I am new to C# world. I am attempting to calculate time taken by a algorithum for the purpose of comparison. Following code measures the elapsed time from when a subroutine is called until the subroutine returns to the main program.This example is taken from "Data structures through C#" by Michael McMillan. After running this program the output is Time=0, which is incorrect. The program appears to be logically correct. Can anybody help me. Following is the code

using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
namespace Chap1
{
class Program
{
    static void Main(string[] args)
    {
        int num1 = 100;
        int num2 = 200;
        Console.WriteLine("num1: " + num1);
        Console.WriteLine("num2: " + num2);
        Swap<int>(ref num1, ref num2);
        Console.WriteLine("num1: " + num1);
        Console.WriteLine("num2: " + num2);
        string str1 = "Sam";
        string str2 = "Tom";
        Console.WriteLine("String 1: " + str1);
        Console.WriteLine("String 2: " + str2);
        Swap<string>(ref str1, ref str2);
        Console.WriteLine("String 1: " + str1);
        Console.WriteLine("String 2: " + str2);
        Console.ReadKey();
    }

    static void Swap<T>(ref T val1, ref T val2)
    {
        T temp;
        temp = val1;
        val1 = val2;
        val2 = temp;
    }
}
class Timing
    {
        TimeSpan StartTiming;
        TimeSpan duration;
        public Timing()
        {
            StartTiming = new TimeSpan(0);
            duration = new TimeSpan(0);
        }
        public TimeSpan startTime()
        {
            GC.Collect();


     GC.WaitForPendingFinalizers();
            StartTiming = Process.GetCurrentProcess().Threads[0].UserProcessorTime;
            return StartTiming;
        }
        public void stopTime()
        {
            duration = Process.GetCurrentProcess().Threads[0].UserProcessorTime.Subtract(StartTiming);

        }
        public TimeSpan result()
        {
            return duration;
        }
    }
}