Eerie Error while linking files c++

Question

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.

Answer 1

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.