Help!
I have three classes; Point, Neuron, and CumulativeNeuron. And I have source file neurones.cpp.
when I link my files it says:
~/Desktop/assign-8$ g++ point.o neuron.o cumulativeNeuron.o neurones.o
cumulativeNeuron.o:(.rodata._ZTI16CumulativeNeuron[_ZTI16CumulativeNeuron]+0x10): undefined reference to `typeinfo for Neuron'
collect2: error: ld returned 1 exit status
I can't understand this error! please help
Thanks.
You have forgotten to implement (or perhaps to link) the first virtual function in the Neuron class. Several compilers generate the RTTI type info for a class at the point where the first virtual function is implemented. If you forget to implement that function, no type info is generated and linking fails.
Related
compiling c++ from linux to windows using g++ and got an error.
Error:
undefined reference to `FOLDERID_RoamingTiles'
collect2: error: ld returned 1 exit status
I'm guessing there is a library I have to reference but I don't know what the name is.
also if that's the case what are the ways I could find the name of the library I have to reference, if that happens again in the future?
thanks.
I'm compiling under msys2/gcc. linking to uuid helped me.
g++ -luuid -o ....
I have the problem that as the g++ tries to link the object files I receive the following error:
11:29:13 **** Build of configuration Debug for project daytime ****
make all
'Building target: daytime'
'Invoking: Cross G++ Linker'
g++ -o "daytime" ./tcf/services/daytime.o ./tcf/main/main.o
./tcf/services/daytime.o: In function `command_get_time_of_day':
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:38: undefined reference to `json_read_string'
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:40: undefined reference to `exception'
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:43: undefined reference to `exception'
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:52: undefined reference to `write_stringz'
makefile:46: recipe for target 'daytime' failed
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:54: undefined reference to `write_stringz'
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:56: undefined reference to `write_errno'
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:58: undefined reference to `json_write_string'
./tcf/services/daytime.o: In function `ini_daytime_service':
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:70: undefined reference to `add_command_handler'
collect2.exe: error: ld returned 1 exit status
make: *** [daytime] Error 1
I have no idea why this is the case since e.g. #include <tcf/framework/json.h>is included and found.
Didn't gcc compile the corresponding *.c files such that this linker error occurs?
What is the problem here?
Thank you.
It is not enough to include the header files; you also have to specify the libraries where those functions are defined.
To make the linker find all those methods/classes (json_read_string, write_stringz, exception) you need to reference the library. If e.g. they are contained in a library called libjson.so, you should do:
g++ -ljson -o "daytime" ./tcf/services/daytime.o ./tcf/main/main.o
(or add the library to the project options, if eclipse is managing your make files).
Or if it's another .o file, include that in the compilation (-> or in the project, if eclipse is creating the make file).
I'm pretty new to C++ and I'm trying to compile my code. The command I'm using is g++ -o main --std=c++11 main.cpp channel.cpp. However I'm getting the following error message:
/tmp/ccLuJs81.o: In function `main':
main.cpp:(.text+0x26): undefined reference to `gsc::Channel<int>::Channel()'
main.cpp:(.text+0x3a): undefined reference to `gsc::Channel<int>::put(int)'
main.cpp:(.text+0x4e): undefined reference to `gsc::Channel<int>::get(bool)'
collect2: error: ld returned 1 exit status
Does anyone know what's going on here? Thanks a lot!
Seems you declared a template in a header and defined it in a C++ file. This won't work. If you don't define your template in a header, you need to explicitly instantiate it in your C++ file, e.g. ,using
template class gcs::Channel<int>;
after the definition of all the methods.
everyone
Recently, I'm working on stereo vision. And I download the StereoMatch code from middlebury website: http://vision.middlebury.edu/stereo/code/
I used Ubuntu 11.10 to run this code. After I run this code, I got the following error. There are 3 'undefined reference to ' error. But the code has already included the header file 'MinFilter.h'. And I get confused. Could someone help me? I would appreciate it.
errors:
StcAggregate.o: In function CStereoMatcher::AggrMin()':
StcAggregate.cpp:(.text+0x20f): undefined reference tovoid MinFilter(CImageOf&, CImageOf&, int, int)'
StcEvaluate.o: In function _ZL14PartialShuffle8CImageOfIhERS0_S1_f.constprop.2':
StcEvaluate.cpp:(.text+0x37): undefined reference tovoid MinFilter(CImageOf&, CImageOf&, int, int)'
StcEvaluate.cpp:(.text+0x5b): undefined reference to `void MaxFilter(CImageOf&, CImageOf&, int, int)'
collect2: ld returned 1 exit status
make: * [StereoMatch] Error 1
This is an error from the linker (and/or runtime environment) which cannot find some symbols (i.e. code) which the header files you've included promised to exist. In order for these symbols to be found, you must tell the linker to link against the library (or object file) containing them. This library may have come with the code pre-compiled or may have been made during installation. Have you not got a README file where it is explained how to use (i.e. link and run) the code?
I met exactly the same problem and solved it like this:
Open the Makefile and change the first line from
CPPFLAGS = -O2 -Wall
to
CPPFLAGS = -O -Wall
Then "make clean" and "make", it works for me. So I guess it is because param
"-O2" does more optimization than expected.
I follow this PJLIB ( https://trac.pjsip.org/repos/wiki/Getting-Started/Autoconf ). But i cant get this up yet, always its giving undefined reference, can anyone please have a look kindly.
Stackoverlow source code gets broken please find from
here details: http://gist.github.com/5765529
[sun#example mysip]$ gcc myapp.c
/tmp/ccEKxwjG.o: In function `main':
myapp.c:(.text+0xa): undefined reference to `pjsua_create'
collect2: ld returned 1 exit status
Thank you
You are not linking with the library. You need something like:
gcc myapp.c -lpjlib
but exactly what you need I don't know - it will be described in the library's documentation.