C# - Xamarin - 型と参照 - 10時です。データがどこにあるかわかりますか？(オブジェクト、配列、whileループ)

Head First C#
原著

開発環境

• OS: Windows 10 Pro
• IDE(統合開発環境): Visual Studio Community 2017

Head First C# ―頭とからだで覚えるC#の基本 (Andrew Stellman (著)、Jennifer Greene (著)、佐藤 嘉一 (監修, 監修)、木下 哲也 (翻訳)、オライリージャパン)の4章(型と参照 - 10時です。データがどこにあるかわかりますか？)、プールパズル(p. 159)を取り組んでみる。

コード

MainPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:App1"
             x:Class="App1.MainPage">

    <StackLayout>
        <!-- Place new controls here -->
        <!--
     <Label Text="Welcome to Xamarin.Forms!" 
           HorizontalOptions="Center"
           VerticalOptions="CenterAndExpand" />
        -->
    </StackLayout>

</ContentPage>

MainPage.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace App1
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();

            Triangle triangle = new Triangle();
            triangle.Run();
        }
    }

    public class Triangle: ContentPage
    {
        double area;
        int height;
        int length;
        
        public void Run()
        {
            string results = "";
            int x = 0;
            int y = x;
            Triangle[] triangles = new Triangle[4];
            while (x < 4)
            {
                triangles[x] = new Triangle();
                triangles[x].height = (x + 1) * 2;
                triangles[x].length = x + 4;
                triangles[x].setArea();
                results += "三角形 " + x + ", 面積";
                results += " = " + triangles[x].area + "\n";
                x += 1;
            }
            x = 27;
            Triangle t5 = triangles[2];
            triangles[2].area = 343;
            results += "y = " + y;

            DisplayAlert("", results + ", t5 面積 = " + t5.area, "OK");
        }

        void setArea()
        {
            area = height * length / 2;
        }
    }
}

App.xaml

<?xml version="1.0" encoding="utf-8" ?>
<Application xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="App1.App">
    <Application.Resources>
        
    </Application.Resources>
</Application>

App.xaml.cs

using System;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

[assembly: XamlCompilation (XamlCompilationOptions.Compile)]
namespace App1
{
 public partial class App : Application
 {
  public App ()
  {
   InitializeComponent();

            // MainPage = new MainPage();
            MainPage = new NavigationPage(
                new MainPage() { Title = "" });
  }

  protected override void OnStart ()
  {
   // Handle when your app starts
  }

  protected override void OnSleep ()
  {
   // Handle when your app sleeps
  }

  protected override void OnResume ()
  {
   // Handle when your app resumes
  }
 }
}