Program.cs

string userInput = "";
List<string> operationHistory = new List<string>();
do
{
    Console.WriteLine("=== Welcome to Math Game ===");
    Console.WriteLine("Select an operation:");
    Console.WriteLine("1. Addition (a + b)");
    Console.WriteLine("2. Subtraction (a - b)");
    Console.WriteLine("3. Multiplication (a * b)");
    Console.WriteLine("4. Division (a / b, result must be integer, dividend ≤ 100)");
    Console.WriteLine("5. View operation history");
    Console.WriteLine("Type 'Exit' to quit the game.");
    Console.Write("Your choice: ");
    userInput = Console.ReadLine();

    string logUserHistory;

    switch (userInput)
    {
        case "1":
            Console.Write("Enter two numbers separated by a comma (e.g., 5,3): ");
            var additionInput = Console.ReadLine();
            string[] additionValues = additionInput.Split(",");
            var additionOutput = int.Parse(additionValues[0]) + int.Parse(additionValues[1]);
            Console.WriteLine($"Addition Result: {additionValues[0]} + {additionValues[1]} = {additionOutput}");
            logUserHistory = $"{additionValues[0]} + {additionValues[1]} = {additionOutput}";
            operationHistory.Add(logUserHistory);
            break;
        case "2":
            Console.Write("Enter two numbers separated by a comma (e.g., 5,3): ");
            var subtractionInput = Console.ReadLine();
            string[] subtractionValues = subtractionInput.Split(",");
            int subtractionOutput = int.Parse(subtractionValues[0]) - int.Parse(subtractionValues[1]);
            Console.WriteLine($"Subtraction Result: {subtractionValues[0]} - {subtractionValues[1]} = {subtractionOutput}");
            logUserHistory = $"{subtractionValues[0]} - {subtractionValues[1]} = {subtractionOutput}";
            operationHistory.Add(logUserHistory);
            break;
        case "3":
            Console.Write("Enter two numbers separated by a comma (e.g., 5,3): ");
            var multiplicationInput = Console.ReadLine();
            string[] multiplicationValues = multiplicationInput.Split(",");
            var multiplicationOutput = int.Parse(multiplicationValues[0]) * int.Parse(multiplicationValues[1]);
            Console.WriteLine($"Multiplication Result: {multiplicationValues[0]} * {multiplicationValues[1]} = {multiplicationOutput}");
            logUserHistory = $"{multiplicationValues[0]} * {multiplicationValues[1]} = {multiplicationOutput}";
            operationHistory.Add(logUserHistory);
            break;
        case "4":
            Console.WriteLine("Division: The dividend must be ≤ 100 and result must be an integer.");
            Console.Write("Enter the divisor: ");
            int divisorInput = int.Parse(Console.ReadLine());
            Console.Write("Enter the dividend: ");
            int dividendInput = int.Parse(Console.ReadLine());

            if (divisorInput == 0)
            {
                Console.WriteLine("Error: Division by zero is not allowed.");
                break;
            }
            if (dividendInput > 100)
            {
                Console.WriteLine("Error: The dividend must be 100 or less.");
                break;
            }
            if (dividendInput % divisorInput != 0)
            {
                Console.WriteLine("Error: The result is not an integer. Please try again.");
                break;
            }

            var divisionOutput = dividendInput / divisorInput;
            Console.WriteLine($"Division Result: {dividendInput} / {divisorInput} = {divisionOutput}");
            logUserHistory = $"{dividendInput} / {divisorInput} = {divisionOutput}";
            operationHistory.Add(logUserHistory);

            break;

        case "5":
            Console.WriteLine("=== Operation History ===");
            if (operationHistory.Count == 0)
            {
                Console.WriteLine("No operations performed yet.");
            }
            else
            {
                foreach (string history in operationHistory)
                {
                    Console.WriteLine(history);
                }
            }
            break;
    }

} while (userInput != "Exit");