using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace Calc_Area_and_Perimeter

{

    internal class Program

    {

        static void Main(string[] args)

        {

            double length, width;

            Console.Write("Length: ");

            length = double.Parse(Console.ReadLine());

            Console.Write("Width: ");

            width = double.Parse(Console.ReadLine());

            double[] nums = CalculateAreaAndPerimeter(ref length, ref width);

            Console.WriteLine("Area = " + nums[0]);

            Console.WriteLine("Perimeter = " + nums[1]);

        }

        static double [] CalculateAreaAndPerimeter(ref double length, ref double width)

        {

            double area = length * width;

            double perimeter = width * 2 + length * 2;

            double[] nums = { area, perimeter };

            return nums;

        }

    }

}

​