linker error during signal declaration

1.inside a.h
2.#include "b.h"
3.class A:public QObject
4.{
5.Q_OBJECT
6.public:
7.A();
8.public:
9.B *b;
10.slot:
11.A* retobj();
12.};
13.inside a.cpp
14.A::A()
15.{
16.b= new B();
17. QObject::connect(b,SIGNAL(returnObj(),this,SLOT(re tobj()));
18.
19.}
20.A * A::retobj()
21.{
22.return this ;
23.}
24.//----------------
25.inside b.h
26.
27.class A; //forward declaration
28.class B:public QObject
29.{
30.Q_OBJECT
31.public:
32.B();
33.A *a1;
34.public:
35.void hello();
36.signal:
37.A* returnObj();
38.};
39.//------------------
40.inside b.cpp
41.B::B()
42.{
43.
44.}
45.void B::hello()
46.{
47.a1= emit returnObj();
48.}
49.//------------------
50.inside main
51.
52.#include "a.h"
53.#include"b.h"
54.int main()
55.{
56.A * a2= new A();
57.B * b2=new B();
58.b->hello();
59.}
60.//-------------------------

The above code is compiling but during linking its showing some problem ..something like unresolved external symbol returnObj();
What might be the reason ..
Thankx in adv ..

My eyes are bleeding. For the sake of everyone's eyes please use [code]...[/code] tags around you code. The forum will preserve indenting, suppress the smileys, and even number the lines for you.

This code cannot compile as presented.

• a.cpp will not compile as presented: there is no declaration of A.
• There no inclusion of any Qt header to declare QObject.
• Line 10 "slot" does not name a type
• Line 17 mismatched parentheses
• Line 36 "signal" does not name a type
• There is no variable b in scope at line 58.
• Redefinition of class B because there are no include guards
• More that I'd be wasting time listing.

Even if it did compile:

• Line 16 and 17. A creates a private B and connects that to its slot. You never use this 'b'.
• Line 11. Slots can return values when called as a normal function, but not through a signal/slot connection.
• Line 37. Signals do not return values
• Line 47. Signals do not return values