Symbol referencing errors?

Hi,

Newbie here, trying to compile with g++ and getting these errors:

Undefined first referenced
symbol in file
typeinfo for Student student.o
vtable for Student student.o
ld: fatal: Symbol referencing errors. No output written to student

I've seen people posting this problem all over the web but haven't found anything that I can understand! Here's my header file:

Code:

#include <iostream>
#include <fstream>
using namespace std;

class Student
{
public:
        virtual void Print(ostream& os);
        virtual double Average(){};
        Student(){};
        virtual char GetSubject(){};
protected:
        Student(char* first, char* last, char sub);
        char firstName[21];
        char lastName[21];
        char subject;
};

class English : public Student
{
public:
        English(char* first, char* last, char sub, int atten, int proj, int mid, int final);
        double Average();
        char GetSubject();
        void Print(ostream& os);
private:
        int attendance;
        int project;
        int midterm;
        int finalExam;
};

class History : public Student
{
public:
        History(char* first, char* last, char sub, int p, int mid, int final);
        double Average();
        char GetSubject();
        void Print(ostream& os);
private:
        int paper;
        int midterm;
        int finalExam;
};

class Math : public Student
{
public:
        Math(char* first, char* last, char sub, int q1, int q2, int q3, int q4, int q5, int t1, int t2, int final); 
        double Average();
        char GetSubject();
        void Print(ostream& os);
private:
        double quizAvg;
        int test1;
        int test2;
        int finalExam;
};

... my definitions:

Code:

#include <iostream>
#include <cstring>
#include <fstream>
#include "student.h"

using namespace std;

Student::Student(char* first, char* last, char sub)
{
    strcpy(firstName, first);
    strcpy(lastName, last);
    subject = sub;
}

English::English(char* first, char* last, char sub, int atten, int proj, int mid, int final):
        Student(first, last, sub)
{
    attendance = atten;
    project = proj;
    midterm = mid;
    finalExam = final;
}

char English::GetSubject()
{

}

void English::Print(ostream& os)
{
    char* fullName = strcat(firstName, " ");
    fullName = strcat(fullName, lastName);
    os.width(42);
    os << fullName;
    os.width(8);
    os << finalExam;
    os.width(8);
    os << Average();
    switch (static_cast<int>(Average()) / 10)
    {
        case 10:
        case 9:
            os << 'A';
            break;
        case 8:
            os << 'B';
            break;
        case 7:
            os << 'C';
            break;
        case 6:
            os << 'D';
            break;   
        default:    
            os << 'E';
    }
    os << '\n';  
}

double English::Average()
{
    return static_cast<double>(attendance + project*3 + midterm*3 + finalExam*3)/1000;
}

History::History(char* first, char* last, char sub, int p, int mid, int final):
        Student(first, last, sub)
{
    paper = p;
    midterm = mid;
    finalExam = final;
}

char History::GetSubject()
{

}

void History::Print(ostream& os)
{
    char* fullName = strcat(firstName, " ");
    fullName = strcat(fullName, lastName);
    os.width(42);
    os << fullName;
    os.width(8);
    os << finalExam;
    os.width(8);
    os << Average();
    switch (static_cast<int>(Average()) / 10)
    {
        case 10:
        case 9:
            os << 'A';
            break;
        case 8:
            os << 'B';
            break;
        case 7:
            os << 'C';
            break;
        case 6:
            os << 'D';
            break;   
        default:    
            os << 'E';
    }
    os << '\n';  
}

double History::Average()
{
    return static_cast<double>(paper*25 + midterm*35 + finalExam*40)/10000;
}

Math::Math(char* first, char* last, char sub, int q1, int q2, int q3, int q4, int q5, int t1, int t2, int final):
        Student(first, last, sub)
{
    quizAvg = (q1, q2, q3, q4, q5)/5;    
    test1 = t1;
    test2 = t2;
    finalExam = final;
}

char Math::GetSubject()
{

}

void Math::Print(ostream& os)
{
    char* fullName = strcat(firstName, " ");
    fullName = strcat(fullName, lastName);
    os.width(42);
    os << fullName;
    os.width(8);
    os << finalExam;
    os.width(8);
    os << Average();
    switch (static_cast<int>(Average())/10)
    {
        case 10:
        case 9:
            os << 'A';
            break;
        case 8:
            os << 'B';
            break;
        case 7:
            os << 'C';
            break;
        case 6:
            os << 'D';
            break;   
        default:    
            os << 'E';
    }
    os << '\n';  
}

double Math::Average()
{
    return static_cast <double>(quizAvg*15 + test1*25 + test2*25 + finalExam*35)/10000;
}

... and just in case it matters, my main file and makefile:

Code:

#include <iostream>
#include <fstream>
#include <cstring>
#include "student.h"

using namespace std;

void PrintHeader(ofstream& os, char sub);

int main()
{
    char first[21], last[21], fullName[42], subject;
    char* inFilename, *outFilename;
    int size, a, b, c, d, e, f, g, h, numE = 0, numH = 0, numM = 0;

    ifstream in1;
    ofstream out1;

    cout << "Please enter the name of the input file.\nFilename: ";
    cin >> inFilename;

    cout << "Please enter the name of the output file.\nFilename: ";
    cin >> outFilename;

    in1.open(inFilename);
    out1.open(outFilename);

    if (!in1)
    {
        cout << "Error: invalid input file name.\n";
        exit(0);
    }

    in1 >> size;        // read first line (size of file)
                        // and declare new list of size
    Student *list = new Student[size];

    for (int i = 0; i < size; i++)
    {
        in1 >> first >> last >> subject;

        if (subject == 'E')
        {
            in1 >> a >> b >> c >> d;
            English e(first, last, subject, a, b, c, d);
            list[i] = e;
            numE++;
        }
        if (subject == 'H')
        {
            in1 >> a >> b >> c;
            History h(first, last, subject, a, b, c);
            list[i] = h;
            numH++;
        }
        if (subject =='M')
        {
            in1 >> a >> b >> c >> d >> e >> g >> h;
            Math m(first, last, subject, a, b, c, d, e, f, g, h);
            list[i] = m;
            numM++;
        }
    }

// print to output file
    out1 << "Student Grade Summary\n---------------------\n\n";

    if (numE != 0)
    {
        PrintHeader(out1, 'E');
        for (int i = 0; i < size; i++)
        {
            if (list[i].GetSubject() == 'E')
                list[i].Print(out1);
        }
    }
    if (numH != 0)
    {
        PrintHeader(out1, 'H');
        for (int i = 0; i < size; i++)
        {
            if (list[i].GetSubject() == 'H')
                list[i].Print(out1);
        } 
    }
    if (numM != 0)
    {
        PrintHeader(out1, 'M');
        for (int i = 0; i < size; i++)
        {
            if (list[i].GetSubject() == 'M')
                list[i].Print(out1);
        } 
    }

    delete[] list;
    in1.close();
    out1.close();

    return 0;
}

void PrintHeader(ofstream& os, char sub)
{
    os << '\n';
    if (sub == 'E')
        os << "ENGLISH CLASS\n\n";
    else if (sub == 'H')
        os << "HISTORY CLASS\n\n";
    else
        os << "MATH CLASS\n\n";
 
    os.width(42);
    os << "Student";
    os.width(8);
    os << "Final";
    os.width(8);
    os << "Final";
    os << "Letter\n";
    os.width(42);
    os << "Name";
    os.width(8);
    os << "Exam";
    os.width(8);
    os << "Avg";
    os << "Grade\n----------------------------------------------------------------\n";

}

Code:

student: student.o main.o
        g++ -o student student.o main.o

student.o: student.cpp student.h
        g++ -c student.cpp

main.o: main.cpp student.h
        g++ -c main.cpp

clean:
        rm -f *.o student

I'd appreciate any help.

Add this code, it's called header guards.

Code:

#ifndef STUDENT_H_INCLUDED
#define STUDENT_H_INCLUDED

// your code here

#endif

I'm going to bed right now and I don't really feel like explaining today (probably tomorrow) but this should let you at least be able to compile your program without errors.

I emailed my professor and he said I just needed to add braces after that virtual function in the base class Student (the one that I missed, apparently). It compiles now. But thanks for the response.

Unless a function is "pure virtual," which your Student's Print function isn't, you need to define it. You should either come up with a simple definition, or just put

Code:

{}

after the declaration like you did with your other virtual functions.
-Crazed

EDIT: oops looks like you and your prof beat me to it