class namespace1::namespace2::class1;

[v4vijayakumar]

Why following statement is not a "forward declaration"?

class namespace1::namespace2::class1;

 

[John Harrison]

Why following statement is not a "forward declaration"?

class namespace1::namespace2::class1;

Who knows? Try

namespace namespace1 { namespace namespace2 { class class1; } }

instead.

john

 

[Sarath]

Why following statement is not a "forward declaration"?

class namespace1::namespace2::class1;

Hmmm... hard to guess...

In your case, I fear the compiler could not resolve the namespace as
you are not including the file (probably the .h file) which has
defined the namespace. That's why the compiler shows error. AFAIK,
namespace can't be forward declared. If the namespace declaration
available, your code will be perfectly valid.

Regards,
Sarath
http://sarathc.wordpress.com/

 

[John Harrison]

If the namespace declaration

available, your code will be perfectly valid.

namespace x
{
namespace y
{
}
}

class x::y::c;

Errors

error C2039: 'c' : is not a member of 'x::y'
error C2365: 'x' : redefinition; previous definition was 'namespace'
error C2079: 'c' uses undefined class 'x'

john

 

[Sarath]

If the namespace declaration


namespace x
{
namespace y
{
}

}

class x::y::c;

Errors

error C2039: 'c' : is not a member of 'x::y'
error C2365: 'x' : redefinition; previous definition was 'namespace'
error C2079: 'c' uses undefined class 'x'

john

In my Visual C++ 6.0 and 7.1 compiler the above statement is perfectly
valid. I'm not sure about other compilers.

Regards,
Sarath
http://sarathc.wordpress.com/

 

[Sarath]

If the namespace declaration


namespace x
{
namespace y
{
}

}

class x::y::c;

Errors

error C2039: 'c' : is not a member of 'x::y'
error C2365: 'x' : redefinition; previous definition was 'namespace'
error C2079: 'c' uses undefined class 'x'

john

Ooops forgot the post the sample code


namespace x
{
namespace y
{

class CTest
{

};
}
}

class x::y::CTest;

This is it

 

[Ian Collins]

Ooops forgot the post the sample code


namespace x
{
namespace y
{

class CTest
{

};
}
}

class x::y::CTest;

This is it

This isn't a forward declaration, John's was.

 

[Sarath]

This isn't a forward declaration, John's was.

I was talking about the validity of the statement. Sorry if poorly
communicated.

 

[Ian Collins]

I was talking about the validity of the statement. Sorry if poorly
communicated.

I see, but the topic was forward declarations, for which the syntax
isn't valid. One has to use the containing namespace as shown in John's
original post.

Please don't quote signatures.