A ton of undefined reference errors - c++

Question

I don't know if I'm linking wrong but I'm compiling this on linux and I'm getting a LOT of undefined references for my node functions. I'm writing a binary search tree to searches for telephones for class that is due tonight.
bst.cpp
#include "bst.hpp"
BST::BST(void)
{
count = 0;
root = NULL;
}
void BST::insert(long long x, string y)
{
Node *newnode = new Node(x, y);
Node *temp;
if (count == 0)
{
root = newnode;
count++;
}
else
{
while(temp->getleft() != NULL && temp->getright() != NULL)
{
if(newnode->getnum() < temp->getnum())
{
temp = temp->getleft();
}
else
{
temp = temp->getright();
}
}
if (newnode->getnum() < temp->getnum())
{
temp->setleft(newnode);
}
else
{
temp->setright(newnode);
}
}
}
Node * BST::getroot(void)
{
return root;
}
Node* BST::delete_node(Node *troot, long long key)
{
if (count == 0)
{
return troot;
}
else if(key < troot->getnum())
{
delete_node(troot->getleft(), key);
}
else if (key > troot->getnum())
{
delete_node(troot->getright(), key);
}
else
{
if(troot->getleft() == NULL && troot->getright() == NULL)
{
delete troot;
troot == NULL;
}
else if(troot->getright() == NULL)
{
Node *temp = troot;
troot = troot->getleft();
delete temp;
}
else if(troot->getleft() == NULL)
{
Node *temp = troot;
troot = troot->getright();
delete temp;
}
}
return troot;
}
void BST::preverse(Node* troot)
{
if(root == NULL)
{
cout << "The tree is empty\n";
}
if(troot == NULL)
{
return;
}
cout << troot->getname() << endl;
cout << troot->getnum() << endl;
preverse(troot->getleft());
preverse(troot->getright());
}
void BST::postverse(Node* troot)
{
if(root == NULL)
{
cout << "The tree is empty\n";
}
if(troot == NULL)
{
return;
}
postverse(troot->getleft());
postverse(troot->getright());
cout << troot->getname() << endl;
cout << troot->getnum() << endl;
}
void BST::inverse(Node* troot)
{
if(root == NULL)
{
cout << "The tree is empty\n";
}
if(troot == NULL)
{
return;
}
inverse(troot->getleft());
cout << troot->getname() << endl;
cout << troot->getnum() << endl;
inverse(troot->getright());
}
void BST::search(Node* troot, long long key)
{
if(root == NULL)
{
cout << "The tree is empty\n";
}
if(troot == NULL)
{
return;
}
if(key == troot->getnum())
{
cout << troot->getname();
}
search(troot->getleft(), key);
search(troot->getright(), key);
}
bst.hpp
#include "node.hpp"
#ifndef bst_hpp
#define bst_hpp
class BST
{
Node* root;
long long count;
public:
BST(void);
void insert(long long x, string y);
Node* getroot(void);
Node* delete_node(Node* troot, long long key);
void preverse(Node* troot);
void postverse(Node* troot);
void inverse(Node* troot);
void search(Node* troot, long long key);
};
#endif
node.cpp
#include "node.hpp"
Node::Node(void)
{
number = 0;
name = "no name";
left = NULL;
right = NULL;
}
Node::Node(long long t, string n)
{
number = t;
name = n;
left = NULL;
right = NULL;
}
Node * Node::getleft(void)
{
return left;
}
Node * Node::getright(void)
{
return right;
}
void Node::setleft(Node * ptr)
{
left = ptr;
}
void Node::setright(Node * ptr)
{
right = ptr;
}
long long Node::getnum(void)
{
return number;
}
string Node::getname(void)
{
return name;
}
node.hpp
#ifndef node_hpp
#define node_hpp
#include <string>
#include <iostream>
using namespace std;
class Node
{
long long number;
string name;
Node *left;
Node *right;
public:
Node(void);
Node(long long t, string n);
Node* getleft(void);
Node* getright(void);
void setleft(Node* ptr);
void setright(Node* ptr);
long long getnum(void);
string getname(void);
};
#endif
main.cpp
#include "bst.hpp"
using namespace std;
int main(void)
{
int choice;
long long numin;
string input;
BST phbook;
do
{
cout << "1. Insert a name and number.\n2. Delete using number.\n3. Traverse pre-order\n4. Traverse post-order\n";
cout << "5. Traverse in-order\n6. Search using number.\n6. Exit program\n";
switch(choice)
{
case 1:
cout << "Enter a name\n";
cin.ignore();
getline(cin, input);
cout << "Enter a number\n";
cin >> numin;
phbook.insert(numin, input);
break;
case 2:
cout << "Enter the phone number you'd like to delete.\n";
cin >> numin;
phbook.delete_node(phbook.getroot(), numin);
break;
case 3:
phbook.preverse(phbook.getroot());
break;
case 4:
phbook.postverse(phbook.getroot());
break;
case 5:
phbook.inverse(phbook.getroot());
break;
case 6:
cout << "Enter a phone number to search.\n";
cin >> numin;
phbook.search(phbook.getroot(),numin);
default:
numin=numin;
}
}while(choice >= 1 && choice <= 6);
return 0;
}
To me, nothing looks wrong in linking the files.
Some examples : undefined reference to Node::getnum()
undefined reference to Node::getname()

Answer 1

Check the order of compiled elements:
g++ node.cpp -o node.o bst.cpp -o bst.o main.cpp -o main.o
Result:
./main.o
1. Insert a name and number.
2. Delete using number.
3. Traverse pre-order
4. Traverse post-order
5. Traverse in-order
6. Search using number.
6. Exit program