Thread: Problem with reading writing in file(no, not that simple)

Hello guys,I just beginner(maybe a bit more than that) at C++ with its basic knowledge.

From what what i know, i tried to make something like facebook, the program isnt complete yet but it isnt working as it is supposed to.
Lets say i open the program and create two accounts, account no.1 and account no.2, then if i login from account 1 and logout, i am not able to login from account 2, and if i login from account 2 and logout, i am not able to login from account 1.

I've been listening to OneD and staring at the screen like a fool for about an hour now looking for that one mistake i am making

So either am making such big mistake that am not able to completely see it or such a small one that am missing it, hope you guys could help.

(Any suggestions about the code are always welcome)

Code:

#include<iostream.h>#include<stdlib.h>
#include<stdio.h>
#include<fstream.h>
#include<string.h>
#include<conio.h>
struct date
{
 int date;
 int monthno;
 int year;
 char month[15];
};
class Account
{
 char password[30];
 char sec_ans[30];


 public:
  char status[150];
  char email[40];
  char name [30];
  char sec_ques[60];
  date b_day;
  void getdata();    //To be used when creating new account
  void open();
  int comp(char id[],char pass[]);
  void change();     // To change account info
  void Upd_stat();
  void getbdate();
  void change_pass();
  void change_mail();
}acc,temp;
void Account :: Upd_stat()
{
 clrscr();
 cout<<"Enter status : ";
 gets(status);
 cout<<"\nStatus updated successfully!";
}
void Account :: change_mail()
{
 clrscr();
 int exist=0;
 char id[40];
 cout<<"Enter new email address : ";
 gets(id);
 ifstream fin("facebuk.dat",ios::in);
 fin.seekg(0);
 while(!fin.eof())
 {
  fin.read((char*)&temp,sizeof(temp));
  if(strcmp(id,temp.email)==0)
  {
    exist=1;
    if(strcmp(id,email)==0)
     cout<<"That is your currecnt email address!";
    else
     cout<<"Account with the email address already exists";
  }
 }
 if(!exist)
 {
  strcpy(email,id);
  cout<<"\nE-mail address changed Successfully!";
 }
 fin.close();
}
void Account :: change_pass()
{
 char pass[30],conf[30];
 clrscr();
 cout<<"Enter your current password : ";
 gets(pass);
 if(strcmp(pass,password))
 {
  cout<<"Wrong password!";
  return;
 }
 do
 {
  cout<<"Enter new password : ";
  gets(pass);
  cout<<"Confirm new password : ";
  gets(conf);
  if(strcmp(pass,conf))
    cout<<"Passwords do not match! Try agian!\n";
 }while(strcmp(pass,conf));
 strcpy(password,pass);
 cout<<"\nPassword canged successfully!";
}
void Account :: getbdate()
{
 int wrong;
 cout<<"Enter Date of Birth :\n";
 do
 {
  wrong=0;
  cout<<"Enter Date(1-31) : ";
  cin>>b_day.date;
  if(b_day.date<1 || b_day.date>31)
  {
    cout<<"Invalid Date!\n";
    wrong=1;
  }
 }while(wrong);
 do
 {
  wrong=0;
  cout<<"Enter month(1-12) : ";
  cin>>b_day.monthno;
  switch(b_day.monthno)
  {
    case 1 : strcpy(b_day.month,"January");
                break;
    case 2 : strcpy(b_day.month,"February");
                break;
    case 3 : strcpy(b_day.month,"March");
                break;
    case 4 : strcpy(b_day.month,"April");
                break;
    case 5 : strcpy(b_day.month,"May");
                break;
    case 6 : strcpy(b_day.month,"June");
                break;
    case 7 : strcpy(b_day.month,"July");
                break;
    case 8 : strcpy(b_day.month,"August");
                break;
    case 9 : strcpy(b_day.month,"September");
                break;
    case 10 : strcpy(b_day.month,"October");
                 break;
    case 11 : strcpy(b_day.month,"November");
                 break;
    case 12 : strcpy(b_day.month,"December");
                 break;
    default : cout<<"Invalid month!\n";
                 wrong=1;
  }
 }while(wrong);
 cout<<"Enter year : ";
 cin>>b_day.year;
}
void Account :: change()
{
 int ch,wrong=0;
 do
 {
  clrscr();
  cout<<"What would you like to change?\n";
  if(wrong)
    cout<<"\t\t\t\tINVALID CHOICE!\n";
  wrong=0;
  cout<<"- Change email address(Press 1)\n- Change Name(Press 2)\n- Change Password(Press 3)\n- Chnage Date of Birth(Press 4)\n";
  cin>>ch;
  switch(ch)
  {
    case 1 : change_mail();
                break;
    case 2 : cout<<"Enter name : ";
                gets(name);
                cout<<"\nName changed successfully!";
                break;
    case 3 : change_pass();
                break;
    case 4 : getbdate();
                cout<<"\nDate of birth changed successfully!";
                break;
    default : wrong=1;
  }
 }while(wrong);
 getch();
}
void Account :: open()
{
 int ch,logout;
 do
 {
  logout=0;
  clrscr();
  cout<<"\t\t\t\tWELCOME ";
  puts(name);
  cout<<"\n\nWhat would you like to do today?\n\n- Update Status(Press 1)\n- Change Account info(Press 2)\n- Logout(Press 3)\n";
  cin>>ch;
  switch(ch)
  {
    case 2 : change();
                break;
    case 3 : logout=1;
                break;
    case 1 : Upd_stat();
                break;
    default : cout<<"\n\n\t\t\tINVALID CHOICE. TRY AGAIN!";
  }
 }while(!logout);
}
int Account :: comp(char id[40],char pass[30])
{
 if(strcmp(id,email)==0 && strcmp(pass,password)==0)
  return 1;
 return 0;
}
void Account :: getdata()
{
 clrscr();
 cout<<"\t\t\t\tCREATE AN ACCOUNT\\n\n";
 cout<<"Enter Name : ";
 gets(name);
 cout<<"Enter Email id : ";
 gets(email);
 getbdate();
 cout<<"Enter password : ";
 gets(password);
 cout<<"Enter a security question(In case you forget your password) : ";
 gets(sec_ques);
 cout<<"Enter the answer to your security question : ";
 gets(sec_ans);
}
void Profile(int pos)
{
 ifstream fi("facebuk.dat",ios::in);
 fi.seekg(pos);
 fi.read((char*)&acc,sizeof(acc));
 fi.close();
 acc.open();
 ofstream fo("facebuk.dat",ios::out);
 fo.seekp(pos);
 fo.write((char*)&acc,sizeof(acc));
 fo.close();
 //ifstream fi("facebuk.dat",ios::in);
}
void login()
{
 char id[40],pass[30],tr;
 int check,again,wrong;
 int pos;
 do
 {
  again=0;
  clrscr();
  cout<<"\t\t\t\t\tLOGIN\n\n";
  cout<<"Enter Email id : ";
  gets(id);
  cout<<"\nEnter password : ";
  gets(pass);
  ifstream fi("facebuk.dat",ios::in);
  fi.seekg(0);
  while(fi)
  {
    pos=fi.tellg();
    fi.read((char*)&acc,sizeof(acc));
    check=acc.comp(id,pass);
    if(check)
     break;
  }
  fi.close();
  if(!check)
  {
    cout<<"Incorrect Email and/or password.Try again?(y/n) ";
    do
    {
     wrong=0;
     cin>>tr;
     switch(tr)
     {
      case 'Y' :
      case 'y' : again=1;
                     break;
      case 'N' :
      case 'n' : again=0;
                     break;
      default : cout<<"Invalid . Try again.";
                    wrong=1;
     }
    }while(wrong);
  }
 }while(again);
 if(check)
  Profile(pos);
}
void create()
{
 acc.getdata();
 ofstream fo("facebuk.dat",ios::out | ios::app);
 fo.write((char*)&acc,sizeof(acc));
 fo.close();
}
void forgot()
{
 cout<<"\nSorry, program under construction!";
 getch();
}
void main()
{
int ch,exit=1,wrong=0;
do
{
 clrscr();
 cout<<"\t\t\t\tWELCOME TO FACEBUK\n\n";
 if(wrong)
 {
  cout<<"\t\t\t    INVALID CHOICE. TRY AGIAN.\n\n";
  wrong=0;
 }
 cout<<"- Login (Press 1)\n- Create a new account (Press 2)\n- Forgot Password? (Press 3)\n- Exit (Press 4)";
 cin>>ch;
 switch(ch)
 {
  case 1 : login();
              break;
  case 2 : create();
              break;
  case 3 : forgot();
              break;
  case 4 : exit=0;
              break;
  default : wrong=1;
 }
}while(exit);
}

I suggest that you work through a somewhat more modern introduction to C++ such as Accelerated C++, which while dated with respect to C++11+, will still give you a very good introduction into how to effectively use C++.

At the moment, the problems with your code are so plentiful that it is difficult to just gloss over them to help you debug your code. For example:

• You use pre-standard headers: <iostream.h> and <fstream.h>
• You are unnecessarily mixing up C++-style I/O with C-style I/O since you also include <stdio.h>
• In addition to mixing with C-style I/O, you use a C I/O function that is inherently vulnerable to buffer overflow: gets
• It is not clear why you chose to use C-style string functions over std::string.
• You incorrectly control loops with fin.eof().
• You don't seem aware of bool.
• Your functions are not const-correct.
• By putting interactive I/O right into your Account class, your member variables become little more than glorified global variables.

Besides these, you should note that <conio.h> and related functions are non-standard, so think carefully if you really need them, and that void main should be int main.

Yes, it really is that old. For up-to-date compilers, you should look at Visual Studio (which is an IDE but comes packed with the compiler), gcc or clang. For IDEs, popular ones include Visual Studio and Code::Blocks. Of course, there are more.

It might not be wrong to read an introductory book either, like Accelerated C++, just to get you started on the right path after that horrible good-for-nothing class. It's a shame schools still teach C++ using that compiler. They should be shamed. They are doing their students a disfavour.