C++. Namespaces and classes

Question

I develop a game with help of PopCap Framework. I found this header in demo:

#ifndef __BOARD_H__
#define __BOARD_H__
#include "SexyAppFramework/Widget.h"
namespace Sexy
{
    class Graphics;
    class GameApp;
    class Board : public Widget
    {
        private:
        GameApp*    mApp;
        public:
        Board(GameApp* theApp);
        virtual ~Board();
        virtual void Draw(Graphics* g);
        virtual void Update();
    };
}
#endif // __BOARD_H__

What does the following mean?

namespace Sexy
{
}

I guess it means the same as

using namespace Sexy;

But for the code within braces, is this so?

And what does it mean?

class Graphics;
class GameApp;

Somebody here needs to grab [a good C++ book](http://stackoverflow.com/q/388242/46642)... — Xeo, Jan 19 '12 at 11:16
`__BOARD_H__` is a reserved identifier, you should remove the leading underscores. — David Rodríguez - dribeas, Jan 19 '12 at 13:03

Irit Katriel · Accepted Answer · 2012-01-19T11:16:01.637

4

namespace X {code}

means that the code in the {} is in namespace X.

using namespace X;

means that the compiler should look up names you use in namespace X.

http://www.cplusplus.com/doc/tutorial/namespaces/

class Graphics;
class GameApp;

are forward declarations

edited Jan 19 '12 at 11:16

answered Jan 19 '12 at 11:10

Irit Katriel

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C++. Namespaces and classes

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