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Hello,
I'm trying to compile a programme which compiles fine under Linux; I'm
trying it with MinGW G++ 3.4.2:


Component.h:

#ifndef COMPONENT_H_
#define COMPONENT_H_

#include "../basics/Rectangle.h"

class Component {
private:
Rectangle *bounds;
// Unique identifier
long id;

// more declarations

};

#endif


Rectangle.h (relative path is as included above):

#ifndef RECTANGLE_H_
#define RECTANGLE_H_

#include "Point.h"

class Rectangle
{
// some declarations
};

#endif


Point.h (same directory as Rectangle.h)

#ifndef POINT_H_
#define POINT_H_

class Point {
// some declarations
};

#endif


Now, in Windows, I always get the following compilation errors (where
line 25 in Component.h matches the line "Rectangle *bounds;" shown
above):

In file included from visdgetsbase.h:13,
from main.cpp:14:
widgets/Component.h:25: error: ISO C++ forbids declaration of
`Rectangle' with n
o type
widgets/Component.h:25: error: expected `;' before '*' token
widgets/Component.h:41: error: ISO C++ forbids declaration of
`Rectangle' with n
o type
widgets/Component.h:41: error: expected `;' before '*' token
widgets/Component.h:43: error: variable or field `setBounds' declared
void
widgets/Component.h:43: error: expected `;' before '(' token

So, why isn't Rectangle recognized as a type?

I tried removing the relative path in #include, but that only results
in an additional error message saying that the file Rectangle.h wasn't
found at all. I also made sure I don't have any other file called
Rectangle.h on my entire hard disk, so quite obviously, with the
relative paths given in the #include directive, the correct file
should've been found, then why isn't the type Rectangle?

Thanks in advance,
Florian

On Jan 24, 1:35 pm, "Florian Haag" <florianh...@yahoo.de> wrote:
> Hello,
> I'm trying to compile a programme which compiles fine under Linux; I'm
> trying it with MinGW G++ 3.4.2:
>
> Component.h:
>
> #ifndef COMPONENT_H_
> #define COMPONENT_H_
>
> #include "../basics/Rectangle.h"
>
> class Component {
> private:
> Rectangle *bounds;
> // Unique identifier
> long id;
>
> // more declarations
>
> };
> #endif


> In file included from visdgetsbase.h:13,
> from main.cpp:14:
> widgets/Component.h:25: error: ISO C++ forbids declaration of
> `Rectangle' with no type

Seems to me like the problem might be on line 25 in Component.h (or a
bit above), but the part from Component.h you pasted does not contain
the 25th line so I can't help you. Make sure that the last statement
above line 25 has a ; at the end.

--
Erik Wikström

Erik Wikström wrote:

> Seems to me like the problem might be on line 25 in Component.h (or a
> bit above), but the part from Component.h you pasted does not contain
> the 25th line so I can't help you. Make sure that the last statement
> above line 25 has a ; at the end.

Hi,
sorry if I explained this in a confusing way, actually, the line

Rectangle *bounds;

_is_ line 25, already shown in my code in the original posting (I
removed some comments when copying the code here).

Regards, thanks in advance,
Florian

Florian Haag wrote:

> Erik Wikström wrote:
>
>> Seems to me like the problem might be on line 25 in Component.h (or a
>> bit above), but the part from Component.h you pasted does not contain
>> the 25th line so I can't help you. Make sure that the last statement
>> above line 25 has a ; at the end.
>
> Hi,
> sorry if I explained this in a confusing way, actually, the line
>
> Rectangle *bounds;
>
> _is_ line 25, already shown in my code in the original posting (I
> removed some comments when copying the code here).

Well, in removing that code, you probably removed the error. Post those
lines. (This is covered in the FAQ:

http://www.parashift.com/c++-faq-lit...t.html#faq-5.8


Best

Kai-Uwe Bux

Kai-Uwe Bux wrote:

> Well, in removing that code, you probably removed the error. Post
> those lines. (This is covered in the FAQ:
>
> http://www.parashift.com/c++-faq-lit...t.html#faq-5.8

Sorry, this sent me to the right direction; there was a naming conflict
with a Rectangle-function from wingdi.h, which of course only occurred
in Windows.
I'm sorry for not having followed those rules, I still am not used that
in C++, there can be such an influence accross several files, unlike in
some other languages.

Regards,
Florian

Florian Haag wrote:
> Kai-Uwe Bux wrote:
>
>> Well, in removing that code, you probably removed the error. Post
>> those lines. (This is covered in the FAQ:
>>
>> http://www.parashift.com/c++-faq-lit...t.html#faq-5.8
>
> Sorry, this sent me to the right direction; there was a naming
> conflict with a Rectangle-function from wingdi.h, which of course
> only occurred in Windows.
> I'm sorry for not having followed those rules, I still am not used
> that in C++, there can be such an influence accross several files,
> unlike in some other languages.
>

So C++ provides namespaces to isolate different components into their own
space.


Bo Persson

On Jan 24, 6:24 am, "Florian Haag" <florianh...@yahoo.de> wrote:
> Kai-Uwe Bux wrote:
> > Well, in removing that code, you probably removed the error. Post
> > those lines. (This is covered in the FAQ:
>
> > http://www.parashift.com/c++-faq-lit...l#faq-5.8Sorry, this sent me to the right direction; there was a naming conflict
> with a Rectangle-function from wingdi.h, which of course only occurred
> in Windows.
> I'm sorry for not having followed those rules, I still am not used that
> in C++, there can be such an influence accross several files, unlike in
> some other languages.

Other languages usually solve this "problem" with namespaces. It is
rare that a language allows the same symbol to be used to mean
different things.

Noah Roberts wrote:

> > I'm sorry for not having followed those rules, I still am not used
> > that in C++, there can be such an influence accross several files,
> > unlike in some other languages.
>
> Other languages usually solve this "problem" with namespaces. It is
> rare that a language allows the same symbol to be used to mean
> different things.

Right, well - e.g. in Delphi, if you include another source file A, by
default, you just include the declarations from that very source file
A, not those of other source files B and C referenced by A.

Regards,
Florian