NewAuthAndCaptcha/AuthAndCaptcha/ViewModels/CalculatorViewModel.cs

using System;
using System.Collections.Generic;
using ReactiveUI;
using Tmds.DBus.Protocol;

namespace AuthAndCaptcha.ViewModels
{
	public class CalculatorViewModel : ReactiveObject
	{
		public static List<string> calcOptions => new List<string>() {"Ñëîæåíèå", "Âû÷èòàíèå", "Óìíîæåíèå", "Äåëåíèå"};

        string selectedOption = calcOptions[0];
        public string SelectedOption { get => selectedOption; set { this.RaiseAndSetIfChanged(ref selectedOption, value); ChangeSign(); } }
        char sign = '+';
        public char Sign { get => sign; set => this.RaiseAndSetIfChanged(ref sign, value); }
        int n, m, result;
        public int N { get => n; set => n = value; }
        public int M { get => m; set => m = value; }
        public int Result { get => result; set => this.RaiseAndSetIfChanged(ref result, value); }

        public void ChangeSign() 
		{
			if (SelectedOption == "Ñëîæåíèå") Sign = '+';
			else if (SelectedOption == "Âû÷èòàíèå") Sign = '-';
            else if (SelectedOption == "Óìíîæåíèå") Sign = '*';
            else if (SelectedOption == "Äåëåíèå") Sign = '/';
        }
        
        public void Calculation()
        {
            if (SelectedOption == "Ñëîæåíèå") Result = N + M;
            else if (SelectedOption == "Âû÷èòàíèå") Result = N - M;
            else if (SelectedOption == "Óìíîæåíèå") Result = N * M;
            else if (SelectedOption == "Äåëåíèå") Result = N / M;
        }

	}
}