C / C++ / MFC

26-May-12 6:53

I am getting a syntax error on "namespace" declaring the following in MFC class variables. iostream is included in StdAfx header file.

namespace Test
{
int a;
int b;
}

Here is the partial error printout
error C2059: syntax error : 'namespace'
error C2334: unexpected token(s) preceding '{'; skipping apparent function body

Does that mean that in VC 6.0 I cannot use "namespace"?
Or did I missed something else?
Thanks for your time.
Vaclav

jschell26-May-12 7:32

jschell

26-May-12 7:32

Vaclav_Sal wrote:
Does that mean that in VC 6.0 I cannot use "namespace"?

Probably.

Your code, exactly what you posted, compiles in VS 2005.

C^hris L^osinger26-May-12 8:23

26-May-12 8:23

you're missing something else. namespaces work fine in VC6.

Vaclav_26-May-12 14:51

26-May-12 14:51

Addendum:
I build default MFC doc / view app and
I get same error with or without including either iostream or iostream.h.
To me that indictates that iostream does not define namespace.
Can it be defined somewhere else?

C^hris L^osinger26-May-12 17:48

26-May-12 17:48

what do you mean by "define namespace" ?

Vaclav_26-May-12 18:32

26-May-12 18:32

If I get a syntax error the compiler does not recognize the "namespace" as valid syntax.
So it has to be defined to be vaild. Does not?

For example "if" is defined in similar way, but compiler flags "iff" as undeclared identifier.
I am just trying to find some reason why I am getting same syntax error with or without including iostream.

C^hris L^osinger27-May-12 3:02

27-May-12 3:02

'namespace' and 'if' are C++ keywords. they're not defined in headers anywhere, they're built into the compiler itself.

Aescleal26-May-12 20:53

Aescleal

26-May-12 20:53

You've probably left a semicolon, closing brace, closing parentheses or similar off the previous thing in the .h file.

Just out of interest, if you ever want to know if you can use a feature in a compiler just lop the code out and stick it in a .cpp file somewhere, making sure it's not dependent on any other code. In this case had you stuck:

C++

namespace Test
{
    int a;
    int b;
}

in a source file you'd have seen it compiles just fine in VC++6.0. As far as anything can be regarded as "compiling just fine" on that clunky piece of old rubbish.

Vaclav_26-May-12 23:50

26-May-12 23:50

Hello Ash,
here is a snippet of VC 6.0 generated CView header file with my add and resulting compliler errors:

class CTESTView : public CView
{
protected: // create from serialization only
CTESTView();
DECLARE_DYNCREATE(CTESTView)
// Attributes
public:
CTESTDoc* GetDocument();
using namespace test
{
int a;
int b;
}

// Operations
public:
.........

This is how iostram is included in STdAfx.h file:

#if !defined(AFX_STDAFX_H__D78D5AFB_F290_4B69_9F5A_23EC3FA245D9__INCLUDED_)
#define AFX_STDAFX_H__D78D5AFB_F290_4B69_9F5A_23EC3FA245D9__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
#include <iostream> <b>silly but the CodeProject edit box did not copy stuff in "arrow brackets" - but it is here - iostream

It did not show up in preview, go figure.

</b>
#define VC_EXTRALEAN // Exclude rarely-used stuff from Windows headers
.....

And here is the full compiler output regardless of inclusion of iostream or not:

--------------------Configuration: TEST - Win32 Debug--------------------
Compiling...
TEST.cpp
z:\0\0 mdi\test\bamesapce\test\testview.h(23) : error C2059: syntax error : 'namespace'
z:\0\0 mdi\test\bamesapce\test\testview.h(24) : error C2334: unexpected token(s) preceding '{'; skipping apparent function body
TESTView.cpp
z:\0\0 mdi\test\bamesapce\test\testview.h(23) : error C2059: syntax error : 'namespace'
z:\0\0 mdi\test\bamesapce\test\testview.h(24) : error C2334: unexpected token(s) preceding '{'; skipping apparent function body
Generating Code...
Error executing cl.exe.
TEST.exe - 4 error(s), 0 warning(s)

I am ready to stop trying this, I really do not need it, but the stuff I am modyfying is using it. After succes of using
pure virtual class / function ( BTW many thanks for all you input on that ) I am just "looking for punishment".

Is it possible that I have some kinda of conflict with std namespace?

C^hris L^osinger27-May-12 2:57

27-May-12 2:57

using namespace test
     {
          int a;
          int b;
     }

that's the problem.

it should be:

namespace test
{
     int a;
     int b;
}; // need the semcolon, too

and then, in your .cpp:

using namespace test;

<--- fixed

Vaclav_27-May-12 4:53

27-May-12 4:53

Thanks Chris,
and this is the compiler output after your suggestion:

TEST.cpp
z:\0\0 mdi\test\bamesapce\test\testview.h(23) : error C2059: syntax error : 'namespace'
z:\0\0 mdi\test\bamesapce\test\testview.h(24) : error C2334: unexpected token(s) preceding '{'; skipping apparent function body
TESTDoc.cpp
TESTView.cpp
z:\0\0 mdi\test\bamesapce\test\testview.h(23) : error C2059: syntax error : 'namespace'
z:\0\0 mdi\test\bamesapce\test\testview.h(24) : error C2334: unexpected token(s) preceding '{'; skipping apparent function body
Z:\0\0 MDI\TEST\BAMESAPCE\TEST\TESTView.cpp(60) : error C2873: 'test' : symbol cannot be used in a using-declaration
Generating Code...
Error executing cl.exe.
TEST.exe - 5 error(s), 0 warning(s)

And here is what my ancient MSDN say about namespace:

namespace Declaration
C++ Specific —>
namespace [identifier] { namespace-body }
A namespace declaration identifies and assigns a name to a declarative region.
The identifier in a namespace declaration must be unique in the declarative region in which it is used. The identifier is the name of the namespace and is used to reference its members.
The declarative region of a namespace declaration is its namespace-body.
END C++ Specific

Notice - no semicolon.

And if it is a keyword it must not be in my VC6.0 Sp6 stuff.

I give up.

C^hris L^osinger27-May-12 5:00

27-May-12 5:00

here is the complete source of a test program demonstrating the use of namespaces in VC6:

C++

namespace foo
{
	class testing
	{
	public:
		testing()
		{
			i = 10;
		}

		int i;
	};
};

using namespace foo;

int main(int argc, char* argv[])
{
   testing t();
   return 0;
}

Aescleal28-May-12 5:32

Aescleal

28-May-12 5:32

Hi Chris - your line:

C++

testing t();

doesn't actually create a new object. It's a prototype for a function that takes no parameters and returns a testing object.

It's a real bugger with C++ and bites loads of people. It's also the reason that the latest C++ standard introduced uniform initialisation (using braces where we've used parenthesis up to now).

C^hris L^osinger28-May-12 5:54

28-May-12 5:54

ok. but that's not the point here.

Aescleal28-May-12 5:29

Aescleal

28-May-12 5:29

Ah ha! Your problem is nesting a namespace within a class. You can't do that. This code gives the same error you got:

C++

class A
{
    namespace B
    {
    }
};

If you want something similar to a namespace nested within a class use another class:

C++

class A
{
    class B
    {
    };
};

It's probably got the effect you want.

Vaclav_28-May-12 7:22