could that be the problem?
The others are:
iostream
conio.h
cstdlib
time.h

[Peppercorn142]

I'm confused what's going on here O.o...

Maybe this might help?

#include "Board.h"
#include "Snake.h"
#include "Coordinates.h"
#include <deque>

class Board 
{
	Snake snake;
	Coordinates food;
	std::deque<std::deque<char>> cells;
};

class Snake {
std::deque<Coordinates> body;
};

int main()
{
	// Do something here?
	return 0;
}

Also note that class is private by default.
Not completely sure what you're trying to accomplish though.. Sorry ^^

Also on your Header files, at the top try using:

#pragma once 

This will keep the compiler from re-linking the same headers over and over again.

[ne555]

If you could say what errors are you getting, that will be great
Also, look at http://www.cplusplus.com/forum/general/113904/

> each .cpp #includes its own header and nothing more
include what you need.

[SrKiT]

I'm sorry I wasn't clear. What I wrote above isn't the actual whole code, just the really important things. So I actually have the main() defined.
Since the compiler reports linker errors, I assume the cause is somewhere in the #includes. I even though it was because I #included every header file twice (Board.h in Main.cpp and Board.cpp; Snake.h in Board.h and Snake.cpp; Coordinates.h in Snake.h and Coordinates.cpp). But there's no way around that, I think.

[EDIT] The errors are the following:
error LNK2019: unresolved external symbol "public: __thiscall Coordinates::Coordinates(void)" (??0Coordinates@@QAE@XZ) referenced in function "public: __thiscall Board::Board(class Board const &)" (??0Board@@QAE@ABV0@@Z) C:\...\visual studio 2013\Projects\Snake\Snake\Board.obj

error LNK2019: unresolved external symbol "public: __thiscall Snake::Snake(void)" (??0Snake@@QAE@XZ) referenced in function "public: __thiscall Board::Board(class Board const &)" (??0Board@@QAE@ABV0@@Z) C:\...\visual studio 2013\Projects\Snake\Snake\Board.obj

error LNK2019: unresolved external symbol "public: __thiscall Board::Board(void)" (??0Board@@QAE@XZ) referenced in function _main C:\...\visual studio 2013\Projects\Snake\Snake\Source.obj

error LNK1120: 3 unresolved externals C:\...\visual studio 2013\Projects\Snake\Debug\Snake.exe

Now that I think about it, I only declared the default constructors, didn't implement them. Is that it?

[Peppercorn142]

Well the "unresolved externals" means it's not being able to find what you're asking it to find in your code.

So it seems that you've possibly written a function in .cpp file that you thought was in the header file but it isn't..

Example of Error:

// Header File.h
class TestOne
{
private:
public:
    TestOne();
    ~TestOne();

    void myTestFunc();
};

// My CPP File.cpp
#include "Header File.h"
TestOne::TestOne()
{
}
TestOne::~TestOne()
{
}

void myTestFunc() // <--- This it the Error here
{
}

Would change that error line to this..

void TestOne::myTestFunc()
{
}

Reason being, is that myTestFunc is inside the scope of TestOne class.

Do you see something like this inside your code?

[SrKiT]

Yeah, something like that. I called (explicitly) the default constructors which were declared but not defined.
Thank you both.