Programming Forums > Application Development > C++

titaniumdecoy · Jun 30th, 2008, 2:25 AM

I am trying to write a chess game in C++ to get a better understanding of the language. I am getting an error that I cannot figure out:

(Toggle Plain Text)

Piece.h:11: error: ISO C++ forbids declaration of ‘Board’ with no type
Piece.h:11: error: expected ‘;’ before ‘*’ token
make: *** [Chess.o] Error 1

Piece.h:

 C++ Syntax (Toggle Plain Text) 
#ifndef PIECE_H
#define PIECE_H
 
#include "Board.h"
 
namespace ChessGame {
 
class Piece
{
  protected:
    Board *board; // this line is indicated in the error message
 
...
#ifndef PIECE_H
#define PIECE_H

#include "Board.h"

namespace ChessGame {

class Piece
{
  protected:
    Board *board; // this line is indicated in the error message

...

Board.h:

 C++ Syntax (Toggle Plain Text) 
#ifndef BOARD_H
#define BOARD_H
 
#include <iostream>
#include "Piece.h"
 
namespace ChessGame {
 
class Board
{
  private:
    Piece *pieces[8][8];
 
...
#ifndef BOARD_H
#define BOARD_H

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

namespace ChessGame {

class Board
{
  private:
    Piece *pieces[8][8];

...

My guess is that the problem is caused by both files including each other.

titaniumdecoy · Jun 30th, 2008, 2:42 AM

I figured it out. I had to add a "forward declaration" for the other class at the beginning of each header file.

Klarre · Jun 30th, 2008, 6:16 AM

Great you solved it! What you got is called "Circular dependency".

titaniumdecoy · Jun 30th, 2008, 7:58 PM

I have another problem. I have a pure virtual class Piece from which Pawn is derived. The Piece class contains a pointer to a Board object. When I define the virtual destructor for the class, I get this error:

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g++ -c -Wall Piece.c
Piece.c: In destructor ‘virtual ChessGame::Piece::~Piece()’:
Piece.c:17: warning: possible problem detected in invocation of delete operator:
Piece.c:17: warning: invalid use of undefined type ‘struct ChessGame::Board’
Piece.h:8: warning: forward declaration of ‘struct ChessGame::Board’
Piece.c:17: note: neither the destructor nor the class-specific operator delete will be called, even if they are declared when the class is defined.
g++ -c -Wall Pawn.c
g++ -o chess -Wall Chess.o Board.o Piece.o Pawn.o

Is this message displayed because the class is abstract? Please advise.

EDIT: Never mind. It turns out I had to #include "Board.h" in order to delete a Board object.

titaniumdecoy · Jun 30th, 2008, 9:46 PM

Ok, another problem. I am trying to print a Piece (specifically a Pawn) to std::cout. In main(), I have no problem printing a pawn:

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Pawn pawn(board);
std::cout << pawn << std::endl;

I have a 2D array of pointers to objects derived from the pure virtual class Pieces in class Board. I am trying to print a piece as follows (Note that I have made Board.pieces temporarily public while I test this):

(Toggle Plain Text)

inline std::ostream& operator<< (std::ostream& os, const Board& board) 
{
    int i = 0, j = 0;
    ...
    if (board.pieces[i][j] != NULL)
        std::cout << *(board.pieces[i][j]) << " ";
    ...
    return os;
}

I get a huge unreadable printout, the beginning of which I have copied below:

(Toggle Plain Text)

Board.h: In function ‘std::ostream& ChessGame::operator<<(std::ostream&, const ChessGame::Board&)’:
Board.h:33: error: no match for ‘operator<<’ in ‘std::cout << *(ChessGame::Piece*)board->ChessGame::Board::pieces[i][j]’
/usr/include/c++/4.0.0/bits/ostream.tcc:67: note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& (*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>]

...

Board.h:26: note:                 std::ostream& ChessGame::operator<<(std::ostream&, const ChessGame::Board&)
make: *** [Piece.o] Error 1

Help!

Jessehk · Jun 30th, 2008, 10:10 PM

It looks like you need to get rid of the pointer dereference (the *) when you access the specific piece on the board.

titaniumdecoy · Jun 30th, 2008, 10:16 PM

When I do that, it just prints the address of the pointer...

titaniumdecoy · Jun 30th, 2008, 10:44 PM

Ok, so far I have been unable to solve the printing problem, but I have an even more annoying problem now:

(Toggle Plain Text)

Pawn.h:11: error: expected class-name before ‘{’ token
Pawn.h:13: error: expected `)' before ‘&’ token
make: *** [Piece.o] Error 1

Pawn.h:

 C++ Syntax (Toggle Plain Text) 
#ifndef PAWN_H
#define PAWN_H
 
#include <iostream>
#include "Piece.h"
#include "Board.h"
 
namespace ChessGame {
 
class Pawn : public Piece
{ // line 11
  public:
    Pawn(Board& board); // line 13
 
...
#ifndef PAWN_H
#define PAWN_H

#include <iostream>
#include "Piece.h"
#include "Board.h"

namespace ChessGame {

class Pawn : public Piece
{ // line 11
  public:
    Pawn(Board& board); // line 13

...

Help!

titaniumdecoy · Jul 1st, 2008, 12:26 AM

I solved the problem in the post above. It turns out that I moved the definition,
std::ostream& operator<< (std::ostream& os, const ChessGame::Board& board) {
From Board.h to Board.c, a change which the compiler did not approve of.

I also had to remove a number of #include "xxx.h" in favor of forward class declarations.

As for the problem printing a Pawn to std::cout, I am still stumped.
EDIT: I finally figured it out. I had to #include "Piece.h" in Board.h.

Jun 30th, 2008, 2:25 AM	#1
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Declaration of ‘Class’ with no type I am trying to write a chess game in C++ to get a better understanding of the language. I am getting an error that I cannot figure out: (Toggle Plain Text) Piece.h:11: error: ISO C++ forbids declaration of ‘Board’ with no type Piece.h:11: error: expected ‘;’ before ‘’ token make: ** [Chess.o] Error 1 Piece.h:11: error: ISO C++ forbids declaration of ‘Board’ with no type Piece.h:11: error: expected ‘;’ before ‘’ token make: [Chess.o] Error 1 Piece.h: C++ Syntax** (Toggle Plain Text) #ifndef PIECE_H #define PIECE_H #include "Board.h" namespace ChessGame { class Piece { protected: Board board; // this line is indicated in the error message ... #ifndef PIECE_H #define PIECE_H #include "Board.h" namespace ChessGame { class Piece { protected: Board board; // this line is indicated in the error message ... Board.h: C++ Syntax (Toggle Plain Text) #ifndef BOARD_H #define BOARD_H #include <iostream> #include "Piece.h" namespace ChessGame { class Board { private: Piece pieces[8][8]; ... #ifndef BOARD_H #define BOARD_H #include <iostream> #include "Piece.h" namespace ChessGame { class Board { private: Piece pieces[8][8]; ... My guess is that the problem is caused by both files including each other. Last edited by titaniumdecoy; Jun 30th, 2008 at 2:53 AM.

Jun 30th, 2008, 2:42 AM	#2
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Re: Declaration of ‘Class’ with no type I figured it out. I had to add a "forward declaration" for the other class at the beginning of each header file.

Jun 30th, 2008, 6:16 AM	#3
Klarre Game engine designer Join Date: May 2005 Location: Sweden Posts: 301 Rep Power: 4	Re: Declaration of ‘Class’ with no type Great you solved it! What you got is called "Circular dependency". __________________ http://www.klarre.se

Jun 30th, 2008, 7:58 PM	#4
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Re: Declaration of ‘Class’ with no type I have another problem. I have a pure virtual class Piece from which Pawn is derived. The Piece class contains a pointer to a Board object. When I define the virtual destructor for the class, I get this error: (Toggle Plain Text) g++ -c -Wall Piece.c Piece.c: In destructor ‘virtual ChessGame::Piece::~Piece()’: Piece.c:17: warning: possible problem detected in invocation of delete operator: Piece.c:17: warning: invalid use of undefined type ‘struct ChessGame::Board’ Piece.h:8: warning: forward declaration of ‘struct ChessGame::Board’ Piece.c:17: note: neither the destructor nor the class-specific operator delete will be called, even if they are declared when the class is defined. g++ -c -Wall Pawn.c g++ -o chess -Wall Chess.o Board.o Piece.o Pawn.o g++ -c -Wall Piece.c Piece.c: In destructor ‘virtual ChessGame::Piece::~Piece()’: Piece.c:17: warning: possible problem detected in invocation of delete operator: Piece.c:17: warning: invalid use of undefined type ‘struct ChessGame::Board’ Piece.h:8: warning: forward declaration of ‘struct ChessGame::Board’ Piece.c:17: note: neither the destructor nor the class-specific operator delete will be called, even if they are declared when the class is defined. g++ -c -Wall Pawn.c g++ -o chess -Wall Chess.o Board.o Piece.o Pawn.o Is this message displayed because the class is abstract? Please advise. EDIT: Never mind. It turns out I had to #include "Board.h" in order to delete a Board object.

Jun 30th, 2008, 9:46 PM	#5
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Re: Declaration of ‘Class’ with no type Ok, another problem. I am trying to print a Piece (specifically a Pawn) to std::cout. In main(), I have no problem printing a pawn: (Toggle Plain Text) Pawn pawn(board); std::cout << pawn << std::endl; Pawn pawn(board); std::cout << pawn << std::endl; I have a 2D array of pointers to objects derived from the pure virtual class Pieces in class Board. I am trying to print a piece as follows (Note that I have made Board.pieces temporarily public while I test this): (Toggle Plain Text) inline std::ostream& operator<< (std::ostream& os, const Board& board) { int i = 0, j = 0; ... if (board.pieces[i][j] != NULL) std::cout << (board.pieces[i][j]) << " "; ... return os; } inline std::ostream& operator<< (std::ostream& os, const Board& board) { int i = 0, j = 0; ... if (board.pieces[i][j] != NULL) std::cout << (board.pieces[i][j]) << " "; ... return os; } I get a huge unreadable printout, the beginning of which I have copied below: (Toggle Plain Text) Board.h: In function ‘std::ostream& ChessGame::operator<<(std::ostream&, const ChessGame::Board&)’: Board.h:33: error: no match for ‘operator<<’ in ‘std::cout << (ChessGame::Piece)board->ChessGame::Board::pieces[i][j]’ /usr/include/c++/4.0.0/bits/ostream.tcc:67: note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& ()(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>] ... Board.h:26: note: std::ostream& ChessGame::operator<<(std::ostream&, const ChessGame::Board&) make: ** [Piece.o] Error 1 Board.h: In function ‘std::ostream& ChessGame::operator<<(std::ostream&, const ChessGame::Board&)’: Board.h:33: error: no match for ‘operator<<’ in ‘std::cout << (ChessGame::Piece)board->ChessGame::Board::pieces[i][j]’ /usr/include/c++/4.0.0/bits/ostream.tcc:67: note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& ()(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>] ... Board.h:26: note: std::ostream& ChessGame::operator<<(std::ostream&, const ChessGame::Board&) make: ** [Piece.o] Error 1 Help! Last edited by titaniumdecoy; Jun 30th, 2008 at 9:58 PM.

Jun 30th, 2008, 10:10 PM	#6
Jessehk The Oblivious One Join Date: May 2005 Location: Ontario, Canada Posts: 644 Rep Power: 4	Re: Declaration of ‘Class’ with no type It looks like you need to get rid of the pointer dereference (the *) when you access the specific piece on the board. __________________ Dr. Zoidberg: [ecstatic] I'm going to a movie... with FRIENDS!

Jun 30th, 2008, 10:16 PM	#7
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Re: Declaration of ‘Class’ with no type When I do that, it just prints the address of the pointer...

Jun 30th, 2008, 10:44 PM	#8
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Re: Declaration of ‘Class’ with no type Ok, so far I have been unable to solve the printing problem, but I have an even more annoying problem now: (Toggle Plain Text) Pawn.h:11: error: expected class-name before ‘{’ token Pawn.h:13: error: expected `)' before ‘&’ token make: * [Piece.o] Error 1 Pawn.h:11: error: expected class-name before ‘{’ token Pawn.h:13: error: expected `)' before ‘&’ token make: * [Piece.o] Error 1 Pawn.h: C++ Syntax (Toggle Plain Text) #ifndef PAWN_H #define PAWN_H #include <iostream> #include "Piece.h" #include "Board.h" namespace ChessGame { class Pawn : public Piece { // line 11 public: Pawn(Board& board); // line 13 ... #ifndef PAWN_H #define PAWN_H #include <iostream> #include "Piece.h" #include "Board.h" namespace ChessGame { class Pawn : public Piece { // line 11 public: Pawn(Board& board); // line 13 ... Help!

Jul 1st, 2008, 12:26 AM	#9
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Re: Declaration of ‘Class’ with no type I solved the problem in the post above. It turns out that I moved the definition, `std::ostream& operator<< (std::ostream& os, const ChessGame::Board& board) {` From Board.h to Board.c, a change which the compiler did not approve of. I also had to remove a number of #include "xxx.h" in favor of forward class declarations. As for the problem printing a Pawn to std::cout, I am still stumped. EDIT: I finally figured it out. I had to #include "Piece.h" in Board.h. Last edited by titaniumdecoy; Jul 1st, 2008 at 12:40 AM.

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Programming Forums > Application Development > C++

Declaration of ‘Class’ with no type