Stopwatch class capable of calculating and displaying the elapsed time between the Start() and Stop() functions. This can be added to any project to easily test the speed of different functions against eachother.

Stopwatch.cs

using System;

namespace SimpleStopwatch
{
    public class Stopwatch
    {
        private DateTime _Start;

        public TimeSpan Time { get { return _Time; } }
        private TimeSpan _Time;

        public Stopwatch()
        {
            this._Start = DateTime.Now;
            this._Time = TimeSpan.Zero;
        }

        public void Start()
        {
            this._Start = DateTime.Now;
        }

        public void Stop()
        {
            this._Time = DateTime.Now - _Start;
        }

        public override string ToString()
        {
            return _Time != TimeSpan.Zero ? _Time.Hours.ToString("00") + "h:" 
                + _Time.Minutes.ToString("00") + "m:" + _Time.Seconds.ToString("00") 
                + "s:" + _Time.Milliseconds.ToString("0000") + "ms" : ThrowNullTimeException();
        }

        public string ToSeconds()
        {
            return _Time != TimeSpan.Zero ? _Time.TotalSeconds.ToString("#.###") + "s" : ThrowNullTimeException();
        }
        
        public string ToMinutes()
        {
            return _Time != TimeSpan.Zero ? _Time.TotalMinutes.ToString("#.##") + "m" : ThrowNullTimeException();
        }

        public string GetResultString()
        {
            return _Time != TimeSpan.Zero ? "Elapsed Time: " + _Time.Minutes.ToString("00") + "m : " + _Time.Seconds.ToString("00") + "s : " + _Time.Milliseconds.ToString("000") + "ms" : ThrowNullTimeException();
        }

        public void PrintResult()
        {
            Console.WriteLine(GetResultString());
        }

        private string ThrowNullTimeException()
        {
            throw new Exception("Stopwatch was not stopped prior to requesting ToString(). "
                + "TimeSpan is null, please call Stop() before calling ToString().");
        }
    }
}