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Old 06-28-2003, 12:14 PM   #1
djjumper9
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Registered: Jun 2003
Posts: 1

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Question G++ Linking Error "undefined reference"


I have a program which works on windows and I'm trying to run it on my mandrake linux 8.0 I am using g++ (version 2.96) to compile my c++ code to object code with the following command:
g++ -c *.cpp

When I try to link it with this command:
g++ *.o

I even created a makefile but that doesnt seem to help.

I get undefined reference errors to classes which i myself have created(I know that to link the math libray I need to add the -lm flag but I still get errors from my own classes) How would I get g++ to link my own files correctly? Any help is appreciated...
 
Old 06-28-2003, 12:40 PM   #2
kev82
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Registered: Apr 2003
Location: Lancaster, England
Distribution: Debian Etch, OS X 10.4
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let a.C and b.C contain classes a and b respectivly and let class b require class a. now if they get linked like this:

g++ b.C a.C

then all is well because the linker links b and is now looking for class a which it then finds, if however they are linked like this:

g++ a.C b.C

then the linker links class a and promptly forgets about it, then links class b which has a reference to class a it cant find, hence the unresolved external. so im guessing that *.o is picking out the files in lexographical order and some symbols are getting missed, provide the object files in the correct order and that might fix things.

HTH
 
Old 04-13-2004, 09:36 AM   #3
myra
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Registered: Apr 2002
Location: Austin, TX
Distribution: Red Hat 7.2
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more linker problems

Hello everyone...
I am having a more simple linker error with RedHat 7.2 g++... I have only one class and the program is just one file. To one function call I pass an array the class, and it works fine. To the next function, I pass it again, and I get unresolved external classname[i].memberfuntionname().

Any help would be much appreciated!

Thanks
Myra
 
  


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