Recursive BST Destructor

[edge6768]

Hey guys,

I'm trying to implement a binary search tree. I'm having an issue with the destructor, which calls another function to kick off the recursive deletion of all nodes.

Compiling with

g++ -std=c++14 -pedantic

on Ubuntu

I'm getting the following error:

/tmp/ccrumI5U.o: In function 'bst::~bst()':
bst.cpp:(.text+0x7c): undefined reference to 'bst::DESTROY(bstNode*)'
collect2: error: ld returned 1 exit status

Below are the destructor and DESTROY functions:
Destructor (public):

bst::~bst() {
	DESTROY(root);
} // END ~bst() 

DESTROY (private):

void DESTROY(bstNode* cur) {
	if(cur != nullptr) {

		if( (cur->left == nullptr) && (cur->right == nullptr) ) {
			delete cur;
			cur = nullptr;
		} else {
			DESTROY(cur->left);
			DESTROY(cur->right);
		} // END if/else

	} // END if

return;
} // END DESTROY(cur) 

Any advice? I have tried moving the DESTROY function to public scope and defining it before the destructor but the error persists...

[jlb]

Where did you implement the DESTROY function, in the class definition or outside the class definition?

[edge6768]

This is the entire source code:

BST.h

#ifndef BST_H
#define BST_H

struct bstNode {
	bstNode* left;
	bstNode* right;
	int data;
};

#include <string>

using std::string;

class bst {
public:
	bst();
	bst(const string& toRead);
	~bst();

	void Read(const string& toRead);
	void Print();
	bool insert(int toAdd);
	int getNodeCount() const;
	
private:
	bstNode* root;
	unsigned nodeCount;
	bool insert(int toAdd, bstNode* cur);
	void Print(bstNode* cur);
	void DESTROY(bstNode* cur);
	

}; // END bst

#endif 

_________________________________________________________________________________

BST.cpp:

#include "bst.h"

#include <fstream>
#include <cassert>

#include <iostream>
using std::cout;

using std::ifstream;

bst::bst() : root(nullptr), nodeCount(0) {

} // END bst()

bst::bst(const string& toRead) : root(nullptr), nodeCount(0) {
	Read(toRead);
} // END bst(toRead)

bst::~bst() {
	DESTROY(root);
} // END ~bst()

void bst::Read(const string& toRead) {
	ifstream fin(toRead);
	assert(fin);

	int temp;
	while(!fin.eof() && (fin >> temp)) {
		insert(temp);
	} // END while(!fin.eof() && (fin >> temp))

} // END Read(toRead)

void bst::Print() {
	Print(root);
} // END Print()

void bst::Print(bstNode* cur) {
	if(cur != nullptr) {
		Print(cur->left);
		cout << cur->data;
		Print(cur->right);
	} // END if
} // END Print(cur)

void DESTROY(bstNode* cur) {
	if(cur != nullptr) {

		if( (cur->left == nullptr) && (cur->right == nullptr) ) {
			delete cur;
			cur = nullptr;
		} else {
			DESTROY(cur->left);
			DESTROY(cur->right);
		} // END if/else

	} // END if

return;
} // END DESTROY(cur)

bool bst::insert(int toAdd) {
	insert(toAdd, root);
} // END insert(toAdd)

bool bst::insert(int toAdd, bstNode* cur) {
	if(cur == nullptr) {
		std::cout << toAdd << '\n';

		cur = new bstNode;
		cur->data = toAdd;

		nodeCount++;
	} else if(toAdd < cur->data) {
		insert(toAdd, cur->left);
	} else {
		insert(toAdd, cur->right);
	} // END if/else

} // END insert(toAdd, cur)

int bst::getNodeCount() const {
	return nodeCount;
} // END getNodeCount() 

I've tried moving the definition/declaration between public/private and before/after the destructors but it doesn't seem to change anything.

[edge6768]

WOW. Missing the scope resolution for the DESTROY function. LIne 46 of bst.cpp should be void bst::DESTROY... instead of void DESTROY... Been looking at this for an hour and a half. *sigh*