Nullable variable : Nulllable « Data Types « C# / C Sharp

1. C# / C Sharp
2. Data Types
3. Nulllable

Nullable variable

  


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

public class Vector {
    public double? R = null;
    public double? Theta = null;

    public double? ThetaRadians {
        get {
            return (Theta * Math.PI / 180.0);
        }
    }

    public Vector(double? r, double? theta) {
        if (r < 0) {
            r = -r;
            theta += 180;
        }
        theta = theta % 360;

        R = r;
        Theta = theta;
    }

    public static Vector operator +(Vector op1, Vector op2) {
        try {
            double newX = op1.R.Value * Math.Sin(op1.ThetaRadians.Value)
               + op2.R.Value * Math.Sin(op2.ThetaRadians.Value);
            double newY = op1.R.Value * Math.Cos(op1.ThetaRadians.Value)
               + op2.R.Value * Math.Cos(op2.ThetaRadians.Value);

            double newR = Math.Sqrt(newX * newX + newY * newY);
            double newTheta = Math.Atan2(newX, newY) * 180.0 / Math.PI;

            return new Vector(newR, newTheta);
        } catch {
            return new Vector(null, null);
        }
    }

    public static Vector operator -(Vector op1) {
        return new Vector(-op1.R, op1.Theta);
    }

    public static Vector operator -(Vector op1, Vector op2) {
        return op1 + (-op2);
    }

    public override string ToString() {
        string rString = R.HasValue ? R.ToString() : "null";
        string thetaString = Theta.HasValue ? Theta.ToString() : "null";

        return string.Format("({0}, {1})", rString, thetaString);
    }
}

class Program {
    public static void Main(string[] args) {
        Vector v1 = GetVector("vector1");
        Vector v2 = GetVector("vector1");
        Console.WriteLine("{0} + {1} = {2}", v1, v2, v1 + v2);
        Console.WriteLine("{0} - {1} = {2}", v1, v2, v1 - v2);
        Console.ReadKey();
    }

    public static Vector GetVector(string name) {
        Console.WriteLine("Input {0} magnitude:", name);
        double? r = GetNullableDouble();
        Console.WriteLine("Input {0} angle (in degrees):", name);
        double? theta = GetNullableDouble();
        return new Vector(r, theta);
    }

    public static double? GetNullableDouble() {
        double? result;
        string userInput = Console.ReadLine();
        try {
            result = double.Parse(userInput);
        } catch {
            result = null;
        }
        return result;
    }
}

   
  

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