Rock, paper, scissors, c#

Question

I am a beginner programmer trying to go past the simple tutorials like Codecademy. I decided to make a rock paper scissors game to get some practice in making projects. Any feedback is welcome!

using System;
using System.Reflection.Metadata.Ecma335;
using System.Runtime.CompilerServices;

namespace ConsoleApp1
{
    class Program
    {
        static public int game()
        {
            int winner = 0;
            int input;
            Random random = new Random();
            //show options
            Console.WriteLine("1.Rock");
            Console.WriteLine("2.Paper");
            Console.WriteLine("3.Scissors");
            //get user input
            try
            {
                input = Convert.ToInt32(Console.ReadLine());
            }
            catch
            {
                input = 4;
            }
            //pick random input for opponent
            int opponent = random.Next(3);
            Console.Clear();
            //logic and stuff
            if(input == 1)
            {
                if(opponent == 0)
                {
                    Console.WriteLine("Tie! The opponent picked rock.");
                    winner = 0;
                }
                else if(opponent == 1)
                {
                    Console.WriteLine("you lost! The opponent picked paper.");
                    winner = 1;
                }
                else if(opponent == 2)
                {
                    Console.WriteLine("you won! The opponent picked scissors.");
                    winner = 2;
                }

            }
            else if(input == 2)
            {
                if (opponent == 0)
                {
                    Console.WriteLine("you won! The opponent picked scissors.");
                    winner = 2;
                }
                else if (opponent == 1)
                {
                    Console.WriteLine("Tie! The opponent picked paper.");
                    winner = 0;
                }
                else if (opponent == 2)
                {
                    Console.WriteLine("you lost! The opponent picked scissors.");
                    winner = 1;
                }

            }
            else if(input == 3)
            {
                if (opponent == 0)
                {
                    Console.WriteLine("you lost! The opponent picked rock.");
                    winner = 1;
                }
                else if(opponent == 1)
                {
                    Console.WriteLine("you won! The opponent picked scissors.");
                    winner = 2;
                }
                else if(opponent == 2)
                {
                    Console.WriteLine("Tie! The opponent picked scissors.");
                    winner = 0;
                }

            }
            else
            {
                Console.WriteLine("Pick a Number between 1 and 3!");
                winner = 0;
            }
            //return score
            return winner;
        }
        static void Main(string[] args)
        {
            int playerScore = 0;
            int opponentScore = 0;
            bool keepPlaying = true;
            char i = 'y';
            Console.WriteLine("Welcome to Rock paper scissors!");
            
            while (keepPlaying)
            {
                int gameResult = game();
                
                if (gameResult == 1)
                {
                    opponentScore++;
                }
                else if (gameResult == 2)
                {
                    playerScore++;
                }
                else if(gameResult != 0)
                {
                    Console.WriteLine("Something went wrong!");
                }
                string s = String.Format("Your score:{0} Opponents score:{1}", playerScore, opponentScore);
                Console.WriteLine(s);
                Console.WriteLine("Do you want to keep playing? y/n");
                try
                {
                    i = Convert.ToChar(Console.ReadLine());
                }
                catch
                {
                    i = 'n';
                }
                if (i != 'y')
                {
                    keepPlaying = false;
                }
                
            }
        }
    }
}
```

Answer 1

You mix data and logic, this is bad seperarion and makes the code hard to maintain and refactor.

I would move the rules to a data structure and query it for who is winner. Here is an example i did for another stackexhange question.

class Program
{
    private enum Type
    {
        Rock = 0, 
        Paper = 1,
        Scissor = 2
    }

    private interface IPLayerInput
    {
        Type GetInput();
    }

    private class KeyboardPlayerInput : IPLayerInput
    {
        public Type GetInput()
        {
            return (Type)Enum.Parse(typeof(Type), Console.ReadLine() ?? string.Empty);
        }
    }

    private class AiPLayerInput : IPLayerInput
    {
        private readonly Type[] _values;
        private readonly Random _rand;

        public AiPLayerInput()
        {
            _values = Enum.GetValues(typeof(Type)).Cast<Type>().ToArray();
            _rand = new Random();
        }

        public Type GetInput()
        {
            return _values[_rand.Next(0, _values.Length)];
        }
    }

    private class Player
    {
        private readonly IPLayerInput _input;

        public Player(string name, IPLayerInput input)
        {
            _input = input;
            Name = name;
        }

        public int Score { get; set; }
        public string Name { get; }

        public void RequestNewHand()
        {
            CurrentHand = _input.GetInput();
        }

        public Type CurrentHand { get; private set; } 
    }

    static void Main()
    {
        var rules = new Type?[,] { 
            { null, Type.Paper, Type.Rock }, 
            { Type.Paper, null, Type.Scissor }, 
            { Type.Rock, Type.Scissor, null } };


        var players = new List<Player> {new Player("AI", new AiPLayerInput()), new Player("Hooman", new KeyboardPlayerInput())};

        Player winner = null;
        while (winner == null)
        {
            players.ForEach(p => p.RequestNewHand());
            foreach (var player in players)
            {
                var score = players.Count(p => p != player && rules[(int)player.CurrentHand, (int)p.CurrentHand] == player.CurrentHand);
                player.Score += score;
            }

            winner = players.SingleOrDefault(p => p.Score >= 3);
        }

        Console.WriteLine($"Winner is {winner.Name}");

    }
}

Answer 2

Here are a few links https://docs.microsoft.com/en-us/dotnet/api/system.int32.tryparse?view=netcore-3.1 A newer method of parsing an Int32 in C#.

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/switch a way to simplify your if statements.

Also, it isn't the best practice to put a lot of code into the main method. Try adding a public void static run() method and then calling that from the main method.

using System;
using System.Collections.Generic;
using System.Text;

namespace RockPaperScissors
{
    class Program
    {
        public static int playerScore = 0;
        public static int opponentScore = 0;

        static void Main(string[] args)
        {
            run();
        }

        public static void run()
        {
            bool? roundResult = null;
            bool playAgain = false;
            Random rng = new Random();
            int opponentNumber = rng.Next(1, 4);

            while (roundResult == null || playAgain)
            {
                Console.WriteLine("1.Rock\n2.Paper\n3.Scissors");
                Console.Write("Please Input A Number: ");

                Int32.TryParse(Console.ReadLine(), out int input);
                //Console.WriteLine(input);

                roundResult = compare(input, opponentNumber);
                if (roundResult == null)
                {
                    Console.WriteLine("\nRound Was A Tie. Try Again\n");
                    Console.WriteLine();
                }

                Console.WriteLine($"\nPlayer Score: {playerScore}\nOpponent Score: {opponentScore}\n");

                if (roundResult != null)
                {

                    bool validInput = false;
                    while (!validInput)
                    {
                        Console.Write("\nPlay Again? Y/N: ");
                        string playAgainInput = Console.ReadLine().ToLower();
                        switch (playAgainInput)
                        {
                            case "y":
                                playAgain = true;
                                validInput = true;
                                break;
                            case "n":
                                playAgain = false;
                                validInput = true;
                                break;
                            default:
                                Console.WriteLine("Invalid Input");
                                validInput = false;
                                break;
                        }
                    }
                }
            }



        }

        public static string getHandForm(int number)
        {
            string handForm = "";
            switch (number)
            {
                case 1:
                    handForm = "Rock";
                    break;
                case 2:
                    handForm = "Paper";
                    break;
                case 3:
                    handForm = "Scissors";
                    break;
                default:
                    Console.WriteLine("Invalid Number");
                    break;
            }

            return handForm;
        }

        public static bool? compare(int player, int opponent)
        {

            string playerHand = getHandForm(player);
            string opponentHand = getHandForm(opponent);
            //True equals Round Won, False equals Round Loss, Null equals round tie
            bool? roundBool = null;

            if (opponent != player)
            {
                switch (playerHand)
                {
                    case "Rock":
                        switch (opponentHand)
                        {
                            case "Scissors":
                                //Player Wins
                                roundBool = true;
                                break;
                            case "Paper":
                                //Player Loses
                                roundBool = false;
                                break;
                        }
                        break;
                    case "Scissors":
                        switch (opponentHand)
                        {
                            case "Rock":
                                //Player Loses
                                roundBool = false;
                                break;
                            case "Paper":
                                //Player Wins
                                roundBool = true;
                                break;
                        }
                        break;
                    case "Paper":
                        switch (opponentHand)
                        {
                            case "Rock":
                                //Player Wins
                                roundBool = true;
                                break;
                            case "Scissors":
                                //Player Loses
                                roundBool = false;
                                break;
                        }
                        break;
                }
            }

            if (roundBool == true)
            {
                Console.WriteLine($"Player Wins! Opponent Choose: {opponentHand} You Choose: {playerHand}");
                playerScore++;
            }
            else if (roundBool == false)
            {
                Console.WriteLine($"Opponent Wins! Opponent Choose: {opponentHand} You Choose: {playerHand}");
                opponentScore++;
            }

            return roundBool;
        }

    }
}