using System;

​

class Program

{

    // Entry point of the program

    static void Main()

    {

        // Collect customer information

        Console.WriteLine("Enter your first name:");

        string firstName = Console.ReadLine();

        Console.WriteLine("Enter your last name:");

        string lastName = Console.ReadLine();

        Console.WriteLine("Enter your date of birth (YYYY-MM-DD):");

        string dobInput = Console.ReadLine();

​

        // Validate date of birth and ensure the user is at least 18 years old

        DateTime dob;

        if (!DateTime.TryParse(dobInput, out dob))

        {

            Console.WriteLine("Invalid date format. Please enter the date in the correct format.");

            return;

        }

​

        if (CalculateAge(dob) < 18)

        {

            Console.WriteLine("You must be at least 18 years old to register.");

            return;

        }

​

        // Generate User ID

        string userId = GenerateUserId(firstName, lastName, dob.Year);

​

        // Generate a temporary password

        string tempPassword = GeneratePassword();

​

        // Display the results

        Console.WriteLine("\n--- Customer Information ---");

        Console.WriteLine("Full Name: " + firstName + " " + lastName);

        Console.WriteLine("User ID: " + userId);

        Console.WriteLine("Temporary Password: " + tempPassword);

    }

​

    // Function to calculate the age based on the date of birth

    static int CalculateAge(DateTime dob)

    {

        DateTime today = DateTime.Today;

        int age = today.Year - dob.Year;

        if (dob.Date > today.AddYears(-age)) age--; // Adjust for the case when the birthday hasn't occurred yet this year

        return age;

    }

​

    // Function to generate the User ID based on the first name, last name, and birth year

    static string GenerateUserId(string firstName, string lastName, int yearOfBirth)

    {

        // Get the first 3 letters of first and last names, replace with 'x' if less than 3 characters

        string firstPart = firstName.Length >= 3 ? firstName.Substring(0, 3) : firstName + "xxx";

        string lastPart = lastName.Length >= 3 ? lastName.Substring(0, 3) : lastName + "xxx";

        // Construct the User ID by combining first and last parts and the birth year

        string userId = firstPart.ToLower() + lastPart.ToLower() + yearOfBirth;

        return userId;

    }

​

    // Function to generate an 8-character temporary password

    static string GeneratePassword()

    {

        Random rand = new Random();

        char[] password = new char[8];

​

        // Ensure at least one uppercase, one lowercase, and one numeric character

        password[0] = (char)rand.Next(65, 91);  // Uppercase letter (A-Z)

        password[1] = (char)rand.Next(97, 123); // Lowercase letter (a-z)

        password[2] = (char)rand.Next(48, 58);  // Numeric character (0-9)

​

        // Fill in the rest of the password with random characters

        for (int i = 3; i < password.Length; i++)

        {

            int choice = rand.Next(3);

            if (choice == 0)

                password[i] = (char)rand.Next(65, 91);  // Uppercase letter

            else if (choice == 1)

                password[i] = (char)rand.Next(97, 123); // Lowercase letter

            else

                password[i] = (char)rand.Next(48, 58);  // Numeric character

        }

​

        // Shuffle the password to ensure randomness in the order

        Shuffle(password, rand);

​

        // Convert the character array to a string and return

        return new string(password);

    }

​

    // Function to shuffle an array (Fisher-Yates shuffle algorithm)

    static void Shuffle(char[] array, Random rand)

    {

        for (int i = array.Length - 1; i > 0; i--)

        {

            int j = rand.Next(i + 1);

            char temp = array[i];

            array[i] = array[j];

            array[j] = temp;

        }

    }

}

​