class definition position?

[cylin]

Dear all,

For example,

class CA;

class CB {
public:
int m_iY;
CA m_oCA;
};

class CA {
public:
int m_iX;
};

I use BCB compiler, but it says "undefined structure CA".
The style is standard, why it can't compile well?
I know if I put full definition of CA before CB, it's ok.
Thanks for your answer.

Regards,
cylin.

 

[Josephine Schafer]

Dear all,

For example,

class CA;

class CB {
public:
int m_iY;
CA m_oCA;
};

class CA {
public:
int m_iX;
};

I use BCB compiler, but it says "undefined structure CA".
The style is standard, why it can't compile well?

Because the compiler does not know the size of CA.
A forward declarartion only tells the compiler that such a class
exists somewhere but does not tell it's size which is required here.
Else use a pointer/reference to CA in CB.

HTH.

 

[cylin]

Thanks all, I learn much.

Regards,
cylin.