Why am I getting linker errors?

[hopesfall]

So I have 6 linker errors which tell me some of my functions which are referenced in my .cpp file dont exist. These functions are in my .h file which I have included at the top of my .cpp file. This is how my project is set up:

//BST.h
class BinarySearchTree{
public:
//constructor and destructor
virtual void functiona(){};
virtual void functionb(){};
//overloaded operator
protected:
void functionC(){};
void functionD(){};
void functionE(){};
private:
int someValue;
};

//BST.cpp
#include "BST.h"

BinarySearchTree::BinarySearchTree(){
someValue = 1;
}
void BinarySearchTree::functiona{
   functionE();
}
void BinarySearchTree::functionb{
   functionD();
}

My compiler yells at me saying:

Error 33 error LNK2019: unresolved external symbol "protected: void __thiscall BinarySearchTree::functionE(class TreeNode *,void (__cdecl*)(class KeyedItem &))" (?postorder@BinarySearchTree@@IAEXPAVTreeNode@@P6AXAAVKeyedItem@@@Z@Z) referenced in function "public: virtual void __thiscall BinarySearchTree::functiona(void (__cdecl*)(class KeyedItem &))" (?postorderTraverse@BinarySearchTree@@UAEXP6AXAAVKeyedItem@@@Z@Z) C:\Users\izik\Documents\Visual Studio 2010\Projects\BSTInsertDelete\BST.obj BSTInsertDelete


What's going on here? Anyone have some speculations as to what I'm doing wrong?

[vlad from moscow]

The linker says very clear that it did not find such functions.
Can you point out for example where did you define function

void __thiscall BinarySearchTree::functionE(class TreeNode *,void (__cdecl*)(class KeyedItem &))"

???

[hopesfall]

Thanks for the reply. FunctionE is defined within the same class that function a is. I edited my original post to illustrate this.

[vlad from moscow]

The linker searches the function that takes two parameters the first of them is TreeNode *. Check your program to see where you call the function.

[Telion]

You didn't define functionE in the class; you declared it there. You need to define it in your cpp file like this:

//BST.cpp
#include "BST.h"

BinarySearchTree::BinarySearchTree(){
someValue = 1;
}
void BinarySearchTree::functiona{
   functionE();
}
void BinarySearchTree::functionb{
   functionD();
}

void BinarySearchTree::functionE{
   ++someValue;
}