Compiling class calling another class

I have two classes, class A and class B. Class B has class A as a member. I’ve been having an issue when trying to compile class B using the following in root .L classB.cxx+ I get an error message about undefined references to methods of class A. What am I missing? I have included the proper headers, but I still have an issue. Below is a simple example of the issue and the resulting error.

Here is the code classA.h

[code]#ifndef CLASSA_H
#define CLASSA_H

#include “TROOT.h”

class A
{
private:
Float_t fX;
public:
A(Float_t x);
Float_t GetX();

ClassDef(A,1)

};

#endif[/code]

classA.cxx:

#include "classA.h"

ClassImp(A)

A::A (Float_t x)
{
	fX = x;
}

Float_t A::GetX)
{
	return fX;
}

classB.h:

[code]#ifndef CLASSB_H
#define CLASSB_H

#include “TROOT.h”
#include “classA.h”

class B
{
private:
Float_t fY;
A *fA;
public:
B(Float_t y);
Float_t GetY();

ClassDef(B,1)

};

#endif[/code]

classB.cxx:

[code]#include “classB.h”
#include “classA.h”

B::B(Float_t y)
{
fY = y;
fA = new A(fY);
}

Float_t B::GetY()
{
return fA->GetX();
}
[/code]

I can compile classA with no issues.
To compile classB I use .L classB.cxx+
I then get an error message about classA /research/S323/DAQsvn/beta-n_analysis/trunk/source/errorExample/classB_cxx_ACLiC_dict.o: In function `B::B(float)': classB_cxx_ACLiC_dict.cxx:(.text+0x114a): undefined reference to `A::A(float)' /research/S323/DAQsvn/beta-n_analysis/trunk/source/errorExample/classB_cxx_ACLiC_dict.o: In function `B::GetY()': classB_cxx_ACLiC_dict.cxx:(.text+0x1285): undefined reference to `A::GetX()' collect2: ld returned 1 exit status Error in <ACLiC>: Compilation failed!

root [0] .L classA.cxx++ root [1] .L classB.cxx++
See also [url]Simple way to create and merge shared libraries?