Program.cs

namespace ClassMethod2
{
    using System;
    using System.Drawing;
    using static System.Runtime.InteropServices.JavaScript.JSType;

    internal class Program
    {
        static void Main(string[] args)
        {
            bool running = true;

            while (running)
            {
                Console.WriteLine("If you want to exit the program enter 'exit' or 'quit'.");
                Console.WriteLine("Press any key to enter the program...");
                Console.ReadKey();
                string command = Console.ReadLine();
                

                // Check if the user wants to exit
                if (command.Equals("exit", StringComparison.OrdinalIgnoreCase) ||
                    command.Equals("quit", StringComparison.OrdinalIgnoreCase))
                {
                    running = false;
                    break; // Exit the loop
                }

                //CONSOLE
                // 1. Ask for name and favorite color
                Console.WriteLine("What is your name:");
                string name = Console.ReadLine();

                Console.WriteLine("\nWhat is your favorite colour:");
                string favColour = Console.ReadLine();

                Console.Clear();

                // 2. Convert string to ConsoleColor
                if (Enum.TryParse(favColour, true, out ConsoleColor color))
                {
                    Console.ForegroundColor = color;
                    Console.WriteLine($"Hello {name}!");
                }
                else
                {
                    Console.WriteLine("Invalid color! Using default.");
                }

                // 3. Ask for two numbers and show sum
                Console.WriteLine("\nEnter one digit:");
                double num1 = int.Parse(Console.ReadLine());
                Console.WriteLine("Enter another digit:");
                double num2 = int.Parse(Console.ReadLine());

                Console.WriteLine($"You have entered {num1} and {num2}. The sum of your digits is {num1 + num2}");


                //MATH
                // 1. square root
                Console.WriteLine("\nEnter one digit:");
                double num3 = int.Parse(Console.ReadLine());
                Console.WriteLine($"You have entered {num3}. The square root of your digits is {Math.Sqrt(num3)}");

                // 2. Ask for two numbers and show smallest
                Console.WriteLine("\nEnter one digit:");
                double num4 = int.Parse(Console.ReadLine());
                Console.WriteLine("Enter another digit:");
                double num5 = int.Parse(Console.ReadLine());
                Console.WriteLine($"Your smallest number is {Math.Min(num4, num5)}");

                // 3. Radius of a circle
                Console.WriteLine("\nEnter the radius of the circle:");
                double radius = double.Parse(Console.ReadLine());
                Console.WriteLine($"The area of the circle with radius {radius} is {Math.PI * Math.Pow(radius, 2)}");


                //RANDOM
                // 1. Generate a random number
                Random rand = new Random();
                int dice = rand.Next(1, 7); // 1 to 6
                Console.WriteLine($"\nThe number on the dice is {dice}");

                // 2. Simple lottery simulation
                int secretNumber = rand.Next(1, 11); // 1 to 10
                Console.WriteLine("Guess a number between 1 and 10:");
                int guess = int.Parse(Console.ReadLine());

                if (guess == secretNumber)
                    Console.WriteLine("You guessed it!");
                else
                    Console.WriteLine($"Wrong! The number was {secretNumber}");

                // 3. Generate three random colors (using RGB values)
                for (int i = 1; i <= 3; i++)
                {
                    int r = rand.Next(0, 256); // Red component (0-255)
                    int g = rand.Next(0, 256); // Green component (0-255)
                    int b = rand.Next(0, 256); // Blue component (0-255)

                    Color randomColor = Color.FromArgb(r, g, b);
                    Console.WriteLine($"Color {i}: R={r}, G={g}, B={b}");
                }

                
                //DateTime
                //1. Birthdate
                Console.WriteLine("Enter your birthdate (yyyy-MM-dd):");
                string input = Console.ReadLine();

                // Parse the input into a DateTime object
                if (DateTime.TryParse(input, out DateTime birthdate))
                {
                    DateTime today = DateTime.Today;

                    // Calculate age
                    int age = today.Year - birthdate.Year;

                    // If birthday hasn't occurred yet this year, subtract 1
                    if (birthdate.Date > today.AddYears(-age))
                    {
                        age--;
                    }

                    Console.WriteLine($"You are {age} years old.");
                }
                else
                {
                    Console.WriteLine("Invalid date format. Please use yyyy-MM-dd.");
                }


                //2. Day of the week 
                string filePath = "event.txt"; // File to store the even

                // Check if an event was saved before
                if (File.Exists(filePath))
                {
                    string savedEvent = File.ReadAllText(filePath);
                    Console.WriteLine($"Reminder: Your last event was - {savedEvent}");
                }

                // Get today's day of the week
                DateTime today = DateTime.Today;
                DayOfWeek dayOfWeek = today.DayOfWeek;

                Console.WriteLine($"Today is {dayOfWeek}, enter your event for today:");
                string e = Console.ReadLine();

                // Save the event to file
                File.WriteAllText(filePath, e);

                Console.WriteLine("Your event has been saved. Run the program again to be reminded!");


                // 3. Difference in days between today and the next holiday
                // Get today's date
                Console.WriteLine("Enter the date of your next holiday (yyyy-mm-dd):");
                string yourDay = Console.ReadLine();

                // Try to parse the yourDay
                if (DateTime.TryParse(yourDay, out DateTime holiday))
                {
                    if (holiday < today)
                    {
                        Console.WriteLine("That holiday has already passed!");
                    }
                    else
                    {
                        // Calculate difference
                        TimeSpan difference = holiday - today;
                        Console.WriteLine($"Your holiday is in {difference.Days} day(s).");
                    }
                }
                else
                {
                    Console.WriteLine("Invalid date format. Please enter in yyyy-mm-dd format.");
                }


                // STRING
                // 1. reverse order
                Console.WriteLine("Enter any sentence: ");
                string sentence = Console.ReadLine();

                // Convert string to char array and reverse
                char[] chars = sentence.ToCharArray();
                Array.Reverse(chars);

                // Create reversed string
                string reversed = new string(chars);

                Console.WriteLine("Reversed sentence:");
                Console.WriteLine(reversed);

                
                // 2. palindrome
                // Normalize input (remove spaces, make lowercase)
                string cleaned = sentence.Replace(" ", "").ToLower();

                // Reverse the string
                char[] chars2 = cleaned.ToCharArray();
                Array.Reverse(chars);
                string reversed2 = new string(chars2);

                // Compare original and reversed
                if (cleaned == reversed2)
                {
                    Console.WriteLine("It is a palindrome!");
                }
                else
                {
                    Console.WriteLine("It is not a palindrome.");
                }

                // 3. how many times a specific word appears
                Console.WriteLine("Enter a paragraph: ");
                string paragraph = Console.ReadLine();

                Console.WriteLine("Enter the word to count:");
                string wordToCount = Console.ReadLine();

                // Normalize case for case-insensitive comparison
                string[] words = paragraph.Split(new char[] { ' ', '.', ',', '!', '?', ';', ':', '\n', '\r' }, StringSplitOptions.RemoveEmptyEntries);
                int count = 0;

                foreach (string word in words)
                {
                    if (word.Equals(wordToCount, StringComparison.OrdinalIgnoreCase))
                    {
                        count++;
                    }
                }

                Console.WriteLine($"The word \"{wordToCount}\" appears {count} time(s) in the paragraph.");


                // ARRAY
                // 1. reverse order in array
                int[] numbers = new int[5];

                Console.WriteLine("Enter any 5 numbers:");
                for (int i = 0; i < numbers.Length; i++)
                {
                    Console.Write($"Number {i + 1}: ");
                    numbers[i] = int.Parse(Console.ReadLine());
                }

                // Print numbers in reverse order
                Console.WriteLine("\nNumbers in reverse order:");
                for (int i = numbers.Length - 1; i >= 0; i--)
                {
                    Console.WriteLine(numbers[i]);
                }


                // 2. convert string into a character array and count how many vowels are in the string
                Console.Write("Enter a word: ");
                string str = Console.ReadLine();

                char[] characters = str.ToCharArray();

                int vowelCount = 0;

                foreach (char c in characters)
                {
                    char lowerChar = Char.ToLower(c); 
                    if (lowerChar == 'a' || lowerChar == 'e' || lowerChar == 'i' || lowerChar == 'o' || lowerChar == 'u')
                    {
                        vowelCount++;
                    }
                }

                Console.WriteLine($"The string contains {vowelCount} vowels.");


                // 3. Create a program where the user can continually add names
                List<string> names = new List<string>();
                string input2;

                Console.WriteLine("Enter names. Type 'stop' when you want to finish.");

                // Loop until the user types "stop"
                while (true)
                {
                    Console.Write("Enter a name: ");
                    input2 = Console.ReadLine();

                    // Check if the user wants to stop
                    if (input2.ToLower() == "stop")
                        break;

                    // Add the name to the list
                    names.Add(input2);
                }

                // Display all names entered
                Console.WriteLine("\nNames entered:");
                foreach (string name2 in names)
                {
                    Console.WriteLine(name2);
                }

                // Display the total count
                Console.WriteLine($"\nTotal number of names entered: {names.Count}");



            }
        }
    }
}