BinaryTree search function - c++

Question

The program should ask the user to enter the ID number of the employee he or she wants to search for. If it is found the employee of that ID number is displayed. I can display the ID numbers and employees just by using the display functions but I can't figure out how to make the search function work and display the employees.
BINARYTREE
#ifndef BINARYTREE_H
#define BINARYTREE_H
#include <iostream>
using namespace std;
// This class is a template class that creates a binary
// tree that can hold values of any data type. It has
// functions to insert a node, delete a node, display the
// tree In Order, Pre Order and Post Order, search for a
// value, count the number of total nodes, left nodes,
// and a function to determine the height of the tree.
template <class T>
class BinaryTree
{
private:
struct TreeNode
{
T value; // The value in the node
TreeNode *left; // Pointer to left child node
TreeNode *right; // Pointer to right child node
};
TreeNode *root; // Pointer to the root node
// Private member functions
void insert(TreeNode *&, TreeNode *&);
void destroySubTree(TreeNode *);
void deleteNode(T, TreeNode *&);
void makeDeletion(TreeNode *&);
void displayInOrder(TreeNode *) const;
void displayPreOrder(TreeNode *) const;
void displayPostOrder(TreeNode *) const;
public:
// Constructor
BinaryTree()
{ root = NULL; }
// Destructor
~BinaryTree()
{ destroySubTree(root); }
// Binary tree operations
void insertNode(T);
bool searchNode(int);
void remove(T);
void displayPreOrder() const
{ displayPreOrder(root); }
void displayInOrder() const
{ displayInOrder(root); }
void displayPostOrder() const
{ displayPostOrder(root); }
};
//*********************************************************
// insert function accepts a TreeNode pointer and a *
// pointer to a node. The function inserts the node into *
// the tree pointer to by the TreeNode pointer. This *
// function is call recursively. *
//*********************************************************
template <class T>
void BinaryTree<T>::insert(TreeNode *&nodePtr, TreeNode *&newNode)
{
if (nodePtr == NULL)
nodePtr = newNode; // Insert the node
else if (newNode->value < nodePtr->value)
insert(nodePtr->left, newNode); // Search the left branch
else
insert(nodePtr->right, newNode);// Search the right branch
}
//*********************************************************
// insertNode creates a new node to hold item as its value*
// and passes it to the insert function. *
//*********************************************************
template <class T>
void BinaryTree<T>::insertNode(T item)
{
TreeNode *newNode; // Pointer to a new node
// Create anew node and store num in it
newNode = new TreeNode;
newNode->value = item;
newNode->left = newNode->right = NULL;
// Insert the node
insert(root, newNode);
}
//**********************************************************
// destroySubTree is called by the destructor. It deletes *
// all nodes in the tree. *
//**********************************************************
template <class T>
void BinaryTree<T>::destroySubTree(TreeNode *nodePtr)
{
if (nodePtr)
{
if (nodePtr->left)
destroySubTree(nodePtr->left);
if (nodePtr->right)
destroySubTree(nodePtr->right);
delete nodePtr;
}
}
//**********************************************************
// searchNode determines if a value is present in the tree.*
// If so, the function returns true. Otherwise it returns *
// false.
//**********************************************************
template <class T>
bool BinaryTree<T>::searchNode(T item)
{
TreeNode *nodePtr = root;
while (nodePtr)
{
if (nodePtr->value == item)
return true;
else if (item < nodePtr->value)
nodePtr = nodePtr->left;
else
nodePtr = nodePtr->right;
}
return false;
}
//*********************************************************
// remove calls deleteNode to delete the node whode value *
// member is the same as num *
//*********************************************************
template <class T>
void BinaryTree<T>::remove(T item)
{
deleteNode(item, root);
}
//*********************************************************
// deleteNode deletes the node whose value member is the *
// same as num *
//*********************************************************
template <class T>
void BinaryTree<T>::deleteNode(T item, TreeNode *&nodePtr)
{
if (item < nodePtr->value)
deleteNode(item, nodePtr->left);
else if (item > nodePtr->value)
deleteNode(item, nodePtr->right);
else
makeDeletion(nodePtr);
}
//*********************************************************
// makeDeletion takes a reference to apointer to the node *
// that is to be deleted. The node is removed and the *
// branches of the tree below the node are reattached *
//*********************************************************
template <class T>
void BinaryTree<T>::makeDeletion(TreeNode *&nodePtr)
{
// Define a temporary pointer to use in reattaching
// the left subtree
TreeNode *tempNodePtr;
if (nodePtr == NULL)
cout << "Cannot delete empty node.\n";
else if (nodePtr->right == NULL)
{
tempNodePtr = nodePtr;
nodePtr = nodePtr->left; // Reattach the left child
delete tempNodePtr;
}
else if (nodePtr->left == NULL)
{
tempNodePtr = nodePtr;
nodePtr = nodePtr->right; // Reattach the right child
delete tempNodePtr;
}
}
//*********************************************************
// The displayInOrder function displays the values in the *
// subtree pointed to by nodePtr, via inorder traversal *
//*********************************************************
template <class T>
void BinaryTree<T>::displayInOrder(TreeNode *nodePtr) const
{
if (nodePtr)
{
displayInOrder(nodePtr->left);
cout << nodePtr->value.getEmpID() << " "
<< nodePtr->value.getEmpName() << endl;
displayInOrder(nodePtr->right);
}
}
//*********************************************************
// The displayPreOrder function displays the values in the*
// subtree pointed to by nodePtr, via Preorder traversal *
//*********************************************************
template <class T>
void BinaryTree<T>::displayPreOrder(TreeNode *nodePtr) const
{
if (nodePtr)
{
cout << nodePtr->value.getEmpID() << " "
<< nodePtr->value.getEmpName() << endl;
displayInOrder(nodePtr->left);
displayInOrder(nodePtr->right);
}
}
//*********************************************************
// displayPostOrder function displays the values in the *
// subtree pointed to by nodePtr, via Postorder traversal *
//*********************************************************
template <class T>
void BinaryTree<T>::displayPostOrder(TreeNode *nodePtr) const
{
if (nodePtr)
{
displayInOrder(nodePtr->left);
displayInOrder(nodePtr->right);
cout << nodePtr->value.getEmpID() << " "
<< nodePtr->value.getEmpName() << endl;
}
}
#endif
EMPLOYEEINFO
#ifndef EMPLOYEEINFO_H
#define EMPLOYEEINFO_H
#include <string>
#include <iostream>
using namespace std;
// This class has two data members to hold the employee ID
// and the name of the employee.
class EmployeeInfo
{
private:
int empID; // To hold employee ID number
string empName; // To hold employee name
public:
// Default Constructor
EmployeeInfo();
// Constructor
EmployeeInfo(int, string);
// Mutators
void setEmpID(int);
void setEmpName(string);
// Accessors
int getEmpID();
string getEmpName();
// Overloaded operator. This works directly with
// the insert function of BinaryTree.h more specifically
// line 71. *For my knowledge*
bool operator < (const EmployeeInfo &e)
{
if (empID < e.empID)
return true;
return false;
}
// Overloaded operator for the search function
bool operator == (const EmployeeInfo &e)
{
if (empID == e.empID)
return true;
return false;
}
};
#endif
#include "EmployeeInfo.h"
//*********************************************************
// Default constructor intializes the data members *
//*********************************************************
EmployeeInfo::EmployeeInfo()
{
empName = "";
empID = 0;
}
//*********************************************************
// Constructor sets the data members *
//*********************************************************
EmployeeInfo::EmployeeInfo(int ID, string name)
{
empName = name;
empID = ID;
}
//*********************************************************
// setEmpID stores the employee ID number *
//*********************************************************
void EmployeeInfo::setEmpID(int ID)
{
empID = ID;
}
//*********************************************************
// setEmpName stores the full name of the employee *
//*********************************************************
void EmployeeInfo::setEmpName(string name)
{
empName = name;
}
//*********************************************************
// getEmpID returns the employee ID number *
//*********************************************************
int EmployeeInfo::getEmpID()
{
return empID;
}
//*********************************************************
// getEmpName returns the full name of the employee *
//*********************************************************
string EmployeeInfo::getEmpName()
{
return empName;
}
MAIN
#include "EmployeeInfo.h"
#include "BinaryTree.h"
#include <iostream>
using namespace std;
int main()
{
// Create an instance of BinaryTree
BinaryTree<EmployeeInfo> tree;
// Create an EmployeeInfo object
EmployeeInfo emp1(1021, "John Williams");
EmployeeInfo emp2(1057, "Bill Witherspoon");
EmployeeInfo emp3(2487, "Jennifer Twain");
EmployeeInfo emp4(3769, "Sophia Lancaster");
EmployeeInfo emp5(1017, "Debbie Reece");
EmployeeInfo emp6(1275, "George McMullen");
EmployeeInfo emp7(1899, "Ashley Smith");
EmployeeInfo emp8(4218, "Josh Plemmons");
tree.insertNode(emp1);
tree.insertNode(emp2);
tree.insertNode(emp3);
tree.insertNode(emp4);
tree.insertNode(emp5);
tree.insertNode(emp6);
tree.insertNode(emp7);
tree.insertNode(emp8);
// Search for an employee
char again = 'y'; // To hold yes
int id; // To hold ID number from user
cout << "Would you like to search for an employee?\n";
cout << "Enter Y for yes or N for No: ";
cin >> again;
if (again)
{
do
{
cout << "Enter the ID number of the employee: ";
cin >> id;
// Create an EmployeeInfo object to store the user's
// search parameters
EmployeeInfo info;
info.setEmpID(id);
// If search finds what the user entered display the
// corresponding employee
if (tree.searchNode(info))
{
cout << info.getEmpName() << endl; // Not right?
}
else
cout << "ID not found!" << endl;
cout << "Would you like to search for an employee?\n";
cout << "Enter Y for yes or N for No: ";
cin >> again;
}while (again == tolower('Y'));
}
// Display in order
tree.displayInOrder();
cout << endl;
tree.displayPreOrder();
cout << endl;
tree.displayPostOrder();
}
Ok I changed the code up to get the bool to work and the if (tree.searchNode(info)) but I don't think the cout statement is right. Can someone look at my searchNode function and how I called it in main and let me know what I'm doing wrong?

Answer 1

Problem lies here
info.setEmpID(1021);
info.setEmpID(1057);
info.setEmpID(2487);
info.setEmpID(3769);
info.setEmpID(1017);
info.setEmpID(1275);
info.setEmpID(1899);
info.setEmpID(4218);
info.setEmpName("John Williams");
info.setEmpName("Bill Witherspoon");
info.setEmpName("Jennifer Twain");
info.setEmpName("Sophia Lancaster");
info.setEmpName("Debbie Reece");
info.setEmpName("George McMullen");
info.setEmpName("Ashley Smith");
info.setEmpName("Josh Plemmons");
You are not adding anything to info but every time you call setEmpName() you are updating info object.
You can make few changes in searchNode method as below
template <class T>
bool BinaryTree::searchNode(T &item)
{
TreeNode *nodePtr = root;
while (nodePtr)
{
if (nodePtr->value == item)
{
item.setEmpName(nodePtr->value.getEmpName());
return true;
}
else if (item < nodePtr->value)
nodePtr = nodePtr->left;
else
nodePtr = nodePtr->right;
}
return false;
}
In main() method
do
{
cout << "Enter the ID number of the employee: ";
cin >> id;
BinaryTree<EmployeeInfo> temp;
if ((temp=tree.searchNode(id))!=NULL)
{
cout << temp.getEmpName() << endl;
}
else{
cout<<"ID not found"<<endl;
}
cout << "Would you like to search for an employee?\n";
cout << "Enter Y for yes or N for No: ";
cin >> again;
}while (again == tolower('Y'));
//New changes...
Made change in declaration of searchNode(T) to searchNode(T &)...In your new code the name of employee found was not set in info thats why when you are trying to print EmpName there was not output...So the change is pass the reference of EmployeeInfo to searchitem(T &)
template
bool BinaryTree::searchNode(T &item)
{
TreeNode *nodePtr = root;
while (nodePtr)
{
if (nodePtr->value == item)
{
item.setEmpName(nodePtr->value.getEmpName());
return true;
}
else if (item < nodePtr->value)
nodePtr = nodePtr->left;
else
nodePtr = nodePtr->right;
}
return false;
}