From:	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Newsgroups:	comp.os.msdos.djgpp,comp.lang.c++
Subject:	Re: Problems defining external symbols in C++ !?
Date:	8 Feb 2001 12:44:32 GMT
Organization:	Aachen University of Technology (RWTH)
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In comp.os.msdos.djgpp Attila Feher <Attila DOT Feher AT lmf DOT ericsson DOT se> wrote:
> Oliver Richman wrote:
>> 
>> I am converting a large C program to C++ using DJGPP, and all is going
>> well, but for some reason when I do this:
>> 
>> from moo.cc:
>> const struct moostruct moovariable[] = { ... }
>> 
>> from moo2.cc:
>> extern const struct moostruct moovariable[];
>> 
>> I get an "undefined reference to moovariable" in moo2.cc.

> I assume it is a compiler and not linker error.  

I strongly doubt that. "undefined reference" *is* a linker error.  You
probably tried to compile moo2.cc to an executable on its own, without
linking moo.o to it.

	g++ -O2 -o moo2.exe moo2.cc moo.cc 

should work.

> moo2.cc!  How is moo2.cc supposed to know the size, the data members
> etc. of your struct?  You need to make (using a header file usually)
> moo2.cc to know the structure of the structure :-))

If that had been the problem the compiler would have complained,
giving an error message like 'reference to incompletely defined
datatype'.
-- 
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.

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