about inheritance in C++, can a derived class get implemetation from base class without explicitly defining it -

the following has error

error lnk2001: unresolved external symbol "public: virtual void __thiscall c::foo(void)" (?foo@c@@uaexxz)

so c::test() cannot inherit implementation of b::test() automatically , have explicitly write everytime in c++?

class {  public:       virtual void foo()=0;     virtual void test()=0;  };  class b: public  { public:      virtual void foo();     virtual void test()=0;  };  void b::foo() {  }    class c: public b { public:     void foo();     void test(); };    void c::test() { } 

if derived class declares virtual method parent class, c void foo(), must implement too. if want inherit b's implementation, don't declare void foo() in c.

class c: public b { public:     void test(); };