Very Computer

Hello,

I have an project with an abstract class ca_field and two
implementations of this class (ca_grid and ca_planar). No error occurs
when I compile the project, but the linker says:

ca_grid.o: In function `ca_grid type_info function':
ca_grid.o(.text+0x270d): undefined reference to `ca_field type_info
function'
ca_grid.o(.text+0x2714): undefined reference to `ca_field type_info
node'
ca_grid.o: In function `ca_field::ca_field(void)':
ca_grid.o(.ca_field::gnu.linkonce.t.(void)+0x8): undefined reference
to `ca_field virtual table'
ca_planar.o: In function `ca_planar type_info function':
ca_planar.o(.text+0x212d): undefined reference to `ca_field type_info
function'
ca_planar.o(.text+0x2134): undefined reference to `ca_field type_info
node'
GNU ld version 2.9.1 (with BFD 2.9.1.0.15)
  Supported emulations:
  elf_i386
  i386linux
collect2: ld returned 1 exit status

I'am using
gcc version egcs-2.91.60 19981201 (egcs-1.1.1 release)

Whats the problem ?

thanks
Steffen

Sounds like your inherited classes (ca_grid and ca_planar) don't know
about the base class ca_field.  Do you have a #include to the base
class definition/member functions in your inherited class definition
files?  Something like:

  File with ca_grid class definition:
   #include "ca_field.h"

     class ca_planar : public ca_field
     { // stuff };

Regards,

Ed Holloman

: Sounds like your inherited classes (ca_grid and ca_planar) don't know
: about the base class ca_field.  Do you have a #include to the base
: class definition/member functions in your inherited class definition
: files?  Something like:
:
:   File with ca_grid class definition:
:    #include "ca_field.h"
:
:      class ca_planar : public ca_field
:      { // stuff };
:
: Regards,
:
: Ed Holloman
Thanks,

but I have included the base class :-( Some background informations: The
project is written in C and only this three classes are C++.

bye Steffen

Quote:> Hello,

> I have an project with an abstract class ca_field and two
> implementations of this class (ca_grid and ca_planar). No
error occurs
> when I compile the project, but the linker says:

> ca_grid.o(.ca_field::gnu.linkonce.t.(void)+0x8): undefined
reference
> to `ca_field virtual table'

Please attach some of your code next time you post.
The above error may be because you have forgotten to
declare a virtual destructor (even if it's a do nothing
dtor) in the abstract base class. Check all your declarations
for missing virtual modifiers - without these the virtual
table may be missing or incomplete.
Joseph

--
  This answer is courtesy of QuestionExchange.com
  http://www.questionexchange.com/showUsenetGuest.jhtml?ans_id=7719&cus...

: > to `ca_field virtual table'
: Please attach some of your code next time you post.
At the time I have found this error, the code was to big and can't
construct an simple example.
Now I have found the error, an forgotten =0 in my abstract class :-(
Is there an tool which find this error?

bye Steffen
: The above error may be because you have forgotten to
: declare a virtual destructor (even if it's a do nothing
: dtor) in the abstract base class. Check all your declarations
: for missing virtual modifiers - without these the virtual
: table may be missing or incomplete.
: Joseph
:
: --
:   This answer is courtesy of QuestionExchange.com
:   http://www.questionexchange.com/showUsenetGuest.jhtml?ans_id=7719&cus...