Hi !
I have some strange problem and I would like to know if it is a bug or not :
In my projects, in 2 different .cpp files, I use the same name to define a
local structure:
file1.cpp :
typedef struct TOTO
{
CString s;
GUID g;
GUID g;
};
file2.cpp :
typedef struct TOTO
{
GUID g;
CString s;
};
When I instanciate a variable toto of type TOTO in the file1.cpp, it works
but the content of variable members are strange. And when I try to define
the s variable I have a violent error.
TOTO toto; // ok ! but toto.s contains "U$...." instead of ""
toto.s = "yo"; // violent error !
I am programming in C++ and using Visual .NET 2003. The 2 files have the the
include on the precompiled header file (stdafx.h).
thanks for your help...
Mike 4 1447
On Thu, 30 Nov 2006 11:52:26 +0100, "Mike" <mi*****@nest or-tech.dot.com>
wrote:
>Hi !
I have some strange problem and I would like to know if it is a bug or not :
In my projects, in 2 different .cpp files, I use the same name to define a local structure:
file1.cpp :
typedef struct TOTO {
CString s;
GUID g;
GUID g; };
file2.cpp :
typedef struct TOTO {
GUID g;
CString s; };
To fix the declaration errors, delete the typedefs.
>When I instanciate a variable toto of type TOTO in the file1.cpp, it works but the content of variable members are strange. And when I try to define the s variable I have a violent error.
TOTO toto; // ok ! but toto.s contains "U$...." instead of "" toto.s = "yo"; // violent error !
I am programming in C++ and using Visual .NET 2003. The 2 files have the the include on the precompiled header file (stdafx.h).
This is not a VC bug. You are violating the one definition rule (ODR) by
defining two structs with the same name but different contents in the same
scope, which here is the global namespace. The compiler is not required to
detect this, but you can fix your code by using anonymous namespaces:
file1.cpp :
namespace {
struct TOTO
{
CString s;
GUID g;
GUID g;
};
}
file2.cpp :
namespace {
struct TOTO
{
GUID g;
CString s;
};
}
--
Doug Harrison
Visual C++ MVP
Thanks for your help Doug
I believed I can do this because my structures were not declared in the
header files.
For me this error comes from the linker. The compiler cannot detect this
kind of error because the structures are not declared in the header files.
But I understand that these structures are in the global namespace, thanks
for the tip.
I have a question about this problem : I have many many .cpp files, so I
have to know all the local structures definitions names when I want to
define another one in a .cpp ?
And what happens if I use a library file instead of cpp files. If the lib
has, somewhere, a local structure definition, how can I know the name of
this structure if it is not declared in the headers ? so is it possible to
have the same kind of error ?
So, if I understand, I must always use an anonymous namespace everywhere I
want to define a local structure ?
Mike
"Doug Harrison [MVP]" <ds*@mvps.orgwr ote in message
news:t1******** *************** *********@4ax.c om...
On Thu, 30 Nov 2006 11:52:26 +0100, "Mike" <mi*****@nest or-tech.dot.com>
wrote:
>>Hi !
I have some strange problem and I would like to know if it is a bug or not :
In my projects, in 2 different .cpp files, I use the same name to define a local structure:
file1.cpp :
typedef struct TOTO { CString s; GUID g; GUID g; };
file2.cpp :
typedef struct TOTO { GUID g; CString s; };
To fix the declaration errors, delete the typedefs.
>>When I instanciate a variable toto of type TOTO in the file1.cpp, it works but the content of variable members are strange. And when I try to define the s variable I have a violent error.
TOTO toto; // ok ! but toto.s contains "U$...." instead of "" toto.s = "yo"; // violent error !
I am programming in C++ and using Visual .NET 2003. The 2 files have the the include on the precompiled header file (stdafx.h).
This is not a VC bug. You are violating the one definition rule (ODR) by
defining two structs with the same name but different contents in the same
scope, which here is the global namespace. The compiler is not required to
detect this, but you can fix your code by using anonymous namespaces:
file1.cpp :
namespace {
struct TOTO
{
CString s;
GUID g;
GUID g;
};
}
file2.cpp :
namespace {
struct TOTO
{
GUID g;
CString s;
};
}
--
Doug Harrison
Visual C++ MVP
On Fri, 1 Dec 2006 09:42:30 +0100, "Mike" <mi*****@nest or-tech.dot.com>
wrote:
>Thanks for your help Doug
I believed I can do this
You can, but you'll get the weird results you got. :)
>because my structures were not declared in the header files.
The header/source file distinction is irrelevant. The preprocessor replaces
a #include directive with the indicated file's contents before the compiler
even sees the code. It matters not a bit if a piece of code came from a
#include directive or was part of the #including file.
>For me this error comes from the linker. The compiler cannot detect this kind of error because the structures are not declared in the header files.
The compiler cannot detect the error because the structs are defined in
different translation units, which the compiler compiles separately.
>But I understand that these structures are in the global namespace, thanks for the tip.
I have a question about this problem : I have many many .cpp files, so I have to know all the local structures definitions names when I want to define another one in a .cpp ?
That problem is solved by anonymous namespaces.
>And what happens if I use a library file instead of cpp files. If the lib has, somewhere, a local structure definition, how can I know the name of this structure if it is not declared in the headers ?
In general, you can't, and with anonymous namespaces, you don't have to.
>so is it possible to have the same kind of error ?
Yep.
>So, if I understand, I must always use an anonymous namespace everywhere I want to define a local structure ?
Yep. This was a real problem before namespaces were added to the language.
While "static" worked for global functions and data, it couldn't be applied
to classes, which have linkage due to member functions (including
compiler-generated ones relevant to your example, i.e. ctors, dtors, and
assignment operator), static members, vtbls, etc.
--
Doug Harrison
Visual C++ MVP
thanks a lot for your help Doug, I will apply your advices...
"Doug Harrison [MVP]" <ds*@mvps.orgwr ote in message
news:to******** *************** *********@4ax.c om...
On Fri, 1 Dec 2006 09:42:30 +0100, "Mike" <mi*****@nest or-tech.dot.com>
wrote:
>>Thanks for your help Doug
I believed I can do this
You can, but you'll get the weird results you got. :)
>>because my structures were not declared in the header files.
The header/source file distinction is irrelevant. The preprocessor
replaces
a #include directive with the indicated file's contents before the
compiler
even sees the code. It matters not a bit if a piece of code came from a
#include directive or was part of the #including file.
>>For me this error comes from the linker. The compiler cannot detect this kind of error because the structures are not declared in the header files.
The compiler cannot detect the error because the structs are defined in
different translation units, which the compiler compiles separately.
>>But I understand that these structures are in the global namespace, thanks for the tip.
I have a question about this problem : I have many many .cpp files, so I have to know all the local structures definitions names when I want to define another one in a .cpp ?
That problem is solved by anonymous namespaces.
>>And what happens if I use a library file instead of cpp files. If the lib has, somewhere, a local structure definition, how can I know the name of this structure if it is not declared in the headers ?
In general, you can't, and with anonymous namespaces, you don't have to.
>>so is it possible to have the same kind of error ?
Yep.
>>So, if I understand, I must always use an anonymous namespace everywhere I want to define a local structure ?
Yep. This was a real problem before namespaces were added to the language.
While "static" worked for global functions and data, it couldn't be
applied
to classes, which have linkage due to member functions (including
compiler-generated ones relevant to your example, i.e. ctors, dtors, and
assignment operator), static members, vtbls, etc.
--
Doug Harrison
Visual C++ MVP
This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
by: soni29 |
last post by:
hi,
i have written the following code, still in the learning stage:
#include<iostream.h>
class CBox {
public:
// Constructor definition
CBox(double lv, double bv = 1.0, double hv = 1.0) : m_Length(lv),
m_Breadth(bv), m_Height(hv)
|
by: Tom Lee |
last post by:
Hi,
I'm new to .NET 2003 compiler. When I tried to compile my
program using DEBUG mode, I got the following errors in the
C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7
\include\xdebug file as folows. I need help to resolve
them ASAP:
cl /c /nologo /MDd /W3 /Od /GR /GM /Zi /GX /D "_DEBUG" /D "
WIN32" /D "_W
INDOWS" /D "_WINDLL" /D "_AFXDLL" /D "_MBCS" /D "_USRDLL" /
|
by: Oliver Brausch |
last post by:
Hello,
have you ever heard about this MS-visual c compiler bug?
look at the small prog:
static int x=0;
int bit32() {
return ++x;
}
|
by: Bruno Jouhier [MVP] |
last post by:
I'm currently experiencing a strange phenomenon:
At my Office, Visual Studio takes a very long time to compile our solution
(more than 1 minute for the first project).
At home, Visual Studio compiles the same solution much faster (about 10
seconds for the first project).
My home computer is only marginally faster than the one I have at the office
(P4 2.53 vs. P4 2.4, same amount of RAM).
On the slow machine, the CPU usage is very low,...
|
by: el_sid |
last post by:
Our developers have experienced a problem with updating Web References in
Visual Studio.NET 2003.
Normally, when a web service class (.asmx) is created, updating the Web
Reference will utilise the disco file to update the
Corresponding proxy file and reflect the changes made to the web service.
However, the results of doing this with out params is that the results seem
| |
by: Zychrias |
last post by:
Using the following code:
typedef struct
{
FLOAT x, y, z; // Coordinates
D3DCOLOR dif; // Diffuse color
} sVertex;
sVertex Verts = {
{-100.0f, 100.0f, 100.0f, D3DCOLOR_RGBA(255, 255, 255, 255)},
|
by: kurt.kurtsmith |
last post by:
I am trying to import a tlb from a COM server(exe) I wrote with the
following statement:
#import "C:\\em2\\EM\\src\\core\\UMOSEFax\\Debug\\UMOSEFax.tlb"
no_namespace auto_search
the tlh and tli are generated in the debug directory but I get the
following error:
Error 1 error LNK2019: unresolved external symbol "long __cdecl
|
by: marathoner |
last post by:
I am currently migrating my Visual C++ 6.0 applications to Visual Studio
2005. I am getting compiler errors involving the VS2005's platform SDK.
When I removed directory references to that SDK, and started using the
Microsoft Platform SDK for XP SP2, the errors disappeared, but I am now
getting numerous warnings (macro redefinitions) as follows:
StdAfx.cpp
WINVER not defined. Defaulting to 0x0502 (Windows Server 2003)
C:\Program...
|
by: cpluslearn |
last post by:
Hi,
I have a local class inside a function template. I am able to wrap
any type in my local class. Is it legal C++? What type of class is
Local? Is it a class template or regular class?
Thanks in advance.
--dhina
---------------------------------------------------------------------------------------------------------------------------------------------
class Foo
{
public:
|
by: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look !
Part I. Meaning of...
|
by: Hystou |
last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it.
First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
| |
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it.
Here is my compilation command:
g++-12 -std=c++20 -Wnarrowing bit_field.cpp
Here is the code in...
|
by: jinu1996 |
last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth.
The Art of Business Website Design
Your website is...
|
by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own....
Now, this would greatly impact the work of software developers. The idea...
|
by: isladogs |
last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM).
In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules.
He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms.
Adolph will...
|
by: TSSRALBI |
last post by:
Hello
I'm a network technician in training and I need your help.
I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs.
The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols.
I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
|
by: 6302768590 |
last post by:
Hai team
i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
| |
by: bsmnconsultancy |
last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...
| |