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Re: C++ static member function reported as undefined references by linker?


David,

  As far as I know, they only have external linkage if the class has
external linkage.

Corey

On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> Can you help with this issue, in regards to C++ static member functions and why they are reported as undefined references by the linker?
>
> Please see attached email trail!
>
> Best Regards
> Daveed
> ________________________________________
> From: Paul
> Sent: Thursday, October 27, 2005 10:40 AM
> To: David Cespedes
> Subject: RE: Linux C++ implementation
>
> I don't know enough about Linux/gcc to help.
> static members are supposed to have external linkage--ARM Sec 9.4
>
> ________________________________________
> From: David Cespedes
> Sent: Thursday, October 27, 2005 11:46 AM
> To: Paul
> Subject: RE: Linux C++ implementation
> Yes, I did! I have a Sample.h for the definition and Sample.cpp where there is a void CSample::test(unsigned char foo) { ... } implementation.
>
> The only work-around I found is to implement the method function in the definition .H file (inline it) and I must declare the static member as an "extern bool CSample::m_bState" in order to see it, from an outside scope.
>
> ________________________________________
> From: Paul
> Sent: Thursday, October 27, 2005 10:40 AM
> To: David Cespedes
> Subject: RE: Linux C++ implementation
>
> Did you define (implement) the function somewhere?
> gcc is a very good compiler, I'm sure it follows all the standards.
>
> ________________________________________
> From: David Cespedes
> Sent: Thursday, October 27, 2005 11:02 AM
> To: Paul
> Subject: Linux C++ implementation
> Hi Paul!
>
> Once again I see myself baffled by a C++ questions and you are my last source for an educated answer. Anyhow, I have just started developing under the Linux platform using the gcc 2.96; do not ask why that version I do not control it.
>
> So I am working along and, by now, C++ is supposed to be C++ on any platform, until I declare a static method function and member in a class; see sample code. When I do this, if I try to use the global scope CSample::Test(...), the linker tells me that the function is an undefined reference???
>
> What happen here are? Did then gcc folks confuse the "C" vs. "C++" interpretation of a static scope? I need help...
>
> class CSample
> {
> public:
> CSample();
> ~CSample();
> static void test(unsigned char foo);
>
> protected:
> static bool m_bState;
> };
>
> Best regards,
>
> ________________________________________
> David A. Cespedes
> Chief Software Engineer - Manager
> I/O Marine Imaging Systems Division
> Office: 281.879.2171
>
>


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