How to Create a Basic Login System Using Python

Creating a basic login system in Python is straightforward and can be achieved through various methods. This tutorial will walk you through the process of building a simple login system using a dictionary to store user credentials and functions to handle user input.

Step-by-Step Guide to Create a Simple Login System

Step 1: Set Up User Data

The first step is to set up user data. You can store user credentials in a dictionary for demonstration purposes. In a real application, you would typically use a database to store user data securely.

users { }

Step 2: Create a Login Function

The next step is to create a function that prompts the user for a username and password, and checks if the entered credentials match the stored credentials.

def login(): username input('Enter your username: ') password input('Enter your password: ') if username in users and users[username] password: print('Login successful!') else: print('Login failed. Please try again.')

Step 3: Create a Registration Function (Optional)

If you want to allow new users to register, you can do that by creating a registration function as shown below.

def register(): username input('Enter a new username: ') password input('Enter a new password: ') if username in users: print('Username already exists. Please try a different one.') else: users[username] password print('Registration successful!')

Step 4: Main Loop

To allow users to log in or register as needed, create a loop that continually prompts the user for a choice until they decide to exit.

def main(): while True: choice input('Enter "login" to log in, "register" to register, or "exit" to quit: ') if choice 'login': login() elif choice 'register': register() elif choice 'exit': print('Goodbye!') break else: print('Invalid choice. Please try again.')

Complete Code Example

Here is the complete code for the login system:

users { } def login(): username input('Enter your username: ') password input('Enter your password: ') if username in users and users[username] password: print('Login successful!') else: print('Login failed. Please try again.') def register(): username input('Enter a new username: ') password input('Enter a new password: ') if username in users: print('Username already exists. Please try a different one.') else: users[username] password print('Registration successful!') def main(): while True: choice input('Enter "login" to log in, "register" to register, or "exit" to quit: ') if choice 'login': login() elif choice 'register': register() elif choice 'exit': print('Goodbye!') break else: print('Invalid choice. Please try again.') if __name__ '__main__': main()

Note: Security Considerations

While this example is suitable for learning and testing, it is not secure for real-world applications. Here are some security recommendations:

Hash passwords using libraries like bcrypt or hashlib. Store user data in a database. Implement measures against brute-force attacks, such as account lockout after several failed attempts.

User Experience

Consider adding features such as password recovery, account lockout after several failed attempts, and input validation for a better user experience.

This example should help you get started with building a login system in Python! If you have any questions or need further details, feel free to ask.