Determine the height of a binary tree - height

Question

I have written a code to create and display a binary tree. This program worked and satisfied the requirements of the course I was on, however afterwards I attempted to add to the working program to find the height of the tree and so far with no luck. I have looked at many examples and none of the additions or changes I have made to my program made it work.
#include <cstdlib>
#include <iostream>
#include <cstdio>
using namespace std;
class TreeNode
{ public:
TreeNode *pLeft;
int data;
TreeNode *pRight;
TreeNode *leftHeight;
TreeNode *rightHeight;
TreeNode(int num)
{
data = num;
pLeft = NULL;
pRight = NULL;
}
}; ////////////////////////////////////////////
class Binary_Tree
{ private:
//int getHeight;
public:
TreeNode *rootPtr;
Binary_Tree()
{ rootPtr = NULL;
}
/* ---------------------------------- */
void Insert(int value)
{
TreeNode *pNewNode = new TreeNode(value);
TreeNode *pCurrent;
TreeNode *pPrevious;
pPrevious = NULL;
pCurrent = rootPtr;
while(pCurrent != NULL)
{ pPrevious = pCurrent;
if (value < (pPrevious -> data))
pCurrent = pCurrent -> pLeft;
else
pCurrent = pCurrent -> pRight;
}
if(pPrevious == NULL)
{ rootPtr = pNewNode;
}
else
{ if (value < (pPrevious -> data))
{ pPrevious -> pLeft = pNewNode;
pNewNode -> pLeft = pCurrent;
}
else
{ pPrevious -> pRight = pNewNode;
pNewNode -> pRight = pCurrent;
}
}
}
/* ------------------------------------------- */
int getHeight(TreeNode *TreePtr)
{
if( TreePtr == NULL)
{
return(0);
}
else
{
leftHeight = getHeight(r->pLeft);
rightHeight = getHeight(r->pRight);
if(leftHeight > rightHeight)
{
return(leftHeight + 1);
}
else
{
return(rightHeight + 1);
}
}
}
/* ------------------------------------------- */
void Display(TreeNode *TreePtr, int count)
{
if(TreePtr !=NULL)
{
count++;
Display(TreePtr -> pRight, count);
for(int i = i; i < count; i++)
{
printf(" ");
}
printf("%d \n", TreePtr -> data);
Display(TreePtr -> pLeft, count);
}
}//////////////////////end display //////////////////////
void DisplayInOrder(TreeNode *TreePtr)
{
if(TreePtr != NULL)
{
DisplayInOrder(TreePtr -> pLeft);
cout << TreePtr -> data << endl;
DisplayInOrder(TreePtr -> pRight);
}
}
};
/* -------------------------------------- */
/////////////////////////////////////////////////////////////
int main()
{ int number[8] = {7, 9, 3, 2, 12, 5, 8};
Binary_Tree Tree;
for (int i = 0; i <8; i++)
{
cout << "data inserted = "<< number[i] << endl;
Tree.Insert(number[i]);
}
cout << endl << "Display Tree" << endl << endl;
Tree.Display(Tree.rootPtr, 0);
cout << endl;
cout << endl << "tree height" << endl << endl;
getHeight(root);
cout << endl;
Tree.DisplayInOrder(Tree.rootPtr);
system("PAUSE");
return EXIT_SUCCESS;
}

Answer 1

There were compilation problems. After fixing them it seems to print the height. Note the "final height" line with the value 4
#include <cstdlib>
#include <iostream>
#include <cstdio>
using namespace std;
class TreeNode
{ public:
TreeNode *pLeft;
int data;
TreeNode *pRight;
TreeNode *leftHeight;
TreeNode *rightHeight;
TreeNode(int num)
{
data = num;
pLeft = NULL;
pRight = NULL;
}
}; ////////////////////////////////////////////
class Binary_Tree
{ private:
//int getHeight;
public:
TreeNode *rootPtr;
Binary_Tree()
{ rootPtr = NULL;
}
/* ---------------------------------- */
void Insert(int value)
{
TreeNode *pNewNode = new TreeNode(value);
TreeNode *pCurrent;
TreeNode *pPrevious;
pPrevious = NULL;
pCurrent = rootPtr;
while(pCurrent != NULL)
{ pPrevious = pCurrent;
if (value < (pPrevious -> data))
pCurrent = pCurrent -> pLeft;
else
pCurrent = pCurrent -> pRight;
}
if(pPrevious == NULL)
{ rootPtr = pNewNode;
}
else
{ if (value < (pPrevious -> data))
{ pPrevious -> pLeft = pNewNode;
pNewNode -> pLeft = pCurrent;
}
else
{ pPrevious -> pRight = pNewNode;
pNewNode -> pRight = pCurrent;
}
}
}
/* ------------------------------------------- */
int getHeight(TreeNode *TreePtr)
{
if( TreePtr == NULL)
{
return(0);
}
else
{
int leftHeight = getHeight(TreePtr->pLeft);
int rightHeight = getHeight(TreePtr->pRight);
if(leftHeight > rightHeight)
{
return(leftHeight + 1);
}
else
{
return(rightHeight + 1);
}
}
}
/* ------------------------------------------- */
void Display(TreeNode *TreePtr, int count)
{
if(TreePtr !=NULL)
{
count++;
Display(TreePtr -> pRight, count);
for(int i = i; i < count; i++)
{
printf(" ");
}
printf("%d \n", TreePtr -> data);
Display(TreePtr -> pLeft, count);
}
}//////////////////////end display //////////////////////
void DisplayInOrder(TreeNode *TreePtr)
{
if(TreePtr != NULL)
{
DisplayInOrder(TreePtr -> pLeft);
cout << TreePtr -> data << endl;
DisplayInOrder(TreePtr -> pRight);
}
}
};
/* -------------------------------------- */
/////////////////////////////////////////////////////////////
int main()
{ int number[8] = {7, 9, 3, 2, 12, 5, 8};
Binary_Tree Tree;
for (int i = 0; i <8; i++)
{
cout << "data inserted = "<< number[i] << endl;
Tree.Insert(number[i]);
}
cout << endl << "Display Tree" << endl << endl;
Tree.Display(Tree.rootPtr, 0);
cout << endl;
cout << endl << "tree height" << endl << endl;
int height = Tree.getHeight(Tree.rootPtr);
cout << endl;
cout << "final height: " << height << endl;
Tree.DisplayInOrder(Tree.rootPtr);
system("PAUSE");
return EXIT_SUCCESS;
}

Answer 2

you have some errors in your code:
you are using r where it should be TreePtr
you did not declared root, i guess u wanted to use Tree
leftHeight and rightHeight needed to be declared
the declaration of getHeight is inside the class so you need to call Tree.getHeight. btw, this method should not be in the class or should not get a tree node.
here is the fixed code:
#include <cstdlib>
#include <iostream>
#include <cstdio>
using namespace std;
class TreeNode
{ public:
TreeNode *pLeft;
int data;
TreeNode *pRight;
TreeNode *leftHeight;
TreeNode *rightHeight;
TreeNode(int num)
{
data = num;
pLeft = NULL;
pRight = NULL;
}
}; ////////////////////////////////////////////
class Binary_Tree
{ private:
//int getHeight;
public:
TreeNode *rootPtr;
Binary_Tree()
{ rootPtr = NULL;
}
/* ---------------------------------- */
void Insert(int value)
{
TreeNode *pNewNode = new TreeNode(value);
TreeNode *pCurrent;
TreeNode *pPrevious;
pPrevious = NULL;
pCurrent = rootPtr;
while(pCurrent != NULL)
{ pPrevious = pCurrent;
if (value < (pPrevious -> data))
pCurrent = pCurrent -> pLeft;
else
pCurrent = pCurrent -> pRight;
}
if(pPrevious == NULL)
{ rootPtr = pNewNode;
}
else
{ if (value < (pPrevious -> data))
{ pPrevious -> pLeft = pNewNode;
pNewNode -> pLeft = pCurrent;
}
else
{ pPrevious -> pRight = pNewNode;
pNewNode -> pRight = pCurrent;
}
}
}
/* ------------------------------------------- */
int getHeight(TreeNode *TreePtr)
{
if( TreePtr == NULL)
{
return(0);
}
else
{
int leftHeight = getHeight(TreePtr->pLeft);
int rightHeight = getHeight(TreePtr->pRight);
if(leftHeight > rightHeight)
{
return(leftHeight + 1);
}
else
{
return(rightHeight + 1);
}
}
}
/* ------------------------------------------- */
void Display(TreeNode *TreePtr, int count)
{
if(TreePtr !=NULL)
{
count++;
Display(TreePtr -> pRight, count);
for(int i = i; i < count; i++)
{
printf(" ");
}
printf("%d \n", TreePtr -> data);
Display(TreePtr -> pLeft, count);
}
}//////////////////////end display //////////////////////
void DisplayInOrder(TreeNode *TreePtr)
{
if(TreePtr != NULL)
{
DisplayInOrder(TreePtr -> pLeft);
cout << TreePtr -> data << endl;
DisplayInOrder(TreePtr -> pRight);
}
}
};
/* -------------------------------------- */
/////////////////////////////////////////////////////////////
int main()
{ int number[8] = {7, 9, 3, 2, 12, 5, 8};
Binary_Tree Tree;
for (int i = 0; i <8; i++)
{
cout << "data inserted = "<< number[i] << endl;
Tree.Insert(number[i]);
}
cout << endl << "Display Tree" << endl << endl;
Tree.Display(Tree.rootPtr, 0);
cout << endl;
cout << endl << "tree height" << endl << endl;
cout << Tree.getHeight(Tree.rootPtr) << endl;
cout << endl;
Tree.DisplayInOrder(Tree.rootPtr);
system("PAUSE");
return EXIT_SUCCESS;
}