Forward declaration vs. include header

[linq936]

Hi,
I have a C++ header file like this,

#include "MyClass1.h"

class MyClass2{
private:
MyClass1* c1;
};


In MyClass.h file, there is class declaration of class MyClass1.

But VC7 compiler complains MyClass1 is not a type.

I have to add a forward declaration like this to make compiler
happy,


#include "MyClass1.h"

class MyClass1;

class MyClass2{
private:
MyClass1* c1;
};


I am wondering why is that. "#include" should copy whatever in
MyClass1.h to this header file, and so this header file should have
detailed MyClass1 declararion, right?

 

[Steve Pope]

Hi,
I have a C++ header file like this,

#include "MyClass1.h"

class MyClass2{
private:
MyClass1* c1;
};

In MyClass.h file, there is class declaration of class MyClass1.

But VC7 compiler complains MyClass1 is not a type.

I have to add a forward declaration like this to make compiler
happy,

#include "MyClass1.h"

Are there two files, MyClass.h and MyClass1.h ?

S.

 

[Daniel T.]

Hi,
I have a C++ header file like this,

#include "MyClass1.h"

class MyClass2{
private:
MyClass1* c1;
};


In MyClass.h file, there is class declaration of class MyClass1.

But VC7 compiler complains MyClass1 is not a type.

I have to add a forward declaration like this to make compiler
happy,


#include "MyClass1.h"

class MyClass1;

class MyClass2{
private:
MyClass1* c1;
};

My guess is that something is wrong in the "MyClass1.h" file. Maybe you
got your include guards messed up somehow.

 

[linq936]

My guess is that something is wrong in the "MyClass1.h" file. Maybe you
got your include guards messed up somehow.

I think you are right, the problem is include guards. I clean up the
guards and the problem is gone.

Thanks.