segmentation core dump - need help

Hey all, I'm trying to get this grades program to work... but I'm getting a segmentation core dump error. I am using g++ as my compiler.

#include <iostream>
#include <string>
#include <math.h>

//Grades
struct Grad{
double Assgn[8];
double Quiz[6];
double Test[2];
double Particip;
};

//Pointer to student names and grades
struct ListStu{
string First, Last;
Grad Grades;
ListStu *Next;
};

void DisplayOptions();

class Stu{
public:
Stu();
~Stu();
void Read();
void AddAsgn();
void AddQuiz();
void AddTest();
void Part();
void Display();
void ShowStudent();
double Calculate(ListStu *Rov);
double AsgnAvg(ListStu *Rov);
double QuizAvg(ListStu *Rov);
double TestAvg(ListStu *Rov);
void Show(ListStu *Rov);
void SortQuiz(ListStu *Rov);
void SwapQuiz(int a, int b, ListStu *rov);
void SortNames();
private:
ListStu *Front;
int qcnt, tcnt, acnt, count;
};

void main(){
char input;
Stu Students;
Students.Read();
Students.SortNames();
DisplayOptions();
cin>>input;
while(input!='x')
{
switch(input)
{
case 'a': Students.AddAsgn();
break;
case 'q': Students.AddQuiz();
break;
case 't': Students.AddTest();
break;
case 'p': Students.Part();
break;
case 'd': Students.Display();
break;
case 's': Students.ShowStudent();
break;
case 'x': break;
default: cout<<"Invalid input. Retry."<<endl;
}
DisplayOptions();
cin>>input;
}cout<<"Goodbye."<<endl;
}

Stu::Stu(){
Front=new ListStu;
Front->Next=0;
Front->Grades.Quiz[0]=0;
Front->Grades.Test[0]=0;
Front->Grades.Assgn[0]=0;
tcnt=qcnt=acnt=count=0;
}

Stu::~Stu(){
}

//Takes in Student Names
void Stu::Read(){
string f, l;
ListStu *P, *Tmp;
Tmp=Front;
cout<<"Enter in student names (press quit when ready to continue):"<<endl;
cin>>f;
while(f!="quit"){
cin>>l;
P=new ListStu;
P->First=f;
P->Last=l;
P->Next=0;
Tmp->Next=P;
Tmp=P;
cin>>f;
count++;
cout<<P->First<<P->Last<<endl;
}
P->Next=0;
}

void Stu::AddAsgn(){
int cnt=0;
ListStu *rov;
rov=Front;
cout<<"Enter in Assignment Grades "<<count<<" students."<<endl<<endl;
do{
cnt++;
cout<<cnt<<endl;
cin>>rov->Grades.Assgn[acnt];
rov=rov->Next;
}
while(rov->Next!=0);{
acnt++;}
}

void Stu::AddQuiz(){
ListStu *rov;
rov=Front;
cout<<"Enter in Quiz Grades "<<count<< "students."<<endl<<endl;
for(rov;rov->Next!=0;rov=rov->Next){
cin>>rov->Grades.Quiz[qcnt];
}
qcnt++;
}

void Stu::AddTest(){
ListStu *rov;
rov=Front;
cout<<"Enter in Test Grades "<<count<< "students."<<endl<<endl;
for(rov; rov->Next!=0;rov=rov->Next){
cin>>rov->Grades.Quiz[tcnt];
}
tcnt++;
}
void Stu::Part(){
cout<<"Input Student Name: ";
string l, f;
ListStu *fnd, *rov;
rov=Front;
bool foun=false;
cin>>f;
cin>>l;
while(rov->Next!=0){
if(rov->Last==l && rov->First==f){
fnd=rov;
foun=true;
}
rov=rov->Next;
}
if(foun){
cout<<"Input new participation grade: ";
cin>>fnd->Grades.Particip;
}
else{
cout<<"Name Not Found."<<endl;
}
}

void Stu::Display(){
ListStu *rov;
rov=Front;
for(rov;rov->Next!=0;rov=rov->Next){
Show(rov);
}
cout<<endl;
}

void Stu::ShowStudent(){
string f, l;
cout<<"Input Name: ";
cin>>f;
ListStu *fnd, *rov;
rov=Front;
bool foun=false;
cin>>l;
for(rov;rov->Next!=0;rov=fnd->Next){
if(rov->Last==l && rov->First==f){
fnd=rov;
foun=true;
}
}
if(foun){
Show(fnd);
}
else{
cout<<"Name Not Found."<<endl;
}
}

void Stu::Show(ListStu *Rov){
ListStu *rov=Rov;
cout<<rov->Last<<","<<rov->First<<endl;
cout<<"Assignments: ";
for(int x=0; x<acnt; x++){
cout<<rov->Grades.Assgn[x]<<" ";
}
cout<<"- Ave: "<<AsgnAvg(Rov)<<endl;
cout<<"Quizzes: ";
for(int x=0; x<qcnt; x++){
cout<<rov->Grades.Quiz[x]<<" ";
}
cout<<"- Ave: "<<QuizAvg(Rov)<<endl;
cout<<"Tests: ";
for(int x=0; x<tcnt; x++){
cout<<rov->Grades.Test[x]<<" ";
}
cout<<"- Ave: "<<TestAvg(Rov)<<endl;
cout<<"Class Participation: "<<rov->Grades.Particip<<endl;
cout<<"Total Average: "<<Calculate(rov)<<endl<<endl;
}

double Stu::AsgnAvg(ListStu *Rov){
double tmp;
if(acnt!=0){
for(int x=0; x<acnt; x++){
tmp+=Rov->Grades.Assgn[x];
}
tmp=tmp/acnt;
return tmp;
}
else
return 100;
}

double Stu::QuizAvg(ListStu *Rov){
double tmp;
SortQuiz(Rov);
if(qcnt!=0 && qcnt!=1)
{
for(int x=0; x<qcnt-1; x++){
tmp+=Rov->Grades.Quiz[x];
}
tmp=tmp/(qcnt-1);
return tmp;
}
else
if(qcnt=0)
return 100;
else
return Rov->Grades.Quiz[0];
}

double Stu::TestAvg(ListStu *Rov){
double tmp;
if(tcnt!=0){
for(int x=0; x<tcnt; x++){
tmp+=Rov->Grades.Test[x];
}
tmp=tmp/tcnt;
return tmp;
}
else
return 100;
}

double Stu::Calculate(ListStu *Rov){
double qavg, tavg, aavg, avg;
qavg=tavg=aavg=avg=0;
aavg=AsgnAvg(Rov);
qavg=QuizAvg(Rov);
tavg=TestAvg(Rov);
avg=((aavg*0.5)+(qavg*0.1)+(tavg*0.3)+(Rov->Grades.Particip*0.1));
return avg;
}

void Stu::SortQuiz(ListStu *rov){
for(int x=0;x<qcnt;x++){
if(rov->Grades.Quiz[x]<rov->Grades.Quiz[qcnt-1])
SwapQuiz(x, qcnt-1, rov);
}
}

void Stu::SwapQuiz(int A, int B, ListStu *rov){
double tmp=rov->Grades.Quiz[A];
rov->Grades.Quiz[A]=rov->Grades.Quiz[B];
rov->Grades.Quiz[B]=tmp;
}

void Stu::SortNames(){
ListStu *f, *trav1, *trav2, *sm, *bsm, *l;
f=sm=bsm=l=trav1=trav2=Front;
bool FNT=true;
while(f->Next!=0){
trav1=sm=f->Next;
trav2=bsm=f;
while(trav1->Next!=0){
trav2=trav1;
trav1=trav1->Next;
if(trav1->Last<sm->Last){
sm=trav1;
bsm=trav2;
}
}
if(sm->Next==0){
bsm->Next=0;
sm->Next=f->Next;
f->Next=sm;
f=sm;
}
else{
if(sm==f)
f=sm;
else{
bsm->Next=sm->Next;
sm->Next=f->Next;
f->Next=sm;
f=sm;
}
}
}
if(FNT){
Front=sm;
FNT=false;
}
}

void DisplayOptions(){
cout<<"Select An Option:"<<endl;
cout<<"a: add assignment grade"<<endl;
cout<<"q: add quiz grade"<<endl;
cout<<"t: add test grade"<<endl;
cout<<"p: change participation grade"<<endl;
cout<<"d: display class data"<<endl;
cout<<"s: print student data"<<endl;
cout<<"x: exit"<<endl;
}

Thanks.

When writing code it helps to be a bit of sleuth. In cases like this I start commenting out chunks of code until I am able to compile what's left. Usually the problem can then be found in the last section commented out. By commenting out that section, line by line I can usually get it down to which line the problem appears to be. Then I can access a text book or ask a specific question with pertinent code on a bbs without overworking the people I am asking help from.