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I'm trying to figure out how to reduce an integer every second. Everything suggests things that are many, many lines long, and are explaining things in a generic, interchangeable way. So far I've set it up as...
public int timer = 180;
public Text timerCounterText;
// Use this for initialization
void Start ()
{
timerCounterText.text = "Time Left: " + timer.ToString();
}
Now I have no idea how to actually make the integer decrease by one each second, I don't want any suggestions of a potentially better way to do it unless there's no way to do it from what I have here.
I just want a simple, in as few lines as possible way to reduce my timer integer by 1 each second, as the way I have done this is the only way I understand how to do this so far.
Sorry if this is too much to ask, I just want a script I can understand, not just one that works best, as I'm just a student, not making a product.
I have worked a lot with timers in C# (a HELL of a lot - I used to develop software for a Sports Timing company).
There are a few ways of doing it. Some more accurate than others.
The simplest - which is the way you're looking at would be like so:
Set your total seconds in a private field:
private int _secondsRemaining = 180; // 3 minutes
Create a Timer stored in a private field:
private System.Timers.Timer _countdownTimer;
Create a StartTimer() method. Initialize the _countdownTimer, and create an Event Handler for when the timer ticks - this is what happens when it "reaches 0"/fires/whatever you want to call it:
public void StartTimer()
{
_countdownTimer = new System.Timers.Timer(1000); // 1000 is the number of milliseconds
// 1000ms = 1 second
// Set a handler for when the timer "ticks"
// The "Tick" event will be fired after 1 second (as we've set it)
// The timer will loop, though and keep firing until we stop it
// Or unless it is set to not automatically restart
_countdownTimer.Tick += OnTimer_Tick;
// Start the timer!
_countdownTimer.Start();
}
You will need to call StartTimer() from somewhere in your program, otherwise it won't ever start (obviously) - you can do this from the constructor or a button click etc.
Now, create an Event Handler for when the timer ticks. In this, decrement (take 1 from) the _secondsRemaining value; and then display it in your timerCounterText label:
// This is what gets fired when the timer "reaches 0"
private void OnTimer_Tick(object sender, ElapsedEventArgs e)
{
_secondsRemaining--; // the same as "_secondsRemaining = secondsRemaining -1"
timerCounterText.Text = string.Format("Time Remaining: {0} seconds",
_secondsRemaining);
}
This is a nice and easy way to make a countdown timer.
The drawback is, that the timer doesn't fire EXACTLY every second, so you may notice a little bit of drift.
Like I mentioned; depending on the accuracy you need, there are other ways I have used. It depends on what the timer's being used for.
WAIT! There's more!
What would also be useful (if you need it), is, when the _secondsRemaining reaches 0 to stop the timer.
Create a StopTimer() method:
private void StopTimer()
{
if (_countdownTimer != null)
{
_countdownTimer.Tick -= OnTimer_Tick;
_countdownTimer.Stop();
_countdownTimer.Dispose();
_countdownTimer = null;
}
}
You could also use this method when you want to stop the timer manually from a button click or whatever.
Notice the null check, and the code within it. The null check is just for damage limitation in case the _countdownTimer hasn't been initialized etc. and to stop your program bombing out if so.
The code within the if check unsubscribes from the Tick event, stops the timer (obviously), and then gets rid of the _countdownTimer - you don't need to; but you will need to unsubscribe & stop it...
If we called StartTimer() again and initialized the timer, we'd be adding another subscription to the Tick event - this would cause the OnTimer_Tick method to be called twice every time the _countdownTimer fires (and so on and so forth).
Now, in your OnTimer_Tick handler, where we decrement the value of _secondsRemaining - check after, if it is less or equal to 0:
private void OnTimer_Tick(object sender, ElapsedEventArgs e)
{
_secondsRemaining--; // decrement the _secondsRemaining as before
if (_secondsRemaining <= 0)
{
StopTimer(); // This will stop the timer when the _secondsRemaining
// reach 0 (or go below - it shouldn't)
// You can also add in other stuff to happen at 0
// such as "Ending the game", as you described
}
// Display the time remaining, still - as before
timerCounterText.Text = string.Format("Time Remaining: {0} seconds",
_secondsRemaining);
}
Where the check for _secondsRemaining <= 0 is, you could also add your own methods for other things to happen - such as Ending your game as you asked in your question :)
I won't go into any more detail; and I'll let you figure it out - but you could even add in ResetTimer() methods, so you could start the timer again.
I hope this helps - any questions or any other ways to do timers you need; just ask.
I would advise a separate thread doing a decrease in the integer. I would do this with a while loop
public event SecondHappenedEventHandler SecondHappened;
public delegate void SecondHappenedEventHandler(int second);
private int timer = 180;
Public Void Start()
{
timer = 180;
Thread th = New Thread(New ThreadStart(Monitor);
th.Start();
}
Private Void Monitor()
{
While (timer != 0)
{
timer--;
SecondHappened(timer);
Thread.Sleep(1000); //This is milliseconds
}
}
My C# is a little rusty since I have been doing VB more recently for work. Then Add a raiseevent in that class that passes back the integer to the the other class. So your other class would make an instance of this class and have an event that gets the second passed back and display it to the end user.
public Text timerCounterText;
private TimerClass timer;
// Use this for initialization
void Start ()
{
timer.Start
}
private void SecondHappened(int timerBack)
{
timerCounterText.text = "Time Left: " + timerBack.ToString();
}
You can use one of the few Timer classes in .NET in order to get your program do stuff in regular intervals. There's usually one type of timer class that is appropriate for a given situation depending on your app type(i.e. Windows, Console, Service...etc)
Since you are after a simple example, you can have a look at the System.Timers.Timer class:
Generates an event after a set interval, with an option to generate recurring events.
Example of it's usage in a console application (P.S. If you have Windows Forms apps, you probably don't want to use it in this way):
int _countDown = 180;
void Start()
{
var timer = new System.Timers.Timer(1000); // Duration in milliseconds
timer.Elapsed += async ( sender, e ) => await HandleTimer();
timer.Start();
}
void HandleTimer()
{
_countDown--;
Console.WriteLine("Time Left: {0}", _countDown);
}
If you work in WF (Windows Forms), I suggest using a Timer. Create a timer control, set it's interval to 1000 (milliseconds), and in your start function just enable it:
void Start ()
{
timer1.Enabled = true;
timerCounterText.text = "Time Left: " + timer.ToString();
}
Now, a double click on the timer should create a timer_tick event. Use it like that:
void timer_Tick(object sender, EventArgs e)
{
timerCounterText.text = "Time Left: " + (--timer).ToString();
}
Then it should reduce the timer by 1 every second. Of course you should check when it arrives to 0, and then set timer1.Enabled to false.
Using the Decrement Operator --
If you wanted to decrement it prior to the value being updated, you could use the decrement operator --:
void Start ()
{
// This will decrement the timer by 1
timer--;
// Output the value
timerCounterText.Text = "Time Left: " + timer.ToString();
}
You could also accomplish this same thing inline using prefix notation, which will update the value prior to using it :
void Start ()
{
// Decrement your count and output it
timerCounterText.Text = "Time Left: " + (--timer).ToString();
}
Cleaning Up Your Output
You can clean up your output a bit more by using the String.Format() method as well :
void Start ()
{
// Decrement your count and output it
timerCounterText.Text = String.Format("Time Left: {0}",--timer);
}
or if you are using C#, you can take advantage of String Interpolation :
void Start ()
{
// Decrement your count and output it
timerCounterText.Text = $"Time Left: {--timer}";
}
Making Your Timer Tick
Assuming that you are using a Timer class, you can set it's Tick event to be triggered as a certain interval. This is what you would use to actually decrement your value and output it to the user :
// Define a timer
Timer countDown = new Timer();
// Sets the timer interval to 1 seconds.
countDown.Interval = 1000;
// Call the tick event every second
countDown.Tick += new EventHandler(Tick);
// Start your timer
countDown.Start();
and your Tick event would look like this :
private static void Tick(Object myObject,EventArgs myEventArgs)
{
// Check if your timer has run out
if(countDown <= 0)
{
// Timer has run out, handle accordingly
countDown.Stop();
}
else
{
// Otherwise output and decrement
String.Format("Time Left: {0}",--timer);
}
}
Related
I want to execute a function every 60 seconds in C#. I could use the Timer class like so:
timer1 = new Timer();
timer1.Tick += new EventHandler(timer1_Tick);
timer1.Interval = 60 * 1000; // in miliseconds
timer1.Start();
Question is I have a long running process. Occasionally it make take several minutes. Is there a way to make the timer smart so if the function is already being executed then it should skip that cycle and come back 60 seconds later and if again it is in execution then again skip and come back 60 seconds later.
I would suggest you to have a class member variable bool variable with value false.
then in click event return if its true at the beginning.
and then set it to true, so that it will tell you that its currently in execution.
then write your logic.
and then once done finally set it to false again.
code will look like this.
private bool isRunning = false;
private void timer1_Tick(object sender, EventArgs e)
{
if (isRunning)
{
return;
}
isRunning = true;
try
{
... //Do whatever you want
}
finally
{
isRunning = false;
}
}
The modern and most clean way to do this is using Microsoft's new Period Timer:
var timer = new PeriodicTimer(TimeSpan.FromSeconds(n));
while (await timer.WaitForNextTickAsync())
{
//Business logic
}
If you need to abort such a ticker, you can pass a cancellation token to the WaitForNextTickAsync method.
Another advantage is this:
The PeriodicTimer behaves like an auto-reset event, in that multiple ticks are coalesced into a single tick if they occur between calls to WaitForNextTickAsync(CancellationToken). Similarly, a call to Dispose() will void any tick not yet consumed. WaitForNextTickAsync(CancellationToken) may only be used by one consumer at a time, and may be used concurrently with a single call to Dispose().
Source: https://learn.microsoft.com/en-us/dotnet/api/system.threading.periodictimer.waitfornexttickasync?source=recommendations&view=net-7.0#remarks
If you need more granularity (like "always at 10 am", use something like https://github.com/HangfireIO/Cronos
Use a timer, set it to 60 second
On Event:
try
Stop timer
Do logic
catch
What ever fail recovery
finally
Start the timer
Logic is run 60 seconds after last finish.
You can use a Stopwatch inside a loop: start the stopwatch, after 60 second call the function, reset the stopwatch, start the loop again.
I have a service written in C# (.NET 1.1) and want it to perform some cleanup actions at midnight every night. I have to keep all code contained within the service, so what's the easiest way to accomplish this? Use of Thread.Sleep() and checking for the time rolling over?
I wouldn't use Thread.Sleep(). Either use a scheduled task (as others have mentioned), or set up a timer inside your service, which fires periodically (every 10 minutes for example) and check if the date changed since the last run:
private Timer _timer;
private DateTime _lastRun = DateTime.Now.AddDays(-1);
protected override void OnStart(string[] args)
{
_timer = new Timer(10 * 60 * 1000); // every 10 minutes
_timer.Elapsed += new System.Timers.ElapsedEventHandler(timer_Elapsed);
_timer.Start();
//...
}
private void timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
// ignore the time, just compare the date
if (_lastRun.Date < DateTime.Now.Date)
{
// stop the timer while we are running the cleanup task
_timer.Stop();
//
// do cleanup stuff
//
_lastRun = DateTime.Now;
_timer.Start();
}
}
Check out Quartz.NET. You can use it within a Windows service. It allows you to run a job based on a configured schedule, and it even supports a simple "cron job" syntax. I've had a lot of success with it.
Here's a quick example of its usage:
// Instantiate the Quartz.NET scheduler
var schedulerFactory = new StdSchedulerFactory();
var scheduler = schedulerFactory.GetScheduler();
// Instantiate the JobDetail object passing in the type of your
// custom job class. Your class merely needs to implement a simple
// interface with a single method called "Execute".
var job = new JobDetail("job1", "group1", typeof(MyJobClass));
// Instantiate a trigger using the basic cron syntax.
// This tells it to run at 1AM every Monday - Friday.
var trigger = new CronTrigger(
"trigger1", "group1", "job1", "group1", "0 0 1 ? * MON-FRI");
// Add the job to the scheduler
scheduler.AddJob(job, true);
scheduler.ScheduleJob(trigger);
A daily task? Sounds like it should just be a scheduled task (control panel) - no need for a service here.
Does it have to be an actual service? Can you just use the built in scheduled tasks in the windows control panel.
The way I accomplish this is with a timer.
Run a server timer, have it check the Hour/Minute every 60 seconds.
If it's the right Hour/Minute, then run your process.
I actually have this abstracted out into a base class I call OnceADayRunner.
Let me clean up the code a bit and I'll post it here.
private void OnceADayRunnerTimer_Elapsed(object sender, ElapsedEventArgs e)
{
using (NDC.Push(GetType().Name))
{
try
{
log.DebugFormat("Checking if it's time to process at: {0}", e.SignalTime);
log.DebugFormat("IsTestMode: {0}", IsTestMode);
if ((e.SignalTime.Minute == MinuteToCheck && e.SignalTime.Hour == HourToCheck) || IsTestMode)
{
log.InfoFormat("Processing at: Hour = {0} - Minute = {1}", e.SignalTime.Hour, e.SignalTime.Minute);
OnceADayTimer.Enabled = false;
OnceADayMethod();
OnceADayTimer.Enabled = true;
IsTestMode = false;
}
else
{
log.DebugFormat("Not correct time at: Hour = {0} - Minute = {1}", e.SignalTime.Hour, e.SignalTime.Minute);
}
}
catch (Exception ex)
{
OnceADayTimer.Enabled = true;
log.Error(ex.ToString());
}
OnceADayTimer.Start();
}
}
The beef of the method is in the e.SignalTime.Minute/Hour check.
There are hooks in there for testing, etc. but this is what your elapsed timer could look like to make it all work.
As others already wrote, a timer is the best option in the scenario you described.
Depending on your exact requirements, checking the current time every minute may not be necessary.
If you do not need to perform the action exactly at midnight, but just within one hour after midnight, you can go for Martin's approach of only checking if the date has changed.
If the reason you want to perform your action at midnight is that you expect a low workload on your computer, better take care: The same assumption is often made by others, and suddenly you have 100 cleanup actions kicking off between 0:00 and 0:01 a.m.
In that case you should consider starting your cleanup at a different time. I usually do those things not at clock hour, but at half hours (1.30 a.m. being my personal preference)
I would suggest that you use a timer, but set it to check every 45 seconds, not minute. Otherwise you can run into situations where with heavy load, the check for a particular minute is missed, because between the time the timer triggers and the time your code runs and checks the current time, you might have missed the target minute.
You can also try the TaskSchedulerLibrary here http://visualstudiogallery.msdn.microsoft.com/a4a4f042-ffd3-42f2-a689-290ec13011f8
Implement the abstract class AbstractScheduledTask and call the ScheduleUtilityFactory.AddScheduleTaskToBatch static method
For those that found the above solutions not working, it's because you may have a this inside your class, which implies an extension method which, as the error message says, only makes sense on a non-generic static class. Your class isn't static. This doesn't seem to be something that makes sense as an extension method, since it's acting on the instance in question, so remove the this.
Try this:
public partial class Service : ServiceBase
{
private Timer timer;
public Service()
{
InitializeComponent();
}
protected override void OnStart(string[] args)
{
SetTimer();
}
private void SetTimer()
{
if (timer == null)
{
timer = new Timer();
timer.AutoReset = true;
timer.Interval = 60000 * Convert.ToDouble(ConfigurationManager.AppSettings["IntervalMinutes"]);
timer.Elapsed += new ElapsedEventHandler(timer_Elapsed);
timer.Start();
}
}
private void timer_Elapsed(object source, System.Timers.ElapsedEventArgs e)
{
//Do some thing logic here
}
protected override void OnStop()
{
// disposed all service objects
}
}
I'm working on a very basic program where I want a ball to follow a parabolic curve. My idea is to set a timer to tick with a certain interval and set the time as an variable which I use in my equation which will also be my x-value.
I've created an event timer_Tick. How can I increase the value of X each time the timer ticks?
You need to create class field (e.g. elapsedTime) to store value between event handler calls:
private int elapsedTime; // initialized with zero
private Timer timer = new System.Windows.Forms.Timer();
public static int Main()
{
timer.Interval = 1000; // interval is 1 second
timer.Tick += timer_Tick;
timer.Start();
}
private void timer_Tick(Object source, EventArgs e) {
elapsedTime++; // increase elapsed time
DrawBall();
}
This isn't a direct answer to your question - but you might find it helpful.
It's a completely different way to go that uses Reactive Extensions (create a console app and add Nuget package "Rx-Testing") and also demonstrates how you can virtualize time which can be helpful for testing purposes. You can control time as you please!
using System;
using System.Reactive.Concurrency;
using System.Reactive.Linq;
namespace BallFlight
{
class Program
{
static void Main()
{
var scheduler = new HistoricalScheduler();
// use this line instead if you need real time
// var scheduler = Scheduler.Default;
var interval = TimeSpan.FromSeconds(0.75);
var subscription =
Observable.Interval(interval, scheduler)
.TimeInterval(scheduler)
.Scan(TimeSpan.Zero, (acc, cur) => acc + cur.Interval)
.Subscribe(DrawBall);
// comment out the next line of code if you are using real time
// - you can't manipulate real time!
scheduler.AdvanceBy(TimeSpan.FromSeconds(5));
Console.WriteLine("Press any key...");
Console.ReadKey(true);
subscription.Dispose();
}
private static void DrawBall(TimeSpan t)
{
Console.WriteLine("Drawing ball at T=" + t.TotalSeconds);
}
}
}
Which gives the output:
Drawing ball at T=0.75
Drawing ball at T=1.5
Drawing ball at T=2.25
Drawing ball at T=3
Drawing ball at T=3.75
Drawing ball at T=4.5
Press any key...
private int myVar= 0;//private field which will be incremented
void timer_Tick(object sender, EventArgs e)//event on timer.Tick
{
myVar += 1;//1 or anything you want to increment on each tick.
}
First the variable needs to be declared outside of any method, which is 'class scope'
In the tick event method, you can then just x = x + value, or x += value. Note that the tick event doesn't tell you how many ticks! So you're likely to need a second variable to keep track of this too.
I have a function (say foo())that will be called from time to time with a variable interval. When it is called, it checks the time and takes an action accordingly.
I have done this in the following way:
A Forms.Timer object invokes the function when required
A Diagnostics.Stopwatch object is used within the function for the purpose of determining the time and deciding what to do.
However I have the following problem: when foo() is called by Timer's callback, the ElapsedMilliseconds value of stopwatch object is usually lower than expected. For example, timer is set to 1000 so after 1000 ms foo() is called, but within foo() body ElapsedMilliseconds return 900 therefore foo behaves as if the elapsed time was 900 (although it should take the action A because 1000 ms actually elapsed, it does not)
How can I synchronize timer and stopwatch in such case that ElapsedMilliseconds have a consistent value with timer?
EDIT: Some Code
Some sample code to explain what is my problem:
//foo is the function that is called by timer's callback
public void foo()
{
//Let's see what time it is:
long currentTime = stopwatch.ElapsedMilliseconds();
Item = getCurrentItem(currentTime);
Item.Draw();
}
//this is the callback of timer
private void timer1_Tick(object sender, EventArgs e)
{
//set the timer for next time
timer1.Interval = Intervals[periodIdx++];
foo();
}
This is supposed to draw something else each time when an interval is completed, however since ElapsedMilliseconds return an earlier value than timer claims, although the interval is over, next item isn't drawn
You get the big difference because you start the timer somewhere within the 1/64 second interval. You'll get better results with this:
private void StartTimers() {
int tick = Environment.TickCount;
while (Environment.TickCount == tick) Thread.Sleep(0);
timer1.Enabled = true;
stopwatch.Start();
}
Where the while() loop improves the odds that the timer gets started at the start of a 1/64 timer tick. Just improves, no guarantees. And you can't do anything about the Tick event firing late, it entirely depends on the responsiveness of your UI thread. It is however always late. Don't use this code, write your code so you don't care that these timers are not in sync. You may have to reduce the timer's Interval to accomplish that, it isn't clear from the question.
You aren't going to have much success with this approach. You're not starting each timer at the exact same time and you're not checking them at the exact same time (there some passage of time between the Timer firing it's event and your code querying the Stopwatch).
Pick a single timer and base everything off of it if you want things in sync. For example, if you want to go with the Forms.Timer, in your event handler for it just increment a counter variable - that will tell you how many times your handler has been called and, effectively, how much time the Forms.Timer says has passed. Here's an example (I'll leave it to you to handle the case of the timer ticking long enough that the counter exceeds long.MaxValue)
public void foo()
{
Item = getCurrentItem(totalElapsed);
Item.Draw();
}
long totalElapsed = 0;
private void timer1_Tick(object sender, EventArgs e)
{
totalElapsed += timer1.Interval;
//set the timer for next time
timer1.Interval = Intervals[periodIdx++];
foo();
}
I am using a DispatcherTimer to perform a count down before triggering the release on a camera. The UpdateCountdown method is used to change the image displayed to the user before the camera fires. Rather than having the TakePicture method execute immediately, I would like have a slight delay after the counter reaches zero and the last image is displayed.
The code shown below results in the pause occurring at the _countdown = 1 point. While the final image displays and TakePicture() fires almost simultaneously (I think TakePicture happens first).
_countdownTimer = new DispatcherTimer();
_countdownTimer.Interval = TimeSpan.FromSeconds(1);
_countdownTimer.Tick += new EventHandler(delegate(object s, EventArgs a)
{ UpdateCountdown(); } );
_countdownTimer.Tick += new EventHandler(delegate(object s, EventArgs a)
{if (_countdown == _countdownMax)
{
System.Threading.Thread.Sleep(2000); // Slight delay before taking picture
Camera.TakePicture();
} });
}
public void StartCountdown()
{
if (doCount)
{
doCount = false;
UpdateCountdown();
_countdownTimer.Start();
}
}
private void UpdateCountdown()
{
_countdown--;
CountdownImage = _countDownImages[_countdown]; // Data bound to Image Control
if (_countdown == 0)
{
_countdown = _countdownMax;
_countdownTimer.Stop();
doCount = true;
}
What am I not taking into account with my timing?
The UI does not update immediately when you change control properties - it only updates when the thread becomes idle (that is, after all your event handlers finish executing).
Thread.Sleep blocks the thread, the event handlers don't finish executing and UI isn't redrawn.
You have to either use another timer (start a new timer on the last tick of the existing timer and call TakePicture on teh new timer's tick) or, even better, use the last tick of the existing timer - update UI when (_countdown <= _countdownMax), take picture when (_countdown == _countdownMax + 1).
Why not just make your display always show 1 less than the number of seconds remaining. That way when you get to zero, (obviously with a Math.Max(0, _countdown) to prevent showing -1) it will seem like the time has run out even though there's one more second to go.
Edit: What I meant to imply but did not state - was that you could then just have one Tick handler and not use Sleep at all which will just wind up blocking the UI anyway which will probably block your UI from updating.
I don't think that events guarantee that event handlers are triggered in the order that they are registered. Try
_countdownTimer.Tick += new EventHandler(delegate(object s, EventArgs a)
{
UpdateCountdown();
if (_countdown == _countdownMax)
{
System.Threading.Thread.Sleep(2000); // Slight delay before taking picture
Camera.TakePicture();
}
});
}