virutal function in static library

[pipehappy]

Hi there,

I have came across a problem to make a library with virtual function.
I have example code listed below and if I compile this way it works:
g++ main.cpp a.cpp -o main
But when I want to have a static library it reports error:

g++ -c a.cpp -o liba.o
ar rcs liba.a liba.o
g++ -L. -la main.cpp -o main
/tmp/ccqQZO7f.o:(.rodata._ZTV4Base[vtable for Base]+0x10): undefined reference to `__cxa_pure_virtual' 

Anyone has any suggestion about this?

Thx

Here is the code example:

a.h:

#ifndef HE
#define HE
class Base {
    public:
        virtual double func(double)=0;
};

class Child: public Base{
    public:
        virtual double func(double);
};
#endif 

a.cpp:

#include "a.h"

double Child::func(double a) {
    return a+ 3;
}

main.cpp:

#include "a.h"

int
main (void) {
    Child child1;
    child1.func(0.3);
}

[guestgulkan]

write the function definition for the func function for the base class - even though it is pure virtual.
Should stop the compiler complaining.

I know it sounds weird - but if you have a pure virtual function which makes the class an abstract class and you therefore cannot create instances of the class - you can still give the function a body
(and you can call the function )