Question

im a noob especially in c++.

I have some problems using a struct that i want to use in some functions.

I looked at the other answers here regarding structs in Header files and .cpp but dont realy get it to work.

my .h file:

namespace game {

class CPlayer{

        struct GameData{
        int mBoard[8][8];
        CBoard &pBoard;
    };
public:

    CMove Play(const CBoard &pBoard,const CDeadline &pDue);

private:

    int GainsFromMoves(struct GameData gameData);

etc…..

then in my .cc file im trying to use this data with:

CMove CPlayer::Play(const CBoard &pBoard,const CDeadline &pDue)
{

     GameData gameData;

     gameData.pBoard = pBoard;

etc…

where i try to declare the GameData i get an error uninitialized reference member in ‘struct game::CPlayer::GameData’

later trying to usethe GainsFromMoves function i also get some error.

int GainsFromMoves(GameData gameData){

 int test = 0;

 return test;
}

error: Multiple markers at this line
    - expected ‘,’ or ‘;’ before ‘{’ token
    - ‘GameData’ was not declared in this 
     scope

i realize that i probably am doing some really noob error but, i would be very happy for some guidance.

Answer 1

OK, first, you need declarations of CMove, CBoard and CDeadline. I added some dummy ones to allow fixing the other problems:

namespace game {

struct CBoard {};
struct CDeadline {};
struct CMove {};
...

Then, your struct CPlayer::GameData needs to intialize it’s CBoard reference, which should be const:

class CPlayer{

        struct GameData
        {
          GameData(const CBoard& board) : pBoard(board) {}
          int mBoard[8][8];
          const CBoard &pBoard;
        };
public:
    CMove Play(const CBoard &pBoard,const CDeadline &pDue);
private:
    int GainsFromMoves(struct GameData gameData);
};

Next, in your .cc file, you need the namespace as well as the class name when defining member functions:

namespace game
{
CMove CPlayer::Play(const CBoard &pBoard,const CDeadline &pDue)
{
     GameData gameData(pBoard);
     return CMove();
}
int CPlayer::GainsFromMoves(GameData gameData){

  int test = 0;

 return test;
}

} // namespace game

This gets rid of the errors, at least with this simple main:

int main()
{
  game::CBoard b;
  game::CDeadline d;
  game::CPlayer p;
  p.Play(b, d);
}