undefined reference to `vtable for class

Question

I have take code from cppfaq 12.15 and trying to compile but getting error in linux with gcc version 4.8.4.

undefined reference to `vtable for

I am surprise as I do not have any virtual method. I have looked into following question but not able figure out issue.

The code

#include<iostream>
#include<new>
#include<memory> using namespace std;

class Fred; typedef auto_ptr<Fred> FredPtr;

class Fred {
    public:
        static FredPtr create() throw(bad_alloc);
        static FredPtr create(int i) throw(bad_alloc);
        static FredPtr create(const Fred& x) throw(bad_alloc);
        virtual void goBowling();
    private:
        Fred(int i=10);
        Fred(const Fred& x);
        int i_;
    };

FredPtr Fred::create() throw (bad_alloc) {   return auto_ptr<Fred>(new Fred()); }

FredPtr Fred::create(int i) throw(bad_alloc) {
    return auto_ptr<Fred>(new Fred(i)); }

FredPtr Fred::create(const Fred& x) throw(bad_alloc) {
    return auto_ptr<Fred>(new Fred(x)); }

Fred::Fred(int i) {
    i_ = i;
    cout<<" This is simple constructor"<<endl; }

Fred::Fred(const Fred& x) {
    i_ = x.i_;
    cout<<" This is copy constrcutor"<<endl; }

void sample() {
    FredPtr p(Fred::create(5));
    p->goBowling(); }

int main() {
    sample();
    return 0; }

Error:

/tmp/cc6JnLMO.o: In function `Fred::Fred(int)':
cpp12_15.cpp:(.text+0x204): undefined reference to `vtable for Fred'
/tmp/cc6JnLMO.o: In function `Fred::Fred(Fred const&)':
cpp12_15.cpp:(.text+0x247): undefined reference to `vtable for Fred'
collect2: error: ld returned 1 exit status

http://www.cplusplus.com/reference/memory/auto_ptr/ - see the *deprecated* note — Karoly Horvath, Jul 07 '15 at 07:08
You should define a `public: virtual ~Fred() {}` destructor. — πάντα ῥεῖ, Jul 07 '15 at 07:09
Usually this error means that you forgot to include the function body for some other function — M.M, Jul 07 '15 at 07:09
You say you have no virtual functions, yet you have `virtual void goBowling();`.... — Michael Anderson, Jul 07 '15 at 07:14
but why should I define virtual destructor, Can I not write class without virtual destructor — user765443, Jul 07 '15 at 07:15
You can certainly write a class without a virtual destructor if you know what the limitations of doing that are.... but usually its not what you want. — Michael Anderson, Jul 07 '15 at 07:16

score 3 · Answer 1 · answered Jul 07 '15 at 08:08

3

As long as you have a virtual keyword in you class definition the compiler will build statically the vtable even if you're not inheriting from it, as you can see in your class you didn't define your goBowling method so compilation will fail.

answered Jul 07 '15 at 08:08

Anis Belaid

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undefined reference to `vtable for class

1 Answers1