如何重构我的 C# 代码，以免重复自己？

Question

I have built a multiplication project that asks the user a difficulty level and the number of questions they want to answer and then the user will answer the random multiplication questions!

But I am trying to refactor the code so I don't repeat myself too many times.

Can anyone please help me make the code less repeatable?

Here is the code:

using System;

namespace mathstester
{
    class Program
    {
        public static void Main(string[] args)
        {
            string userDifficulty = "";
            do
            {
                Console.WriteLine("What difficulty level would you like to do! Please type E for Easy, N for Normal and H for hard");
                userDifficulty = Console.ReadLine().ToUpper();
            }while (userDifficulty != "E" && userDifficulty != "N" && userDifficulty != "H");

            int numberOfQuestions = 0;
            int numberOfQuestionsLeft = 0;
            do
            {
                Console.Write("How many questions would you like to answer?Please type a number divisible by 10");
                int.TryParse(Console.ReadLine(), out numberOfQuestions);
                numberOfQuestionsLeft = numberOfQuestions;
            } while (numberOfQuestions % 10 != 0);

            Random random = new Random();
            int easyNumber1 = random.Next(10);
            int easyNumber2 = random.Next(10);
            int normalNumber1 = random.Next(100);
            int normalNumber2 = random.Next(100);
            int hardNumber1 = random.Next(10, 1000);
            int hardNumber2 = random.Next(10, 1000);
            int score = 0;

            while (numberOfQuestionsLeft > 0)
            {
                if (userDifficulty == "E")
                {
                    Console.Write($"What is {easyNumber1} * {easyNumber2} =");
                    int correctAnswer = easyNumber1 * easyNumber2;
                    int userAnswer = Convert.ToInt32(Console.ReadLine());
                    if (correctAnswer == userAnswer)
                    {
                        Console.WriteLine("Well Done!");
                        score++;
                    }
                    else
                    {
                        Console.WriteLine("Your answer is incorrect!");
                    }
                    numberOfQuestionsLeft--;
                    easyNumber1 = random.Next(10);
                    easyNumber2 = random.Next(10);
                }
                else if (userDifficulty == "N")
                {
                    Console.Write($"What is {normalNumber1} * {normalNumber2} =");
                    int correctAnswer = normalNumber1 * normalNumber2;
                    int userAnswer = Convert.ToInt32(Console.ReadLine());
                    if (correctAnswer == userAnswer)
                    {
                        Console.WriteLine("Well Done!");
                        score++;
                    }
                    else
                    {
                        Console.WriteLine("Your answer is incorrect!");
                    }
                    numberOfQuestionsLeft--;
                    normalNumber1 = random.Next(100);
                    normalNumber2 = random.Next(100);
                }
                else if (userDifficulty == "H")
                {
                    Console.Write($"What is {hardNumber1} * {hardNumber2} =");
                    int correctAnswer = hardNumber1 * hardNumber2;
                    int userAnswer = Convert.ToInt32(Console.ReadLine());
                    if (correctAnswer == userAnswer)
                    {
                        Console.WriteLine("Well Done!");
                        score++;
                    }
                    else
                    {
                        Console.WriteLine("Your answer is incorrect!");
                    }
                    numberOfQuestionsLeft--;
                    hardNumber1 = random.Next(10, 1000);
                    hardNumber2 = random.Next(10, 1000);
                }
            }
            Console.WriteLine($"You got a score of {score} out of {numberOfQuestions}");
        }
    }
}

Thank You in advance!

Answer 1

Just move the part that defines the numbers away from the rest, and don't use different variables for each difficulty. Also, it is enough to initialize their values before the question, no need to do it before and afterwards.

using System;

namespace mathstester
{
    class Program
    {
        public static void Main(string[] args)
        {
            string userDifficulty = "";
            do
            {
                Console.WriteLine("What difficulty level would you like to do! Please type E for Easy, N for Normal and H for hard");
                userDifficulty = Console.ReadLine().ToUpper();
            } while (userDifficulty != "E" && userDifficulty != "N" && userDifficulty != "H");

            int numberOfQuestions = 0;
            int numberOfQuestionsLeft = 0;
            do
            {
                Console.Write("How many questions would you like to answer? Please type a number divisible by 10");
                int.TryParse(Console.ReadLine(), out numberOfQuestions);
                numberOfQuestionsLeft = numberOfQuestions;
            } while (numberOfQuestions % 10 != 0);

            Random random = new Random();
            int score = 0;

            while (numberOfQuestionsLeft > 0)
            {
                // Here we define two variables for the numbers
                // and set their values based on the difficulty.
                // Everything else is the same in all cases!
                int number1 = 0;
                int number2 = 0;

                if (userDifficulty == "E") {
                  number1 = random.Next(10);
                  number2 = random.Next(10);
                } else if (userDifficulty == "N") {
                  number1 = random.Next(100);
                  number2 = random.Next(100);
                } else if (userDifficulty == "H") {
                  number1 = random.Next(10, 1000);
                  number2 = random.Next(10, 1000);
                }

                // This code is the same for all difficulty levels!
                Console.Write($"What is {number1} * {number2} =");
                int correctAnswer = number1 * number2;
                int userAnswer = Convert.ToInt32(Console.ReadLine());
                if (correctAnswer == userAnswer)
                {
                    Console.WriteLine("Well Done!");
                    score++;
                }
                else
                {
                    Console.WriteLine("Your answer is incorrect!");
                }
                numberOfQuestionsLeft--;
           }
            Console.WriteLine($"You got a score of {score} out of {numberOfQuestions}");
        }
    }
}