Im getting undefined reference errors for my main when running make. Help?

main.o: In function `main':

main.cpp:(.text+0x2a): undefined reference to `Stack::Stack()'

main.cpp:(.text+0x3e): undefined reference to `Stack::push(int)'

main.cpp:(.text+0x52): undefined reference to `Stack::push(int)'

main.cpp:(.text+0x66): undefined reference to `Stack::push(int)'

main.cpp:(.text+0x7a): undefined reference to `Stack::push(int)'

main.cpp:(.text+0x8e): undefined reference to `Stack::push(int)'

main.cpp:(.text+0xb3): undefined reference to `Stack::top()'

main.cpp:(.text+0xfb): undefined reference to `std::ostream& operator<< (std::ostream&, Stack&)'

main.cpp:(.text+0x10a): undefined reference to `Stack::pop()'

main.cpp:(.text+0x133): undefined reference to `std::ostream& operator<< (std::ostream&, Stack&)'

main.cpp:(.text+0x142): undefined reference to `Stack::Stack()'

main.cpp:(.text+0x319): undefined reference to `Stack::push(Student)'

main.cpp:(.text+0x35e): undefined reference to `Stack::push(Student)'

main.cpp:(.text+0x3a3): undefined reference to `Stack::push(Student)'

main.cpp:(.text+0x3cb): undefined reference to `Stack::top()'

main.cpp:(.text+0x424): undefined reference to `Stack::pop()'

main.cpp:(.text+0x433): undefined reference to `Stack::isEmpty()'

main.cpp:(.text+0x453): undefined reference to `Stack::top()'

main.cpp:(.text+0x48a): undefined reference to `Stack::pop()'

main.cpp:(.text+0x4e1): undefined reference to `Stack::~Stack()'

main.cpp:(.text+0x4f0): undefined reference to `Stack::~Stack()'

main.cpp:(.text+0x66d): undefined reference to `Stack::~Stack()'

main.cpp:(.text+0x681): undefined reference to `Stack::~Stack()'

///////////Student.h file

#pragma once

#ifndef STUDENT_H

#define STUDENT_H

#include

#include

#include

using namespace std;

class Student {

private:

float gpa;

string ssn;

public:

Student();

void setGPA(float v);

void setSSN(string s);

void print();

class OutOfGPARange { }; // empty inner class definition under public

class InvalidSSN { }; // empty inner class definition under public

};

#endif

///////////////Student.cpp file

#include

#include

#include "Student.h"

Student::Student()

{

gpa = 0;

ssn = "";

}

void Student::setGPA(float g) {

//assert(g >= 0.0 && g <= 4.0);

//create an instance of the OutOfGPARange class, called exception

if (g < 0.0 || g > 4.0) throw OutOfGPARange();

gpa = g;

}

void Student::setSSN(string s) {

const int SSN_LENGTH = 9;

if (s.length() != SSN_LENGTH)

throw InvalidSSN();

//Checking each character is a digit should be here

//Otherwise, throw InvalidSSN();

ssn = s;

}

void Student::print() {

cout << "gpa: " << gpa << endl;

cout << "ssn: " << ssn << endl;

}

///////////////Stack.h file

#pragma once

#include

#include

#include

using namespace std;

template

class Stack

{

struct Node

{

T data;

Node *next;

};

Node *head;

public:

Stack();

~Stack();

void push(T data);

T top();

void pop();

template

friend ostream& operator<<(ostream &out, Stack &data);

bool isEmpty();

};

///////////////Stack.cpp file

#include "Stack.h"

template

Stack::Stack()

{

head = NULL;

}

template

Stack::~Stack()

{

Node *cur = head, *tmp;

while (cur != NULL)

{

tmp = cur->next;

delete cur;

cur = tmp;

}

}

template

void Stack::push(T data)

{

Node *cur = head, *newNode;

newNode = new Node;

newNode->data = data;

newNode->next = NULL;

if (head == NULL)

{

head = newNode;

}

else

{

newNode->next = head;

head = newNode;

}

}

template

T Stack::top()

{

return head->data;

}

template

void Stack::pop()

{

Node *tmp = head;

head = head->next;

delete tmp;

}

template

ostream& operator<<(ostream &out, Stack &data)

{

typename Stack::Node *cur = data.head;

while (cur != NULL)

{

out << cur->data << " ";

cur = cur->next;

}

return out;

}

template

bool Stack::isEmpty()

{

if (head == NULL)

return true;

return false;

}

////////////////Main.cpp file

#include

#include

#include"Stack.h"

#include"Student.h"

using namespace std;

int main() {

//declare stack of int type

Stack intStack;

intStack.push(5);

intStack.push(4);

intStack.push(3);

intStack.push(2);

intStack.push(1);

cout << "Top of intStack is : " << intStack.top() << endl;

cout << "intStack items are : ";

cout << intStack;

intStack.pop();

cout << " intStack items after one pop operation: ";

cout << intStack;

//now declare Stack of type Student

Stack StudentStack;

Student st[5];

st[0].setGPA(3.5);

st[0].setSSN("111111111");

st[1].setGPA(3.5);

st[1].setSSN("222222222");

st[2].setGPA(3.5);

st[2].setSSN("333333333");

//push some students onto stack

StudentStack.push(st[0]);

StudentStack.push(st[1]);

StudentStack.push(st[2]);

Student pt = StudentStack.top();

cout << "Top of the stack is : " << endl;

pt.print();

cout << "Print stack after one pop operation: ";

StudentStack.pop();

while (!StudentStack.isEmpty())

{

pt = StudentStack.top();

StudentStack.pop();

pt.print();

}

}

/////////////////Makefile

#

a.out: Student.o Stack.o main.o

g++ Student.o Stack.o main.o

Student.o: Student.h Student.cpp

g++ -c Student.cpp

Stack.o: Student.h Stack.h Stack.cpp

g++ -c Stack.cpp

main.o: Student.h Stack.h main.cpp

g++ -c main.cpp

clean:

rm a.out *.o