LNK2001 error

I created a VC++ solution. The solution has several project:
- One static library project named "Common".
- Several other dll project that link the library project. I've checked the
"Common" in the project dependence dialog box. Also I've tried to add
reference to Common ("References... -> add new reference").

However, I always got the errors:

Error 13 error LNK2001: unresolved external symbol "public: virtual class
std::basic_string<char,struct std::char_traits<char>,class
std::allocator<char> > __thiscall Param<class CEmpty<double> >::toStr(void)"
(?toStr@?$InParam@V?$CEmpty@N@@@@UAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ) proc.obj

What I missed?

Thanks.

Marcus
Thu Apr 13 02:54:11 CDT 2006

Adding references is only useful for managed assemblies.

To use parts from your native .lib, use the .lib file as a linker input for
you other projects and set the project dependeny manually.

Marcus Heege
www.heege.net

"nick" <nick@discussions.microsoft.com> wrote in message
news:9D226C27-7F30-4C0A-A63A-BEEA7287A8F3@microsoft.com...
>I created a VC++ solution. The solution has several project:
> - One static library project named "Common".
> - Several other dll project that link the library project. I've checked
> the
> "Common" in the project dependence dialog box. Also I've tried to add
> reference to Common ("References... -> add new reference").
>
> However, I always got the errors:
>
> Error 13 error LNK2001: unresolved external symbol "public: virtual class
> std::basic_string<char,struct std::char_traits<char>,class
> std::allocator<char> > __thiscall Param<class CEmpty<double>
> >::toStr(void)"
> (?toStr@?$InParam@V?$CEmpty@N@@@@UAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
> proc.obj
>
> What I missed?
>
> Thanks.

Ulrich
Thu Apr 13 03:42:38 CDT 2006

Marcus Heege wrote:
> Adding references is only useful for managed assemblies.
>
> To use parts from your native .lib, use the .lib file as a linker input
> for you other projects and set the project dependeny manually.

Just for your info, you don't have to explicitly list a library or DLL as
linker inputs if they are in the same workspace and marked as dependency of
the project that uses them. Neat feature, IMHO.

Uli

Marcus
Thu Apr 13 06:35:01 CDT 2006

"Ulrich Eckhardt" <eckhardt@satorlaser.com> wrote in message
news:eff1h3-vdm.ln1@satorlaser.homedns.org...
> Marcus Heege wrote:
>> Adding references is only useful for managed assemblies.
>>
>> To use parts from your native .lib, use the .lib file as a linker input
>> for you other projects and set the project dependeny manually.
>
> Just for your info, you don't have to explicitly list a library or DLL as
> linker inputs if they are in the same workspace and marked as dependency
> of
> the project that uses them. Neat feature, IMHO.
>
> Uli
>

Very nice feature. Indeed.

Igor
Thu Apr 13 07:19:41 CDT 2006

"nick" <nick@discussions.microsoft.com> wrote in message
news:9D226C27-7F30-4C0A-A63A-BEEA7287A8F3@microsoft.com
> However, I always got the errors:
>
> Error 13 error LNK2001: unresolved external symbol "public: virtual
> class
> std::basic_string<char,struct std::char_traits<char>,class
> std::allocator<char> > __thiscall Param<class CEmpty<double>
> >::toStr(void)"
> (?toStr@?$InParam@V?$CEmpty@N@@@@UAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
> proc.obj

Have you by any chance implemented methods of a template class in a .cpp
file? That's not going to work. The compiler needs to see the
implementation at the point the template is used, so the code has to be
in .h file.
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925

nick
Thu Apr 13 08:45:03 CDT 2006

Yes, I've implemented methods of template class in a .cpp file. Does it mean
we must use inline function for method of template classes?

"Igor Tandetnik" wrote:

>
> Have you by any chance implemented methods of a template class in a .cpp
> file? That's not going to work. The compiler needs to see the
> implementation at the point the template is used, so the code has to be
> in .h file.
> --
> With best wishes,
> Igor Tandetnik
>
> With sufficient thrust, pigs fly just fine. However, this is not
> necessarily a good idea. It is hard to be sure where they are going to
> land, and it could be dangerous sitting under them as they fly
> overhead. -- RFC 1925
>
>
>

Abdo
Thu Apr 13 10:25:04 CDT 2006

"nick" <nick@discussions.microsoft.com> wrote in message
news:F0AA0D78-3080-4807-8B12-EC134B1D2E26@microsoft.com...
> Yes, I've implemented methods of template class in a .cpp file. Does it
mean
> we must use inline function for method of template classes?
>


Not necessarily inline, but you have to include the implementation in the
header...

--
Abdo Haji-Ali
Programmer
In|Framez

nick
Thu Apr 13 11:09:01 CDT 2006

I've used the inline function and so I moved the definition of the method to
head file. However, I have new Link error?

Error 1 error LNK2005: "public: __thiscall std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> >::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> >(char const *)"
(??0?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@PBD@Z)
already defined in common.lib(Common.obj) msvcprtd.lib



"Igor Tandetnik" wrote:

> "nick" <nick@discussions.microsoft.com> wrote in message
> news:9D226C27-7F30-4C0A-A63A-BEEA7287A8F3@microsoft.com
> > However, I always got the errors:
> >
> > Error 13 error LNK2001: unresolved external symbol "public: virtual
> > class
> > std::basic_string<char,struct std::char_traits<char>,class
> > std::allocator<char> > __thiscall Param<class CEmpty<double>
> > >::toStr(void)"
> > (?toStr@?$InParam@V?$CEmpty@N@@@@UAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
> > proc.obj
>
> Have you by any chance implemented methods of a template class in a .cpp
> file? That's not going to work. The compiler needs to see the
> implementation at the point the template is used, so the code has to be
> in .h file.
> --
> With best wishes,
> Igor Tandetnik
>
> With sufficient thrust, pigs fly just fine. However, this is not
> necessarily a good idea. It is hard to be sure where they are going to
> land, and it could be dangerous sitting under them as they fly
> overhead. -- RFC 1925
>
>
>

Igor
Thu Apr 13 21:25:01 CDT 2006

"nick" <nick@discussions.microsoft.com> wrote in message
news:0EC4D8C2-CBFD-439E-9DB9-40CACC169AB9@microsoft.com
> I've used the inline function and so I moved the definition of the
> method to head file. However, I have new Link error?
>
> Error 1 error LNK2005: "public: __thiscall
> std::basic_string<char,struct std::char_traits<char>,class
> std::allocator<char> >::basic_string<char,struct
> std::char_traits<char>,class std::allocator<char> >(char const *)"
> (??0?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE@PBD@Z)
> already defined in common.lib(Common.obj) msvcprtd.lib

You are using a static library that is built against a different CRT
flavor than the rest of your application. Make sure all projects use
consistent compiler options.
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925