Develop Reference

How to get Timespan in Milliseconds

I want to get the timespan in milliseconds by comparing two timestamps with DateTime.Now and the previous DateTime. I want to check if there is an event every 10 Milliseconds or later but the totalmilliseconds from DeltaT is like 188 or so. It is too high than I am expecting that is why I think there must be somethimg wrong. Or does everything look alright?
DateTime timestamp;
DateTime timestampAlt;
TimeSpan deltaT;
public void OnSensorChanged(SensorEvent e)
{
timestamp = System.DateTime.Now;
deltaT = timestamp - timestampAlt;
if (deltaT.TotalSeconds <= 0.01)
{
return;
}
UPDATE:
I really appreciate all of you answers but I think there is a misunderstanding (my mistake sry). So here again:
Whenever the listener recognizes an event, I want to save the timestamp and compare with the timespamp of the event before. If there is a gap of more than 10 Milliseconds between the 2 events, then I do want to know more about this new event. If not, I dont even want to continue and will leave by a return.
public void OnSensorChanged(SensorEvent e)
{
timestamp = System.DateTime.Now;
deltaT = timestamp - timestampAlt;
//int deltaT2 = timestamp.Millisecond - timestampAlt.Millisecond;
String timestampStr = timestamp.ToString("ff");
String timestampStrA = timestampAlt.ToString("ff");
if (deltaT.TotalMilliseconds <= 10 || deltaT.TotalMilliseconds <= -10) //deltaT.Seconds <= 0.01
{
return;
}
timestampAlt = timestamp;
newValue = e.Values[2];
//if (buffer[99] != 0.00)
// if last element of list is empty, add elements to buffer
if (buffer.Count <=99)
{
buffer.Add(newValue);
zeitbuffer.Add(timestamp);
}
else
{
Ableitung(DeltaBuffer(), DeltaTime()); // if last index of list is filled, do that function
}
if (e.Values[2] >= 11)
{
try
{
lock (_syncLock)
{
String z2 = newValue.ToString("0.0");
//noteInt2 = Convert.ToInt32(newValue);
try
{
_sensorTextView2.Text = string.Format("Note: {0}", z2 );
eventcounter.Add(z2);

You can use deltaT.TotalMilliseconds which expresses your delta in milliseconds. Therefore your check could be rewritten as
if (deltaT.TotalMilliseconds <= 10)
{
return;
}
10 is a value I inferred. It might not be what you need, but your question is partial. This answer addresses your particular question, however if you need to measure the duration of a task you should use the Stopwatch class, which is designed for that purpose.

if you want to fire an event every n-Seconds you can use a timer that fires an event when he elapses:
Timer timer = new Timer();
timer.Interval = 100;
timer.Elapsed += YourAmasingEvent;
timer.Start();
private void YourAmasingEvent(object sender, ElapsedEventArgs e)
{
//do something here
(sender as Timer).Start();
}
Using your code:
I guess you want to wait until the time elapsed in this case you would have to use a loop like this:
timestamp = System.DateTime.Now;
deltaT = timestamp - timestampAlt;
while(true)
{
if (deltaT.TotalSeconds <= 0.01)
{
return;
}
timestamp = System.DateTime.Now;
deltaT = timestamp - timestampAlt;
}

Multiple countdown timer in listview C# duplicating

I'm new to C#.
I'm trying to make a simple task reminder program.
The problem is, when I try to add a countdown for deadline time, it won't work correctly.
My first task countdown will be overwritten by my second task countdown, the same case when I add the third task and so on.
Here is the code of the correlating part.
private void buttonSave_Click(object sender, EventArgs e)
{
if (this.textBox_Task.Text != "")
{
listView1.View = View.Details;
ListViewItem lvwItem = listView1.Items.Add(dateTimePicker1.Text);
var day = dateTimePicker1.Value.Day;
var month = dateTimePicker1.Value.Month;
var year = dateTimePicker1.Value.Year;
endTime = new DateTime(year,month,day);
//Console.WriteLine(day);
//Console.WriteLine(month);
//Console.WriteLine(year);
//Console.WriteLine(dTime
Timer t = new Timer();
t.Interval = 500;
t.Tick += new EventHandler(t_Tick);
t.Start();
lvwItem.SubItems.Add(textBox_Task.Text);
lvwItem.SubItems.Add(textBox_Note.Text);
lvwItem.SubItems.Add("");
this.dateTimePicker1.Focus();
this.textBox_Note.Focus();
this.textBox_Task.Focus();
this.textBox_Task.Clear();
this.textBox_Note.Clear();
}
else
{
MessageBox.Show("Please enter a task to add.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Information);
this.textBox_Task.Clear();
this.textBox_Note.Clear();
}
}
void t_Tick(object sender, EventArgs e)
{
TimeSpan ts = endTime.Subtract(DateTime.Now);
var hari = dateTimePicker1.Value.Day;
Console.WriteLine(ts.Days);
for (int i = 0; i < listView1.Items.Count; i++)
{
if (ts.Days == 0)
{
listView1.Items[i].SubItems[3].Text = "DEADLINE";
}
else
{
listView1.Items[i].SubItems[3].Text = ts.ToString("d' Days 'h' Hours 'm' Minutes 's' Seconds to go'");
}
}
}
It would be much appreciated for anyone who willing to help.
Thanks in advance.
Here is the link to the picture of my problem

What you are doing now is on each button click override the current endTime object by a new one like:
endTime = new DateTime(year,month,day);
If you assign a new DateTime object to endTime. You override the old one. So the first button click will work but the second will create a new object of DateTime and assign it to endTime. Next you are calculating the time difference on that one object DateTime. So it is logic that it will be the same time for each listview items
If you want to have more than one DateTime use a List to store it in like
List<DateTime> _times = new List<DateTime>();
In the button click method add the DateTime to the list
// here add the datetime to the list
DateTime dateTime = new DateTime(year, month, day);
_times.Add(dateTime);
Next you can loop thru the dates and calculate for each one the time difference in the tick method:
foreach (var dateTime in _times)
{
TimeSpan ts = dateTime.Subtract(DateTime.Now);
// etc..
}
Also you are creating a timer for each time to calculate after 500 ms. You now can use one timer this is more efficient than crating one for each time. Just assign this in the constructor
public Form1()
{
InitializeComponent();
Timer t = new Timer();
t.Interval = 500;
t.Tick += new EventHandler(t_Tick);
t.Start();
}
Whole code
public partial class Form1 : Form
{
// This is the list where the DateTimes are stored so you can have more values
List<DateTime> _times = new List<DateTime>();
public Form1()
{
InitializeComponent();
// Assign the timer here
Timer t = new Timer();
t.Interval = 500;
t.Tick += new EventHandler(t_Tick);
t.Start();
}
private void buttonSave_Click(object sender, EventArgs e)
{
if (this.textBox_Task.Text != "")
{
listView1.View = View.Details;
ListViewItem lvwItem = listView1.Items.Add(dateTimePicker1.Text);
var day = dateTimePicker1.Value.Day;
var month = dateTimePicker1.Value.Month;
var year = dateTimePicker1.Value.Year;
// Add Datetime to list
DateTime dateTime = new DateTime(year, month, day);
_times.Add(dateTime);
lvwItem.SubItems.Add(textBox_Task.Text);
lvwItem.SubItems.Add(textBox_Note.Text);
lvwItem.SubItems.Add("");
this.dateTimePicker1.Focus();
this.textBox_Note.Focus();
this.textBox_Task.Focus();
this.textBox_Task.Clear();
this.textBox_Note.Clear();
}
else
{
MessageBox.Show("Please enter a task to add.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Information);
this.textBox_Task.Clear();
this.textBox_Note.Clear();
}
}
void t_Tick(object sender, EventArgs e)
{
// loop thru all datetimes and calculate the diffrence
foreach (var dateTime in _times)
{
// Call the specific date and subtract on it
TimeSpan ts = dateTime.Subtract(DateTime.Now);
var hari = dateTimePicker1.Value.Day;
Console.WriteLine(ts.Days);
for (int i = 0; i < listView1.Items.Count; i++)
{
if (ts.Days == 0)
{
listView1.Items[i].SubItems[3].Text = "DEADLINE";
}
else
{
listView1.Items[i].SubItems[3].Text = ts.ToString("d' Days 'h' Hours 'm' Minutes 's' Seconds to go'");
}
}
}
}
}

Should writing to the GUI be kept to a minimum?

I set up a windows form with a textbox, and two buttons, here is the click event for the buttons:
private int numberOfIterations = 1000;
private void WriteToGuiManyTimesButton_Click(object sender, EventArgs e)
{
TestTextBox.Text = string.Empty;
DateTime startTime = DateTime.Now;
for (int i = 0; i < numberOfIterations; i++)
{
TestTextBox.Text += "s";
}
DateTime endTime = DateTime.Now;
TestLabel.Text = (endTime.Ticks - startTime.Ticks).ToString();
}
private void WriteToGuiOnceButton_Click(object sender, EventArgs e)
{
TestTextBox.Text = string.Empty;
DateTime startTime = DateTime.Now;
string s = "";
for (int i = 0; i < numberOfIterations; i++)
{
s += "s";
}
TestTextBox.Text = s;
DateTime endTime = DateTime.Now;
TestLabel.Text = (endTime.Ticks - startTime.Ticks).ToString();
}
The end result is the same, the textbox has 1000 lots of "s".
However, if you prepare the string in memory, then write it to the Textbox, it only takes 9985 ticks, but if you write to the Textbox each time, it takes 1222285 ticks.
Is this because writing to TextBox.Text takes longer than writing to a variable in memory, if so, why?

The reason writing multiple times to Textbox.Text is much slower is that it is a property. The property excutes code each time it is written, potentially firing all kinds of events, such as repainting as Dmitry suggests.
Altering a string in memory simply creates a new string with the added character which seems to be much faster. Again as Dmitry suggests, using a StringBuilder would be the best choice since that would not result in a new string object being created for each modification.

It takes a lot of time for the TextBox to be re-painting in each loop itteration;
however constant string re-creating in s += "s" is not a good choice either.
Use StringBuilder as a buffer:
private void WriteToGuiManyTimesButton_Click(object sender, EventArgs e) {
DateTime startTime = DateTime.Now;
StringBuilder Sb = new StringBuilder();
for (int i = 0; i < numberOfIterations; ++i) {
Sb.Append("s");
}
TestTextBox.Text = Sb.ToString();
DateTime endTime = DateTime.Now;
TestLabel.Text = (endTime.Ticks - startTime.Ticks).ToString();
}

Windows Phone countdown app

I am trying to do two things:
On Christmas day, invoke a method whenever the page is navigated to.
After Christmas day, set the christmasDay DateTime to +1 year (so the countdown "resets").
Here is my code:
private void OnTick(object sender, EventArgs e)
{
DateTime christmasDay;
DateTime.TryParse("11/17/13", out christmasDay);
var timeLeft = christmasDay - DateTime.Now;
int x = DateTime.Now.Year - christmasDay.Year;
if (DateTime.Now > christmasDay)
{
if (x == 0)
x += 1;
christmasDay.AddYears(x);
if (DateTime.Now.Month == christmasDay.Month && DateTime.Now.Day == christmasDay.Day)
{
itsChristmas();
}
}
countdownText.Text = String.Format("{0:D2} : {1:D2} : {2:D2} : {3:D2}", timeLeft.Days, timeLeft.Hours, timeLeft.Minutes, timeLeft.Seconds);
}
When I set the date to TODAY, the "itsChristmas()" method works...but I don't actually want it to be invoked on each tick of the countdown. I tried putting it in the constructor of the page but that doesn't work. Any ideas?
The second problem is that if I set the date to a day before today, it gives me negative numbers. I don't know what is wrong with my code that this is happening. :(

Your solution is quite complex. You could solve it like this.
private void OnTick(object sender, EventArgs e)
{
var now = DateTime.Now;
var christmasDay = NextChristmas();
if (now.Date < christmasDay.Date)
{
// it's not christmas yet, nothing happens
}
if (now.Date == christmasDay.Date)
{
// it's christmas, do your thing
itsChristmas();
}
}
private DateTime NextChristmas()
{
var thisYearsChristmas = new DateTime(DateTime.Now.Year, 12, 25);
if (DateTime.Now.Date <= thisYearsChristmas.Date) return thisYearsChristmas;
return thisYearsChristmas.AddYears(1);
}
The if statemements can be written more consise but I elaborated on them to make clear what happens.

WinForm With Multiple Timers

I am writing a WinForm application to use SNMP calls either every 30 seconds or 1 minute.
I have a timer working for calling my SNMP commands, but I want to add a texbox counter that display the total time elapsed during the operation.
There are many problems I am having so here is a list:
I want my SNMP timer 'timer' to execute once before waiting the allotted time so I have it going off at 3 seconds and then changing the interval in my handler. But this sometimes makes the timer go off multiple times which is not what I want.
Every time 'timer' goes off and my SNMP calls execute my counter timer 'appTimer' becomes out of sync. I tried a work around where I check if it is in the other handler and then just jump the timer to its appropriate time. Which works but I feel this is making it too complicated.
My last issue, that I know of, happens when I stop my application using my stop button which does not completely exit the app. When I go to start another run the time between both timers is becomes even greater and for some reason my counting timer 'appTimer' starts counting twice as fast.
I hope this description isn't too confusing but here is my code anyway:
using System;
using System.Net;
using SnmpSharpNet;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public static bool stop = false;
static bool min = true, eye = false, firstTick = false;
static string ipAdd = "", fileSaveLocation = "";
static System.Windows.Forms.Timer timer = new System.Windows.Forms.Timer();
static System.Windows.Forms.Timer appTimer = new System.Windows.Forms.Timer();
static int alarmCounter = 1, hours = 0, minutes = 0, seconds = 0, tenthseconds = 0, count = 0;
static bool inSNMP = false;
static TextBox textbox, timeTextbox;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
textbox = outputBox;
timeTextbox = timeBox;
ipAdd = "192.168.98.107";
fileSaveLocation = "c:/Users/bshellnut/Desktop/Eye.txt";
min = true;
inSNMP = false;
}
private void IPtext_TextChanged(object sender, EventArgs e)
{
ipAdd = IPtext.Text;
}
private void stopButton_Click(object sender, EventArgs e)
{
stop = true;
timer.Stop();
appTimer.Stop();
count = 0;
hours = minutes = seconds = tenthseconds = 0;
inSNMP = false;
}
// This is the method to run when the timer is raised.
private static void TimerEventProcessor(Object myObject,
EventArgs myEventArgs)
{
inSNMP = true;
timer.Stop();
if (firstTick == true)
{
// Sets the timer interval to 60 seconds or 1 second.
if (min == true)
{
timer.Interval = 1000 * 60;
}
else
{
timer.Interval = 1000 * 30;
}
}
// Displays a message box asking whether to continue running the timer.
if (stop == false)
{
textbox.Clear();
// Restarts the timer and increments the counter.
alarmCounter += 1;
timer.Enabled = true;
System.IO.StreamWriter file;
//if (eye == true)
//{
file = new System.IO.StreamWriter(fileSaveLocation, true);
/*}
else
{
file = new System.IO.StreamWriter(fileSaveLocation, true);
}*/
// SNMP community name
OctetString community = new OctetString("public");
// Define agent parameters class
AgentParameters param = new AgentParameters(community);
// Set SNMP version to 2 (GET-BULK only works with SNMP ver 2 and 3)
param.Version = SnmpVersion.Ver2;
// Construct the agent address object
// IpAddress class is easy to use here because
// it will try to resolve constructor parameter if it doesn't
// parse to an IP address
IpAddress agent = new IpAddress(ipAdd);
// Construct target
UdpTarget target = new UdpTarget((IPAddress)agent, 161, 2000, 1);
// Define Oid that is the root of the MIB
// tree you wish to retrieve
Oid rootOid;
if (eye == true)
{
rootOid = new Oid("1.3.6.1.4.1.128.5.2.10.14"); // ifDescr
}
else
{
rootOid = new Oid("1.3.6.1.4.1.128.5.2.10.15");
}
// This Oid represents last Oid returned by
// the SNMP agent
Oid lastOid = (Oid)rootOid.Clone();
// Pdu class used for all requests
Pdu pdu = new Pdu(PduType.GetBulk);
// In this example, set NonRepeaters value to 0
pdu.NonRepeaters = 0;
// MaxRepetitions tells the agent how many Oid/Value pairs to return
// in the response.
pdu.MaxRepetitions = 5;
// Loop through results
while (lastOid != null)
{
// When Pdu class is first constructed, RequestId is set to 0
// and during encoding id will be set to the random value
// for subsequent requests, id will be set to a value that
// needs to be incremented to have unique request ids for each
// packet
if (pdu.RequestId != 0)
{
pdu.RequestId += 1;
}
// Clear Oids from the Pdu class.
pdu.VbList.Clear();
// Initialize request PDU with the last retrieved Oid
pdu.VbList.Add(lastOid);
// Make SNMP request
SnmpV2Packet result;
try
{
result = (SnmpV2Packet)target.Request(pdu, param);
}
catch (SnmpSharpNet.SnmpException)
{
timer.Stop();
textbox.Text = "Could not connect to the IP Provided.";
break;
}
// You should catch exceptions in the Request if using in real application.
// If result is null then agent didn't reply or we couldn't parse the reply.
if (result != null)
{
// ErrorStatus other then 0 is an error returned by
// the Agent - see SnmpConstants for error definitions
if (result.Pdu.ErrorStatus != 0)
{
// agent reported an error with the request
textbox.Text = "Error in SNMP reply. " + "Error " + result.Pdu.ErrorStatus + " index " + result.Pdu.ErrorIndex;
lastOid = null;
break;
}
else
{
// Walk through returned variable bindings
foreach (Vb v in result.Pdu.VbList)
{
// Check that retrieved Oid is "child" of the root OID
if (rootOid.IsRootOf(v.Oid))
{
count++;
textbox.Text += "#" + count + " " + v.Oid.ToString() + " " + SnmpConstants.GetTypeName(v.Value.Type) +
" " + v.Value.ToString() + Environment.NewLine;
file.WriteLine("#" + count + ", " + v.Oid.ToString() + ", " + SnmpConstants.GetTypeName(v.Value.Type) +
", " + v.Value.ToString(), true);
if (v.Value.Type == SnmpConstants.SMI_ENDOFMIBVIEW)
lastOid = null;
else
lastOid = v.Oid;
}
else
{
// we have reached the end of the requested
// MIB tree. Set lastOid to null and exit loop
lastOid = null;
}
}
}
}
else
{
//Console.WriteLine("No response received from SNMP agent.");
textbox.Text = "No response received from SNMP agent.";
//outputBox.Text = "No response received from SNMP agent.";
}
}
target.Close();
file.Close();
}
else
{
// Stops the timer.
//exitFlag = true;
count = 0;
}
}
private static void ApplicationTimerEventProcessor(Object myObject,
EventArgs myEventArgs)
{
tenthseconds += 1;
if (tenthseconds == 10)
{
seconds += 1;
tenthseconds = 0;
}
if (inSNMP && !firstTick)
{
if (min)
{
seconds = 60;
}
else
{
textbox.Text += "IN 30 SECONDS!!!";
if (seconds < 30)
{
seconds = 30;
}
else
{
seconds = 60;
}
}
}
if(seconds == 60)
{
seconds = 0;
minutes += 1;
}
if(minutes == 60)
{
minutes = 0;
hours += 1;
}
timeTextbox.Text = (hours < 10 ? "00" + hours.ToString() : hours.ToString()) + ":" +
(minutes < 10 ? "0" + minutes.ToString() : minutes.ToString()) + ":" +
(seconds < 10 ? "0" + seconds.ToString() : seconds.ToString()) + "." +
(tenthseconds < 10 ? "0" + tenthseconds.ToString() : tenthseconds.ToString());
inSNMP = false;
firstTick = false;
}
private void eyeButton_Click(object sender, EventArgs e)
{
outputBox.Text = "Connecting...";
eye = true;
stop = false;
count = 0;
hours = minutes = seconds = tenthseconds = 0;
timer.Tick += new EventHandler(TimerEventProcessor);
timer.Interval = 3000;
firstTick = true;
appTimer.Tick += new EventHandler(ApplicationTimerEventProcessor);
appTimer.Interval = 100;
appTimer.Start();
timer.Start();
}
private void jitterButton_Click(object sender, EventArgs e)
{
outputBox.Text = "Connecting...";
eye = false;
stop = false;
count = 0;
hours = minutes = seconds = tenthseconds = 0;
timer.Tick += new EventHandler(TimerEventProcessor);
timer.Interval = 3000;
firstTick = true;
appTimer.Tick += new EventHandler(ApplicationTimerEventProcessor);
appTimer.Interval = 100;
appTimer.Start();
timer.Start();
}
private void Seconds_CheckedChanged(object sender, EventArgs e)
{
min = false;
}
private void Minutes_CheckedChanged(object sender, EventArgs e)
{
min = true;
}
private void exitButton_Click(object sender, EventArgs e)
{
Application.Exit();
}
private void savetextBox_TextChanged(object sender, EventArgs e)
{
fileSaveLocation = savetextBox.Text;
}
}
}

This is very easy to do with a single timer. The timer has a 1/10th second resolution (or so) and can be used directly to update the elapsed time. You can then use relative elapsed time within that timer to fire off your SNMP transaction, and you can reschedule the next one dynamically.
Here's a simple example
using System;
using System.Drawing;
using System.Windows.Forms;
class Form1 : Form
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
DateTime lastSnmpTime;
TimeSpan snmpTime = TimeSpan.FromSeconds(30);
DateTime startTime;
TextBox elapsedTimeTextBox;
Timer timer;
public Form1()
{
timer = new Timer { Enabled = false, Interval = 10 };
timer.Tick += new EventHandler(timer_Tick);
elapsedTimeTextBox = new TextBox { Location = new Point(10, 10), ReadOnly = true };
Controls.Add(elapsedTimeTextBox);
}
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
startTime = DateTime.Now;
timer.Start();
}
void timer_Tick(object sender, EventArgs e)
{
// Update elapsed time
elapsedTimeTextBox.Text = (DateTime.Now - startTime).ToString("g");
// Send SNMP
if (DateTime.Now - lastSnmpTime >= snmpTime)
{
lastSnmpTime = DateTime.Now;
// Do SNMP
// Adjust snmpTime as needed
}
}
}
Updated Q&A
With this code the timer fires once at the beginning where after I
press the stop button and call timer.Stop() and then press my start
button the timer doesn't fire until roughly 12 seconds later. Will
resetting the DateTimes fix this?
When the user presses the Start button, set lastSnmpTime = DateTime.MinValue. This causes the TimeSpan of (DateTime.Now - lastSnmpTime) to be over 2,000 years, so it will be greater than snmpTime and will fire immediately.
Also my output time in the text box looks like this: 0:00:02.620262.
Why is that? Is there a way to make it display only 0:00:02.62?
When you subtract two DateTime values, the result is a TimeSpan value. I used a standard TimeSpan formatting string of "g". You can use a custom TimeSpan formatting string of #"d\:hh\:mm\:ss\.ff" to get days:hours:minutes:seconds.fraction (2 decimal places).
Also will the timer go on and print out to the text box when it is run
for over 9 hours? Because I plan to have this running for 24 hrs+
If you use the custom format with 'd' to show the number of days, it will run for TimeSpan.MaxValue which is slightly more than 10,675,199 days, which is more than 29,000 years.