C#初心者を卒業しよう(第2回の解答例)

プログラム

Program.cs

var service = new DistanceService();
service.Run();

public interface IDistance
{
    void Calculate(double diatance);
    string CreateAnswerMessage();
}

public class DistanceService
{
    public void Run()
    {
        var convertNumber = InputConvertNumber();
        var distanceObject = Create(convertNumber);

        var distance = InputDistance();
        distanceObject.Calculate(distance);

        OutputAnswer(distanceObject);
    }

    protected virtual int InputConvertNumber()
    {
        Console.WriteLine("Please input convert number.");
        Console.WriteLine("1 : Convert meters to yards.");
        Console.WriteLine("2 : Convert yards to meters.");
        Console.WriteLine("3 : Convert meters to feet.");
        Console.WriteLine("4 : Convert feet to meters.");
        if (!int.TryParse(Console.ReadLine(), out var convertNumber))
        {
            throw new FormatException("Invalid input convert number.");
        }
        return convertNumber;
    }

    protected virtual IDistance Create(int convertNumber)
    {
        switch (convertNumber)
        {
            case 1:
                return new ToYards();
            case 2:
                return new ToMeters();
            case 3:
                return new MetersToFeet();
            case 4:
                return new FeetToMeters();
            default:
                throw new ArgumentOutOfRangeException(
                    $"{convertNumber} is out of range.");
        }
    }

    protected virtual double InputDistance()
    {
        Console.WriteLine("Please input distance.");
        if (!double.TryParse(Console.ReadLine(), out var distance))
        {
            throw new FormatException("Invalid input distance.");
        }
        return distance;
    }

    protected virtual void OutputAnswer(IDistance distance)
    {
        var outputMessage = distance.CreateAnswerMessage();
        Console.WriteLine(outputMessage);
    }
}

public class ToYards : IDistance
{
    private double _yards;
    private double _meters;

    public void Calculate(double meters)
    {
        _meters = meters;
        _yards = meters * 1.0936133d;
    }

    public string CreateAnswerMessage()
    {
        return $"{_meters} meters is {_yards} yards.";
    }
}

public class ToMeters : IDistance
{
    private double _yards;
    private double _meters;

    public void Calculate(double yards)
    {
        _yards = yards;
        _meters = yards / 1.0936133d;
    }

    public string CreateAnswerMessage()
    {
        return $"{_yards} yards is {_meters} meters.";
    }
}

public class FeetToMeters : IDistance
{
    private double _feet;
    private double _meters;

    public void Calculate(double feet)
    {
        _feet = feet;
        _meters = feet * 0.3048d;
    }

    public string CreateAnswerMessage()
    {
        return $"{_feet} feet is {_meters} meters.";
    }
}

public class MetersToFeet : IDistance
{
    private double _feet;
    private double _meters;

    public void Calculate(double meters)
    {
        _meters = meters;
        _feet = meters / 0.3048d;
    }

    public string CreateAnswerMessage()
    {
        return $"{_meters} meters is {_feet} feet.";
    }
}

ダウンロード

Answer02.zip

4.98 KB

ファイルダウンロードについて

ダウンロード

解説

　今回は第1回の解説と全く同じです。

入力メッセージを追加

　ここは問題ありませんね。

Console.WriteLine("3 : Convert meters to feet.");
Console.WriteLine("4 : Convert feet to meters.");

オブジェクト生成を追加

　オブジェクト生成部分を追加します。ここが、今回のメインですね。

public class DistanceFactory
{
    public static IDistance Create(int convertNumber)
    {
        switch (convertNumber)
        {
            case 1:
                return new ToYards();
            case 2:
                return new ToMeters();
            case 3:
                return new MetersToFeet();
            case 4:
                return new FeetToMeters();
            default:
                throw new ArgumentOutOfRangeException(
                    $"{convertNumber} is out of range.");
        }
    }
}

変換クラスを追加

　メートルをフィートに変換するクラスを追加します。

public class MetersToFeet : IDistance
{
    private double _feet;
    private double _meters;

    public void Calculate(double meters)
    {
        _meters = meters;
        _feet = meters / 0.3048;
    }

    public string CreateAnswerMessage()
    {
        return $"{_meters} meters is {_feet} feet.";
    }
}

　フィートをメートルに変換するクラスを追加します。

public class FeetToMeters : IDistance
{
    private double _feet;
    private double _meters;

    public void Calculate(double feet)
    {
        _feet = feet;
        _meters = feet * 0.3048;
    }

    public string CreateAnswerMessage()
    {
        return $"{_feet} feet is {_meters} meters.";
    }
}