Binary Tree insert function not working correctly C++ - c++

Question

I'm working on a program that uses a binary tree. The program reads from a text file, storing each word in a binary tree alphabetically and finds how many times the word appeared in the file.
The problem I'm having is that my insert function is not working (the program crashes when attempting to run it). I don't know what's exactly wrong, but I suspect it has to do with my else statement towards the end of the function that deals with the right side of the tree.
Any help with fixing it would be appreciated.
Header File
#include <iostream>
#include <string>
using namespace std;
#ifndef TREE_H
#define TREE_H
class Tree
{
public:
Tree();
Tree(string str);
void traversal (Tree *);
void read_file();
void insert(string str);
~Tree();
private:
Tree *left;
Tree *right;
string word;
int count;
};
#endif // TREE_H
Cpp File
#include <iostream>
#include <string>
#include <fstream>
#include "tree.h"
using namespace std;
Tree::Tree()
{
left = NULL;
right = NULL;
count = 0;
}
Tree::Tree(string s)
{
word = s;
}
Tree::~Tree() { }
void Tree::read_file()
{
ifstream myfile;
myfile.open("input.txt", ios::out | ios::in | ios::binary);
if(myfile.is_open()){
while(myfile.good()) {
string buffer;
while(true) {
char c = myfile.get();
if(c == '-' || c == '\'' || isalpha(c) ){
if(isupper(c)) c = tolower(c);
buffer+=c;
}
else break;
}
if(buffer.length() >= 4){
insert(buffer);
}
}
myfile.close();
traversal(this);
}
else { cout << "Unable to open file!" << endl; }
}
void Tree::insert(string str) {
if(str.empty()){ // Also I'm debating whether I need this or not since the string
// cannot possibly be empty as it's part of the condition before
//insert is even called.
this->word = str;
count++;
}
else if(this->word == str) count++;
else if(str < this->word){
if(this->left == NULL) this->left = new Tree(str);
else this->left->insert(str);
}
else {
if(this->right == NULL) this->right = new Tree(str);
else this->right->insert(str);
}
}
void Tree::traversal(Tree *T) {
if(T != NULL) {
traversal(T->left);
cout << T->word << " (" << count << ")" << endl;
traversal(T->right);
}
}
Main
#include <iostream>
#include "tree.h"
using namespace std;
int main()
{
Tree tree;
tree.read_file();
return 0;
}

Answer 1

the problem is that you have 2 constructors, and the second one doesn't initialize pointers left/right to NULL.
edit you are showing properties from different objects: use
cout << T->word << " (" << T->count << ")" << endl;
since the recursive procedure doesn't works calling the member function of the received T. You could do it static, or change it
void Tree::traversal() {
if(this) {
traversal(left);
cout << word << " (" << count << ")" << endl;
traversal(right);
}
}
Personally, I do prefer this last 'style'.

Answer 2

Tree::Tree()
{
word.clear();
left = NULL;
right = NULL;
count = 0;
}
Tree::Tree(string s)
{
word = s;
left = NULL;
right = NULL;
count = 0;
}