Van

#include <fstream>
#include <iostream>
#include <cstdlib>
#include <cstring>
using namespace std;
int main()
{
 string g;
 string e;
 char degree[30];
    char b[30];
    int a;
 string k;
 int c;
 int j;
 float y;
 float w;
 float m;
 int n;
 string d;
 string duser, dpass;
 string inputuser, inputpass;
 string data;
 char newdata[30];
 ifstream infile;
 infile.open("Security.txt");
 getline(infile,data);
 duser = data;
 getline(infile,data);
    dpass = data;

 cout << "Student Information System \n";
  cout << "Login \n";
  cout << "Username: ";
  cin >> inputuser;
  cout << "\nPassword: ";
  cin >> inputpass;
  while (inputuser != duser || inputpass != dpass)
  {
  cout << "Incorrect! Please relogin \n";
  cout << "Username: \n";
  cin >> inputuser;
  cout << "\nPassword: ";
  cin >> inputpass;
  }
  if (inputuser == duser && inputpass == dpass)
  {
   system("pause");
   system("cls");
   cout << "Welcome to Student Information System! \n";
  }
cout << "1. Student Information \n";
cout << "2. Quit \n";
cin >> j;

if (j == 1)
{
 cout << " 1. Add \n";
 cout << " 2. Edit \n";
 cout << "  3. Read \n";
 cout << " 4. Delete Student Data \n";
 cout << " 5. Back to Main Menu \n";
 cin >> c;
 if (c==1)
 {
 cout << "Enter your ID Number: ";
 cin >> k;
 k+= ".txt";
 ofstream addfile;
 addfile.open(k.c_str());
     cout << "Input name: ";
 cin.getline(b,30);
 getline(cin,data);
     addfile << data << endl;
 cout <<"Enter your College Year: ";
     cin >> a;
    while( a < 0 || a > 4)
    {
     cout <<"Year level not recognized! Re Enter Grade level! ";
     cin >> a;
 }

  addfile << a << endl;
   cin.ignore();
  cout << "Enter your Degree and Specialization: ";
  getline(cin,data);
  addfile << data << endl;
  cout <<"Enter your Section: ";
  getline(cin,data);
  addfile << data << endl;
  cout <<"Enter your Academic Year: ";
    getline(cin,data);
  addfile << data << endl;
  cout <<"Enter your Subject: ";
  getline(cin,data);
  addfile << data << endl;

 cout <<"Enter your midterm grade: ";
 cin >> y;
 if (y<60)
 while (y<60 || y > 100)
 {
 cout <<"Invalid Grade! Please re enter Midterm Grade! ";
 cin >> y;
 }
 else if (y>100)
 while (y>100 || y < 60)
 {
 cout <<"Invalid Grade! Please re Midterm Grade! ";
 cin >> y;
 }
addfile << y << endl;
 cout <<"Enter your final grade: ";
 cin >> w;
 if (w<60)
 while (w < 60 || w > 100)
 {
 cout <<"Invalid Grade! Please re enter Final Grade! ";
 cin >> w;
 }
 else if (w>100)
 while (w > 100 || w < 60)
 {
 cout <<" Invalid Grade! Please re enter Final Grade! ";
 cin >> w;
 }

addfile << w << endl;
 m =(y + w) / 2;
 cout <<"Here is your total grade: " << m;
 if (m<60)
 {
 cout <<" No Grade! Please re enter again! \n";
 }
 else if (m>100)
 {
 cout <<" No Grade! Please re enter again! \n";
 }
 addfile << m << endl;
 }
 else if (c==2)
 {
 cout << "Please input the ID Number you wish to edit ";
 cin >> d;
 d+=".txt";
 ifstream myfile;
            myfile.open(d.c_str());
            getline(myfile,data);
            cout <<  "Enter your new information: ";
            cout <<"Full name: " << data << endl;
            cout << "College Year: " << data << endl;
             getline(myfile,data);
 cout << "Degree & Specialization: " << data << endl;
 getline(myfile,data);
            cout << "Section: " << data << endl;
             getline(myfile,data);
            cout << "School Year: " << data << endl;
             getline(myfile,data);
            cout << "Subject: " << data << endl;
             getline(myfile,data);
            cout << "Midterm Grade: " << data << endl;
             getline(myfile,data);
            cout << "Final Grade: " << data << endl;
             getline(myfile,data);
            cout << "Total Grade: " << data << endl;
             getline(myfile,data);
            cout << data << endl;
 }
 else if (c==3)
 {
 cout << "Please input the ID Number you wish to read ";
 cin >> d;
 d+=".txt";
 ifstream myfile;
            myfile.open(d.c_str());
            getline(m