When I add a Retreive() method to my BST implementation I get a "unresolved external" compiler error.
The Retrieve() member function checks to see whether the value entered by the user exists in the BST, and if it does sets found = false.
//Header File
using namespace std;
struct PersonRec
{
char name[20];
int bribe;
PersonRec* leftLink;
PersonRec* rightLink;
};
class CTree
{
private:
PersonRec *tree;
bool IsEmpty();
void AddItem( PersonRec*&, PersonRec*);
void DisplayTree(PersonRec*);
void Retrieve(PersonRec*, PersonRec*,bool&);
public:
CTree();
//~CTree();
void Add();
void View();
};
//Implementation File
#include <iostream>
#include <string>
using namespace std;
#include "ctree.h"
CTree::CTree()
{
tree = NULL;
}
//PersonList::~MyTree()
//{
//
//}
bool CTree::IsEmpty()
{
if(tree == NULL)
{
return true;
}
else
{
return false;
}
}
void CTree::Add()
{
PersonRec* newPerson = new PersonRec();
cout << "Enter the person's name: ";
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
cin.getline(newPerson->name, 20);
cout << "Enter the person's contribution: ";
cin >> newPerson->bribe;
bool found = false;
newPerson->leftLink = NULL;
newPerson->rightLink = NULL;
Retrieve(tree, newPerson, found);
if (found)
cout << "Bribe allready entered\n";
else
AddItem(tree, newPerson);
}
void CTree::View()
{
if (IsEmpty())
{
cout<<"The list is empy";
}
else
{
DisplayTree(tree);
}
};
void CTree::AddItem( PersonRec*& ptr, PersonRec* newPer )
{
if (ptr == NULL)
{
ptr = newPer;
}
else if ( newPer->bribe < ptr->bribe)
AddItem(ptr->leftLink, newPer);
else
AddItem(ptr->rightLink, newPer);
}
void CTree::DisplayTree(PersonRec* ptr)
{
if (ptr == NULL)
return;
DisplayTree(ptr->rightLink);
cout<<ptr->name<<" "<<"$"<<ptr->bribe <<endl;
DisplayTree(ptr->leftLink);
}
void Retrieve(PersonRec*& ptr, PersonRec* newPer, bool& found)
{
{
if (ptr == NULL)
{
found = false; // item is not found.
}
else if ( newPer->bribe < ptr->bribe)
{
Retrieve(ptr->leftLink, newPer, found);
}
// Search left subtree.
else if (newPer->bribe > ptr->bribe)
{
Retrieve(ptr->rightLink, newPer, found);// Search right subtree.
}
else
{
//newPer.bribe = ptr->info; // item is found.
found = true;
}
}
}
//Driver File
#include <iostream>
using namespace std;
#include <cstdlib>
#include "ctree.h"
int displayMenu (void);
void processChoice(int, CTree&);
int main (void)
{
int num;
CTree ct;
do
{
num = displayMenu();
if (num != 3)
processChoice(num, ct);
} while (num != 3);
return 0;
}
int displayMenu (void)
{
int choice;
cout << "\nMenu\n";
cout << "==============================\n\n";
cout << "1. Add student to waiting list\n";
cout << "2. View waiting list\n";
cout << "3. Exit program\n\n";
cout << "Please enter choice: ";
cin >> choice;
return choice;
}
void processChoice(int choice, CTree& myTree)
{
switch (choice)
{
case 1: myTree.Add (); break;
case 2: myTree.View (); break;
}
}