Login and Registration System (C++)

📌 Project Overview

This is a simple Login and Registration System developed in C++ as a basic internship-level project.
It allows users to register with a username and password, store credentials in a file, and log in by verifying stored data.

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🎯 Features

• User Registration
• User Login Authentication
• Duplicate username check
• Basic input validation
• File-based data storage
• Simple console-based interface

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🛠️ Technologies Used

• C++
• File Handling (fstream)
• Standard Template Library (string, iostream)

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📂 File Structure

users.txt -> Stores user credentials (username:password) main.cpp -> Source code of the project

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⚙️ How It Works

1. Registration

• User enters username and password
• System checks:
  • Empty input
  • Minimum length (3 characters)
  • Duplicate username
• If valid, data is stored in users.txt in this format:

### 2. Login
- User enters username and password
- System reads users.txt
-If match is found → Login successful
-Otherwise → Error message is shown

### Sample Output

1. Register
2. Login
3. Exit
Enter choice: 1

Enter username: ali
Enter password: 1234
Registration successful!