Login and registration system in C++ using file

In this article, we have explained the approach to develop a User Login and Registration System in C++ using file as a database. We have presented the approach with complete C++ code.

The code is portable to C Programming Language so we have used concepts like struct instead of class and so on.

Table of contents:

1. Approach for User Registration
2. C++ code for Registration
3. Approach for User Login
4. C++ code for User Registration and Login using file

Approach for User Registration

We create a structure named user_record to store the username and password and provide critical function like registration.

struct user_record
{
    char username[50];
    char password[50];
    void registration(int);
} obj[5];

The idea of implementing registration function is as follows:

• Open a local file named "registration.txt" as a binary file
• Create the user record with the provided username and password
• Store the user record in the file.
• As the file is in binary, simply opening the file does not leak the username and password.

Following is the registration function:

void user_record::registration(int k)
{
    int i=k;
    cout<<"Enter user name= ";
    cin >> username;
    cout << "Enter password= ";
    cin >> password;

    ofstream filout;
    filout.open("registration.txt", ios::app|ios::binary);
    if(!filout)
    {
        cout<<"\nCannot open file\n";
    }
    else
    {
        cout << "\n";
        filout.write((char *)&obj[i],sizeof(user_record));
        filout.close();
    }
    cout<<"\nYou are registered.";
}

C++ code for Registration

Following is the complete C++ code for user registration using file as a database:

// Part of iq.opengenus.org
#include<iostream>
#include<fstream>
using namespace std;

struct user_record
{
    char username[50];
    char password[50];
    void registration(int);
} obj[5];

void user_record::registration(int k)
{
    int i=k;
    cout<<"Enter user name= ";
    cin >> username;
    cout << "Enter password= ";
    cin >> password;

    ofstream filout;
    filout.open("registration.txt", ios::app|ios::binary);
    if(!filout)
    {
        cout<<"\nCannot open file\n";
    }
    else
    {
        cout << "\n";
        filout.write((char *)&obj[i],sizeof(user_record));
        filout.close();
    }
    cout<<"\nYou are registered.";
}

int main()
{
    int t;
    cout<<"\nEnter Registration Details for User 1 :: \n";
    obj[0].registration(0);
    cout<<"\nEnter Registration Details for User 2 :: \n";
    obj[1].registration(1);
    cout<<"\nEnter Registration Details for User 3 :: \n";
    obj[2].registration(2);

    user_record obj2;

    ifstream filein;
    filein.open("registration.txt",ios::in|ios::binary);
    if(!filein)
    {
        cout<<"\nUnable to open registration database. Please try again later.\n";
    }
    else
    {
        cout<<"\nRegistered Details of All Users :: \n";
        filein.read((char *)&obj2,sizeof(obj2));
        while(filein)
        {
            cout<<"\nUsername :: " << obj2.username << "\nPassword :: " << obj2.password << "\n";
            filein.read((char *)&obj2,sizeof(obj2));
        }
        filein.close();
    }
    return 0;
}

Approach for User Login

The idea of implementing user login function is as follows:

• Open the local file "registration.txt"
• Traverse through the user records in the binary file
• For each record, compare the current username and password provided during login
• If there is a match, login is successful.

Following is the sample implementation of the login function in C++:

void user_record::login(char* current_username, char* current_password)
{
    int success = 0;
    ifstream filein;
    filein.open("registration.txt",ios::in|ios::binary);
    if(!filein)
    {
        cout<<"\nUnable to open registration database. Please try again later.\n";
    }
    else
    {
        filein.read((char *)&obj2,sizeof(obj2));
        while(filein)
        {
            if(current_username == obj2.username && current_password == obj2.password) {
                success = 1;
                break;
            }
            filein.read((char *)&obj2,sizeof(obj2));
        }
        filein.close();
    }
    
    if (success == 1)
        cout << "\nLogin successful.";
    else
        cout << "\nLogin failed.";
}

C++ code for User Registration and Login using file

Following is the complete C++ code for login and registration using file as a database:

// Part of iq.opengenus.org
#include<iostream>
#include<fstream>
using namespace std;

struct user_record
{
    char username[50];
    char password[50];
    void registration(int);
    void login(char*, char*);
} obj[5];

void user_record::registration(int k)
{
    int i=k;
    cout<<"Enter user name= ";
    cin >> username;
    cout << "Enter password= ";
    cin >> password;

    ofstream filout;
    filout.open("registration.txt", ios::app|ios::binary);
    if(!filout)
    {
        cout<<"\nCannot open file\n";
    }
    else
    {
        cout << "\n";
        filout.write((char *)&obj[i],sizeof(user_record));
        filout.close();
    }
    cout<<"\nYou are registered.";
}

void user_record::login(char* current_username, char* current_password)
{
    int success = 0;
    ifstream filein;
    filein.open("registration.txt",ios::in|ios::binary);
    if(!filein)
    {
        cout<<"\nUnable to open registration database. Please try again later.\n";
    }
    else
    {
        filein.read((char *)&obj2,sizeof(obj2));
        while(filein)
        {
            if(current_username == obj2.username && current_password == obj2.password) {
                success = 1;
                break;
            }
            filein.read((char *)&obj2,sizeof(obj2));
        }
        filein.close();
    }

    if (success == 1)
        cout << "\nLogin successful.";
    else
        cout << "\nLogin failed.";
}

int main()
{
    int t;
    cout<<"\nEnter Registration Details for User 1 :: \n";
    obj[0].registration(0);
    cout<<"\nEnter Registration Details for User 2 :: \n";
    obj[1].registration(1);
    cout<<"\nEnter Registration Details for User 3 :: \n";
    obj[2].registration(2);

    user_record obj2;

    ifstream filein;
    filein.open("registration.txt",ios::in|ios::binary);
    if(!filein)
    {
        cout<<"\nUnable to open registration database. Please try again later.\n";
    }
    else
    {
        cout<<"\nRegistered Details of All Users :: \n";
        filein.read((char *)&obj2,sizeof(obj2));
        while(filein)
        {
            cout<<"\nUsername :: " << obj2.username << "\nPassword :: " << obj2.password << "\n";
            filein.read((char *)&obj2,sizeof(obj2));
        }
        filein.close();
    }
    return 0;
}

With this article at OpenGenus, you must have the complete idea of how to implement a C++ program to emulate user registration and login using a file as a database.