Error: TYpe B is incomplete, can anyone help?

Question

I got a "type B is incomplete" error when using studio12 CC to compile the following code on Solaris 9.
Anyone knows what's going on?
#include<set>
class B;
struct b_compare{
bool operator()(B* const &a, B* const &b) const
return strcmp(a->getname(),b->getname())<0;
class B {
char * a;
public:
std::set<B *, b_compare> setb;
char * getname() const {return a;}
main()
Thanks in advance...

Answer 1

An incomplete class type can be used only to declare a pointer to the type. You cannot use a member of a class until the class definition has been seen.
Move the definition of class B to a point ahead of the first use of a B member. It's always possible to do that. For classes that reference members of each other, you might need to define member functions outside the class, after both of the class definitions.
Example: class A;
class B {
public:
    int foo(A*);
    int g();
class A {
    int bar(B*);
    int g();
int A::bar(B* b) { return b->g(); }
int B::foo(A* a) { return a->g(); }