Need help resolving an Unhandled Exception Error - c++

Question

I've been learning to program for a few months now and I've been working on a program to manage student data. Here's the code:
#include <iostream>
#include <iomanip>
#include <string>
#include <fstream>
#include <stdio.h>
using namespace std;
class Student
{
private:
string name;
string course;
int section;
int grade;
public:
void calcgrade();
void getData();
void showData();
};
void Student::calcgrade()
{
if (grade >= 90)
grade = 'A';
else if (grade >= 80)
grade = 'B';
else if (grade >= 70)
grade = 'C';
else if (grade >= 60)
grade = 'D';
else
grade = 'F';
}
void Student::getData()
{
cout << "Enter the name of the student: ";
cin.ignore();
getline(cin, name);
cout << "Enter the course: ";
cin >> course;
cout << "Enter the section: ";
cin >> section;
cout << "Enter the grade received: ";
cin >> grade;
calcgrade();
}
void Student::showData()
{
cout << ".......Student Information......" << endl;
cout << "Student Name: " << name << endl;
cout << "Course: " << course << endl;
cout << "Section: " << section << endl;
cout << "Grade: " << grade << endl;
cout << endl;
}
void addData()
{
Student st;
ofstream fout;
fout.open("Student.data", ios::binary | ios::out |
ios::app);
st.getData();
fout.write((char*)& st, sizeof(st));
fout.close();
cout << "Data Successfully Saved to File." << endl;
}
void displayData()
{
Student st;
ifstream file;
file.open("Student.data", ios::in | ios::binary);
if (file.is_open())
{
while (file.read((char*)& st, sizeof(st)))
{
st.showData();
}
cout << "Finished Reading Data From File." <<
endl;
}
else
{
cout << "Unable to open file" << endl;
}
file.close();
}
void searchData()
{
Student st;
ifstream file;
file.open("Student.data", ios::in | ios::binary);
string search;
cout << "Please enter the first name of a student to search for: ";
cin >> search;
bool isFound = 0;
while (file.read((char*)& st, sizeof(st)))
{
string temp = " ";
getline(file, temp);
for (int i = 0; i < search.size(); i++)
{
if (temp[i] == search[i])
isFound = 1;
else
{
isFound = 0;
break;
}
}
if (isFound)
{
cout << "The name " << search << " was found in the database." << endl;
break;
}
}
if (file.read((char*)& st, sizeof(st)) && (!isFound))
{
cout << "Name not found." << endl;
}
file.close();
}
void modifyData()
{
Student st;
string stname;
bool isFound = 0;
int pos;
fstream file;
file.open("Student.data", ios::in | ios::out | ios::binary);
cout << "Enter the name of a student whose data you want to modify: ";
cin >> stname;
while (file.read((char*)& st, sizeof(st)))
{
string temp = " ";
getline(file, temp);
for (int i = 0; i < stname.size(); i++)
{
if (temp[i] == stname[i])
isFound = 1;
else
{
isFound = 0;
break;
}
}
if (isFound)
{
pos = file.tellg();
cout << "Current Data" << endl;
st.showData();
cout << "Modified Data" << endl;
st.getData();
file.seekg(pos - sizeof(st));
file.write((char*)& st, sizeof(st));
}
}
if (file.read((char*)& st, sizeof(st)) && (!isFound))
{
cout << "Name not found." << endl;
}
file.close();
}
void deleteData()
{
Student st;
string stname;
bool isFound = 0;
ifstream file;
ofstream fout;
file.open("Student.data", ios::in | ios::binary);
fout.open("Temporary.data", ios::out | ios::app | ios::binary);
cout << "Enter the name of a student whose data you want to delete: ";
cin >> stname;
while (file.read((char*)& st, sizeof(st)))
{
string temp = " ";
getline(file, temp);
for (int i = 0; i < stname.size(); i++)
{
if (temp[i] == stname[i])
isFound = 1;
else
{
isFound = 0;
break;
}
}
if (isFound)
{
cout << "Bleh" << endl;
fout.write((char*)& st, sizeof(st));
}
}
if (file.read((char*)& st, sizeof(st)) && (!isFound))
{
cout << "Name not found." << endl;
}
fout.close();
file.close();
remove("Student.data");
rename("Temporary.data", "Student.data");
}
void printData()
{
ifstream file;
file.open("Student.data", ios::in | ios::binary);
if (file.is_open())
{
cout << file.rdbuf();
}
file.close();
}
int main()
{
int num;
do
{
cout << "...............STUDENT MANAGEMENT SYSTEM..............\n";
cout << "======================================== ==============\n";
cout << "0. Close Program. " << endl;
cout << "1. Add Data. " << endl;
cout << "2. List Data. " << endl;
cout << "3. Modify Data. " << endl;
cout << "4. Search For Data. " << endl;
cout << "5. Print Data. " << endl;
cout << "6. Delete Data. " << endl;
cout << "Choose an option: ";
cin >> num;
if (num == 1)
{
addData();
}
else if (num == 2)
{
displayData();
}
else if (num == 3)
{
modifyData();
}
else if (num == 4)
{
searchData();
}
else if (num == 5)
{
printData();
}
else if (num == 6)
{
deleteData();
}
} while (num > 0);
return 0;
}
Ideally, when the program runs, the user chooses an option, with different function calls depending on the number entered. The Add Data option works fine, but when choosing others, such as List Data or Search Data, I run into an error such as: Unhandled exception thrown: read access violation. _Pnext was 0x10A6A04.
Code in xmemory:
inline void _Container_base12::_Orphan_all() noexcept {
#if _ITERATOR_DEBUG_LEVEL == 2
if (_Myproxy != nullptr) { // proxy allocated, drain it
_Lockit _Lock(_LOCK_DEBUG);
for (_Iterator_base12** _Pnext = &_Myproxy->_Myfirstiter; *_Pnext != nullptr;
*_Pnext = (*_Pnext)->_Mynextiter) {
(*_Pnext)->_Myproxy = nullptr;
}
_Myproxy->_Myfirstiter = nullptr;
}
Given there are no obvious errors in the code, I'd like a little help in figuring out what I've done wrong.