I needed a 5 minute countdown for a project I was working on so I hacked this up, It does nothing more and nothing less. Figured I would post it while I was here to save someone else the trouble. (Not that it's in anyway difficult to do.)

Comments
Nice!
using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;

namespace CountDownTimers
{
    public class Fivemintimer
    {
        Timer T = new Timer();

        int Minutes = 5;
        int Seconds = 0;

        public Fivemintimer()
        {
            T.Interval = 1000;
            T.Tick += new EventHandler(T_Tick);
        }

        public delegate void onTimerFinishedDelegate();
        public event onTimerFinishedDelegate onTimerFinished;

        public delegate void onTimerChanged(FIVETimerEventArgs args);
        public event onTimerChanged onTimerTick;

        void T_Tick(object sender, EventArgs e)
        {
            if (Minutes == 0 && Seconds == 0)
            {
                T.Stop();

                if (onTimerFinished != null)
                {
                    onTimerFinished();
                }
            }
            else
            {

                if (Seconds == 0)
                {
                    Seconds = 59;

                    Minutes--;
                }
                else
                {
                    Seconds--;
                }

            }

            if (onTimerTick != null)
            {
                onTimerTick(new FIVETimerEventArgs(Minutes, Seconds));
            }

        }

        public void PlayPause()
        {
            if (T.Enabled)
            {
                T.Stop();
            }
            else
            {
                T.Start();
            }
        }

        public void Reset()
        {

            Minutes = 5;
            Seconds = 0;
        }

        public bool Enabled
        {
            get
            {
                return T.Enabled;
            }
        }


    }

    public class FIVETimerEventArgs : EventArgs
    {

        public string TimeLeft;

        public FIVETimerEventArgs(int min, int sec)
        {
            string S;
            if (sec < 10)
            {
                S = "0" + sec.ToString();
            }
            else
            {

                S = sec.ToString();
            }

            TimeLeft = min.ToString() + ":" + S;
        }

    }
}

You'd think 1000 would accurately represent 1 second. I found that if I compared ticks to the starting tick value that my elapsed time timer would occationally jump 2 seconds using 1000. By the time 5 minutes elapsed, you'd probably be off by about 5 seconds using this minute second process. On a timer that is dependent on human reactions, this code is fine, it'll be at most 5 seconds slow and if you use the minute/second method used here to display your time, you'd never have a clue your time is at all off.
(Since I didn't use UTCNow, my timer could jump an hour ahead or backwards. Wasn't thinking of anyone playing with code at 2AM on two special days a year when I wrote it and didn't set up the timer to display hours so you'd see 60+ minutes going forward.)

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