How to reset a timer in C#?

Question

There are three Timer classes that I am aware of, System.Threading.Timer, System.Timers.Timer, and System.Windows.Forms.Timer, but none of these have a .Reset() function which would reset the current elapsed time to 0.

Is there a BCL class that has this functionality? Is there a non-hack way of doing it? (I thought perhaps changing the time limit on it might reset it) Thought on how hard it would be to reimplement a Timer class that had this functionality, or how to do it reliably with one of the BCL classes?

Answer 1

I always do ...

myTimer.Stop();
myTimer.Start();

... is that a hack? :)

Per comment, on Threading.Timer, it's the Change method ...

dueTime Type: System.Int32 The amount of time to delay before the invoking the callback method specified when the Timer was constructed, in milliseconds. Specify Timeout.Infinite to prevent the timer from restarting. Specify zero (0) to restart the timer immediately.

Answer 2

All the timers have the equivalent of Start() and Stop() methods, except System.Threading.Timer.

So an extension method such as...

public static void Reset(this Timer timer)
{
  timer.Stop();
  timer.Start();
}

...is one way to go about it.

Answer 3

For System.Timers.Timer, according to MSDN documentation, http://msdn.microsoft.com/en-us/library/system.timers.timer.enabled.aspx:

If the interval is set after the Timer has started, the count is reset. For example, if you set the interval to 5 seconds and then set the Enabled property to true, the count starts at the time Enabled is set. If you reset the interval to 10 seconds when count is 3 seconds, the Elapsed event is raised for the first time 13 seconds after Enabled was set to true.

So,

    const double TIMEOUT = 5000; // milliseconds

    aTimer = new System.Timers.Timer(TIMEOUT);
    aTimer.Start();     // timer start running

    :
    :

    aTimer.Interval = TIMEOUT;  // restart the timer

Answer 4

You could write an extension method called Reset(), which

• calls Stop()-Start() for Timers.Timer and Forms.Timer
• calls Change for Threading.Timer

Answer 5

I just assigned a new value to the timer:

mytimer.Change(10000, 0); // reset to 10 seconds

It works fine for me.

at the top of the code define the timer: System.Threading.Timer myTimer;

if (!active)
    myTimer = new Timer(new TimerCallback(TimerProc));

myTimer.Change(10000, 0);
active = true;

private void TimerProc(object state)
{
    // The state object is the Timer object.
    var t = (Timer)state;

    t.Dispose();
    Console.WriteLine("The timer callback executes.");
    active = false;
    
    // Action to do when timer is back to zero
}

Answer 6

For a Timer (System.Windows.Forms.Timer).

The .Stop, then .Start methods worked as a reset.

Answer 7

You can do timer.Interval = timer.Interval

Answer 8

I do the following. Disposing the timer and initializing it again. But this will erase any event you attached to this timer.

timer.Dispose();
timer = new System.Timers.Timer();

Answer 9

Other alternative way to reset the windows.timer is using the counter, as follows:

int timerCtr = 0;
Timer mTimer;

private void ResetTimer() => timerCtr = 0;
private void mTimer_Tick()
{
    timerCtr++;
    // Perform task
}  

So if you intend to repeat every 1 second, you can set the timer interval at 100ms, and test the counter to 10 cycles.

This is suitable if the timer should wait for some processes those may be ended at the different time span.

Answer 10

Sorry for arriving late with the answer but it might be helpful. If you need a "watchdog" kind of a timer that will start counting from zero again, use the System.Threading.Timer class and Change method.

Below is a code snippet that will only call test method if there is no interruption from the user for more than 3 seconds:

using System;
using System.Threading;
namespace WatchdogExample
{
    internal class Watchdog
    {
        static void Main(string[] args)
        {
            Timer t = new Timer(timer_callback, null, 3000, Timeout.Infinite);
            while (true)
            {
                Console.ReadLine();
                t.Change(3000, Timeout.Infinite);
            }
        }
        static void timer_callback(object state)
        {
            Console.WriteLine("test");
        }
    }
}

Answer 11

i do this

//Restart the timer
queueTimer.Enabled = true;