determine_type_of_triangle/MainWindow.axaml.cs

using Avalonia.Controls;
using Avalonia.Interactivity;
using System;

namespace _01_02_MDK
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        enum Triangles
        {
            Isosceles, //Ðàâíîáåäðåííûé
            Equilateral, //Ðàâíîñòîðîííèé
            Versatile, //Ðàçíîñòîðîííèé
            NotExist //Íå ñóùåñòâóåò
        }

        private void pressedButton_Click(object sender, RoutedEventArgs e)
        {
            try {
                var a = Convert.ToInt32(firstSide.Text);
                var b = Convert.ToInt32(secondSide.Text);
                var c = Convert.ToInt32(thirdSide.Text);
                var triangleType = DetermineTypeOfTriangle(a, b, c);
                typeOfTriangle.Text = FromEnumToString(triangleType);
            }

            catch (FormatException)
            {
                typeOfTriangle.Text = "Ââåä¸ííûå çíà÷åíèÿ íåêîððåêòíû. Ïîïðîáóéòå åù¸ ðàç!";
            }

            catch (Exception ex) {
                typeOfTriangle.Text= ex.Message;
            }
        }

        static string FromEnumToString(Triangles triangle)
        {
            return new[] { "Ðàâíîáåäðåííûé", "Ðàâíîñòîðîííèé", "Ðàçíîñòîðîííèé", "Íå ñóùåñòâóåò" }[(int)triangle];
        }

        static Triangles DetermineTypeOfTriangle(int a, int b, int c)
        {
            if (a + b > c && a + c > b && b + c > a)
            {
                if (a == b || b == c || c == a) 
                {
                    if (a == b && b == c)
                        return Triangles.Equilateral;
                    return Triangles.Isosceles;
                }
                return Triangles.Versatile;
            }
            return Triangles.NotExist;
        }
    }
}