Exercicio de OO pedido em sala dia 19/11/2015. - Daniel Ferreira Ramos <ramos.danielferreira@gmail.com>. Também disponivel em http://1drv.ms/1I2fozC

Circle.cs

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

namespace FormacaoTalentos.Exercise
{
    public class Circle : ResizableCircle, IGeometricObject
    {
        // Se quiser fazer com Auto property direto
        //protected double Radius { get; set; }
        private double _radius;
        public double Radius
        {
            get
            {
                return (_radius < 0.0) ? 1.0 : _radius;
            }

            set
            {
                _radius = value;
            }
        }

        public Circle(double radius) : base(radius)
        {
            this.Radius = radius;
        }

        public double GetPerimeter()
        {
            return this.Radius * 2 * Math.PI;
        }

        public double GetArea()
        {
            return Math.Pow(this.Radius, 2) * Math.PI;
        }
    }
}

IGeometricObject.cs

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

namespace FormacaoTalentos.Exercise
{
    interface IGeometricObject
    {
        double GetPerimeter();
        double GetArea();
    }
}

IResizable.cs

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

namespace FormacaoTalentos.Exercise
{
    interface IResizable
    {
        void Resize(int percent);
    }
}

Program.cs

using FormacaoTalentos.Exercise;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace FormacaoTalentos
{
    class Program
    {
        static void Main(string[] args)
        {
            IGeometricObject a = new Circle(-1.0);
            Console.WriteLine(a.GetPerimeter());
            Console.WriteLine(a.GetArea());

            IGeometricObject o = new Circle(0.0);
            Console.WriteLine(o.GetPerimeter());
            Console.WriteLine(o.GetArea());


            Circle c = new Circle(10);
            Console.WriteLine(c.GetPerimeter());
            Console.WriteLine(c.GetArea());
        }
    }
}

ResizableCircle.cs

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

namespace FormacaoTalentos.Exercise
{
    public class ResizableCircle : IResizable
    {

        public ResizableCircle(double radius)
        {
            
        }

        public void Resize(int percent)
        {

        }
    }
}