RE: extern C and static data type problem with g++

RE: extern C and static data type problem with g++

[Lev Assinovsky]

Hi Luu!
enum in C&C++ is something like #define in the sence 
of memory allocating. Nothing is allocated for #define and for enum as well.
The difference is #define is resolved in preprocessor time, when 
enum tokens follow the scope rules (class, namespace) and do exist 
at compile time.
Sorry for my English :( 

----
Lev Assinovsky
Aelita Software Corporation 
(now is a part of Quest Software)
O&S InTrust Framework Division, Team Leader
ICQ# 165072909


> -----Original Message-----
> From: Luu Vo [mailto:vtluu@tma.com.vn]
> Sent: Tuesday, April 27, 2004 1:14 PM
> To: gcc-help@gcc.gnu.org
> Subject: extern C and static data type problem with g++
> 
> 
> In RH Linux 9, when compiling my C++ program with lines as below:
> 
> extern "C" struct {int x};
> static enum E{A=0, B, C};
> 
> g++ said:
> 
> storage class specified for field `x'
> `static' can only be specified for objects and functions
> 
> Is this just the implementation of g++? That means I can't 
> use static and
> extern "C" for those lines of code?
> 
> Another question: with GNU g++/gcc compiler and its C++ 
> library, can I use
> both traditional C++ lib (e.g., classic iostream) and standard C++ lib
> (e.g., standard iostream) in my C++ program. Are the both libraries
> implemented in glibstdc++?
> 
> Any help will be appreciated.
> 
> Luu Vo.
> 
> 

Re: extern C and static data type problem with g++

[llewelly]

"Luu Vo" <vtluu@tma.com.vn> writes:

> In RH Linux 9, when compiling my C++ program with lines as below:
> 
> extern "C" struct {int x};
> static enum E{A=0, B, C};

extern "C"
{
  struct x {int x;};
  enum e{a= 0, b, c};
}

> 
> g++ said:
> 
> storage class specified for field `x'

Maybe the gcc 3.4 diagnostic is better:
extrn.cc:3: error: ISO C++ prohibits anonymous structs

> `static' can only be specified for objects and functions
> 
> Is this just the implementation of g++?

It is required by the ISO C++ standard. 

> That means I can't use static and
> extern "C" for those lines of code?
> 
> Another question: with GNU g++/gcc compiler and its C++ library, can I use
> both traditional C++ lib (e.g., classic iostream) and standard C++ lib
> (e.g., standard iostream) in my C++ program.

Any code which uses classic iostreams should be updated to use standard
    iostreams. 

GCC >= 3.0 does not support classic iostreams. "iostream.h" is just:

#include "backward_warning.h"
#include <iostream>

and some appropriate using declarations. For simple cases this is
    backward-compatible with classic iostreams, but in some cases it
    is not.

So if you tried to use 'both' you would really be using the same
    iostreams in both places.


> Are the both libraries
> implemented in glibstdc++?

No.

extern C and static data type problem with g++

[Luu Vo]

In RH Linux 9, when compiling my C++ program with lines as below:

extern "C" struct {int x};
static enum E{A=0, B, C};

g++ said:

storage class specified for field `x'
`static' can only be specified for objects and functions

Is this just the implementation of g++? That means I can't use static and
extern "C" for those lines of code?

Another question: with GNU g++/gcc compiler and its C++ library, can I use
both traditional C++ lib (e.g., classic iostream) and standard C++ lib
(e.g., standard iostream) in my C++ program. Are the both libraries
implemented in glibstdc++?

Any help will be appreciated.

Luu Vo.