System.DateTime.Now is giving bad results - c#

The main logic of a utility tool is in a function like this:
private void Run()
{
DateTime startTime = DateTime.Now;
Prepare();
Search();
Process();
DateTime endTime = DateTime.Now;
TimeSpan duration = endTime.Subtract(startTime);
Console.WriteLine("Run took {0:00}:{1:00}:{2:00}",
(int)duration.TotalHours, duration.Minutes, duration.Seconds);
}
When I run this I can see with my own eyes it is taking at least 5 seconds (Process() method spews console output which I can observe happening for 5-6s). But it reports "Run took 00:00:01".
I don't expect time to have microsecond precision but why is it so totally inaccurate here?
Update:
Following advice I also ran a StopWatch over the same period and compared against subtracting two DateTime, and also debugged the code. The two methods agree to a fraction of a second... StopWatch in the debugger had 1139 milliseconds. My hypothesis is that somehow time writing to the console is not included but I have no way to back that up (or disprove it).

I doubt that the problem is with DateTime. Likely, the program finished and sent the output to the console buffer, which is taking its sweet time actually displaying it. What you're seeing is output lag.

To become confident in what you see is what really happens, write for test sake:
DateTime startTime = DateTime.Now;
Thread.Sleep(5000);
DateTime endTime = DateTime.Now;
TimeSpan duration = endTime.Subtract(startTime);
Console.WriteLine("Run took {0:00}:{1:00}:{2:00}",
(int)duration.TotalHours, duration.Minutes, duration.Seconds);
Also, it's better to use Stopwatch class for your purposes

Why not use Stopwatch?
Stopwatch ss = new Stopwatch();
ss.Start();
// Some quantity of work.....
ss.Stop();
Console.WriteLine("Elapsed time: {0}", ss.Elapsed.TotalMilliseconds);

DateTime isn't very accurate for this kind of measurement. You should use the stopwatch class.
http://msdn.microsoft.com/en-us/library/system.diagnostics.stopwatch.aspx

DateTime startTime = DateTime.Now;
Thread.Sleep(5000);
DateTime endTime = DateTime.Now;
TimeSpan duration = endTime.Subtract(startTime);
Console.WriteLine(duration.Seconds);
Prints "5". Are you sure your test case is what it is?

Related

Looping 24 hour clock time difference

I created a time calculator so someone can enter a start time in a textbox and an end time in another textbox in 24 hour time format and it will calculate the difference and show it in a label.
How can I make my code do the same thing but with a loop? I'm just looking to make the code shorter instead of having a block of code for each day of the week, shown below is just the Monday and Tuesday code.
//Monday
TimeSpan Mon1In, Mon1Out;
if (!TimeSpan.TryParse(TextBoxInMon1.Text, out Mon1In))
Mon1In = default(TimeSpan);
if (!TimeSpan.TryParse(TextBoxOutMon1.Text, out Mon1Out))
Mon1Out = default(TimeSpan);
MonLabel1.Text = (Mon1Out - Mon1In).TotalHours.ToString("f2");
//Tuesday
TimeSpan Tues1In, Tues1Out;
if (!TimeSpan.TryParse(TextBoxInTues1.Text, out Tues1In))
Tues1In = default(TimeSpan);
if (!TimeSpan.TryParse(TextBoxOutTues1.Text, out Tues1Out))
Tues1Out = default(TimeSpan);
TuesLabel1.Text = (Tues1Out - Tues1In).TotalHours.ToString("f2");
You can just make a function. This is called refactoring.
private void GetTimeValues(TextBox txtIn, TextBox txtOut,
out TimeSpan inTime, out Timespan outTime)
{
if (!TimeSpan.TryParse(txtIn.Text, out inTime))
inTime = default(TimeSpan);
if (!TimeSpan.TryParse(txtOut.Text, out outTime))
outTime = default(TimeSpan);
}
Then call the function and set your label.
TimeSpan Mon1In, Mon1Out;
GetTimeValues(TextBoxInMon1, TextBoxOutMon1, out Mon1In, out Mon1Out);
MonLabel1.Text = (Mon1Out - Mon1In).TotalHours.ToString("f2");
You should probably use a more descriptive function name, this was just the first thing I thought of.
You could also include the label logic inside the function as well, just thread the information along in the same fashion.

Difference between two datetimes

I have a datetime, I want to show the difference from DateTime.Now to received datetime and bind it. The result should be something like this:
1d 15h 13m 7s
What is the best way to do it? StringFormat? IValueConverter?
I'd suggest using the Timespans ToString method and custom TimeSpan format strings
Timespans if you aren't already aware are designed for measuring time intervals like this and can be convenienty obtained by subtracting one date from another.
var startDate = new DateTime(2013,1,21);
var currentDate = DateTime.Now;
TimeSpan interval = currentDate - startDate;
string intervalInWords = String.Format("{0:%d} days {0:%h} hours {0:%m} minutes {0:%s} seconds", interval);
Console.WriteLine(intervalInWords);
This will print out something like
267 days 10 hours 45 minutes 21 seconds
As has been noted in comments because these datetimes may be in different timezones/daylight saving times you should be very careful using this technique. Using UTCtime for both which is consistent throughout the whole year should be sufficient if that is feasible. In general it is often best policy to save all datetimes as UTC along with the timezone/offset (if required) and then if they are needed in a specific timezone offset convert on display.
Use TimeSpan
Example:
DateTime oldDate = new DateTime(2002,7,15);
DateTime newDate = DateTime.Now;
// Difference in days, hours, and minutes.
TimeSpan ts = newDate - oldDate;
// Difference in days.
int differenceInDays = ts.Days;
Now you can change it according to your requirement.
The other answers are correct from the formatting point of view, but just to address the WPF angle, I'm guessing you want to update a label/textbox so it constantly contains an accurate duration?
If so, you can do this with the timer and the dispatcher.
Timer code:
//duration in milliseconds, 1000 is 1 second
var timer = new Timer(1000);
timer.Elapsed += timer_Elapsed;
timer.Start();
Timer elapsed code:
//this is set elsewhere
private readonly DateTime _received;
void timer_Elapsed(object sender, ElapsedEventArgs e)
{
Application.Current.Dispatcher.Invoke(
DispatcherPriority.Normal,
new Action(()
=> //replace label1 with the name of the control you wish to update
label1.Content =
string.Format("{0:%d} days {0:%h} hours {0:%m} minutes {0:%s} seconds"
, (DateTime.Now - _received))));
}
You can use TimeSpan, also look out [here][1]
[1]: Showing Difference between two datetime values in hours i would suggest you to go through TimeSpan.
DateTime startDate = Convert.ToDateTime(2008,8,2);
DateTime endDate = Convert.ToDateTime(2008,8,3);
TimeSpan duration = startDate - endDate;
Create a property like DateProp of type DateTime to which you'll bind on your XAML , and assuming your property is Other_date_here, initialize it like this:
DateProp = DateTime.Now.Subtract(Other_date_here);
Last, on your XAML, bind it and set the formatting like this:
Text="{Binding Date, StringFormat=d day H hours m minutes s seconds}"
(or whatever other format you like:).

Display duration in milliseconds

I want to display duration with milliseconds on a web page. So far I have done this:
I managed to display this output on a label: 00:02:50, but I want to display milliseconds as well, so the result should look like this 00:02:50:000. How do I achieve this?
Code behind:
protected void Page_Load(object sender, EventArgs e)
{
DateTime startTime = DateTime.Now;
// sleep for 2.5s
Thread.Sleep(2500);
DateTime stopTime = DateTime.Now;
TimeSpan duration = stopTime - startTime;
Result.Text = duration.ToString("mm':'ss':'ff");
}
First of all, if you're timing things I would recommend using the StopWatch class as that's what it's there for. You can find it in the System.Diagnostics namespace: System.Diagnostics.Stopwatch.
You can instantiate a new one and start measuring the elapsed amount of time with one line of code: var stop = System.Diagnostics.Stopwatch.StartNew(); and then stop the timer with the stop method: stop.Stop();. You can then return the elapsed time using the Elapsed property var elapsed = stop.Elapsed;.
Then in order to display the elapsed time with milliseconds you would call the ToString method on the elapsed timespan with the correct parameters.
So putting it all together your code would look like this:
protected void Page_Load(object sender, EventArgs e)
{
var timer = System.Diagnostics.Stopwatch.StartNew();
// sleep for 2.5s
Thread.Sleep(2500);
timer.Stop();
var elapsed = timer.Elapsed;
Result.Text = elapsed.ToString("mm':'ss':'fff");
}
Hope that helps!
James
Your current code should be displaying minutes, seconds, and hundredths of a second.
Result.Text = duration.ToString("mm':'ss':'ff");
To display milliseonds instead of hundredths of a second:
// output: 00:02:500
Result.Text = duration.ToString("mm':'ss':'fff");
See the documentation for Custom Date and Time Format Strings.
The doc says: "fff" gives you:
The milliseconds in a date and time value.
You're using "ff" which gives you:
The hundredths of a second in a date and time value.
So, change your code to:
duration.ToString("mm':'ss':'fff");
I think you're confused. In your case 00:02:50 means 2 seconds and 50 hundredths of second. If you want to display milliseconds, use format like mm':'ss':'fff (notice the one added f). This will print something like 00:02:500, i.e. 2 seconds and 500 thousandths of second, or 2 s 500 ms.
But this doesn't mean your measurements will be precise down to millisecond. That's not what DateTime.Now is meant to do. If you want to make measurements this precise, you should use StopWatch.
Use TimeSpan.ToString Method with custom format.
The returned string is formatted with the "c" format specifier and has the following format:
[-][d.]hh:mm:ss[.fffffff]
Elements in square brackets ([ and ]) may not be included in the returned string. Colons and periods (: and.) are literal characters.
Result.Text = duration.ToString("mm:ss:fff");
or
Result.Text = duration.ToString("hh:mm:ss.fff");
Ref :Custom Date and Time Format Strings, The "fff" Custom Format Specifier
DateTime date1 = new DateTime(2008, 8, 29, 19, 27, 15, 18);
CultureInfo ci = CultureInfo.InvariantCulture;
Console.WriteLine(date1.ToString("hh:mm:ss.fff", ci));
// Displays 07:27:15.018
Otherwise just use the properties from the timespan like this:
var result = String.Format("{0}:{1}:{2}", duration.Minutes, duration.Seconds, duration.Milliseconds);
Result.Text = result
This way I think you gain more control over what you want to display, instead of formatting the timespan in the ToString()-method which more easily allows typos to be made...
Hope this helps!
Update:
To add the hours as well this is how it'll look like:
var result = String.Format("{0}:{1}:{2}:{3}", duration.Hours, duration.Minutes, duration.Seconds, duration.Milliseconds);

How to set current time to a value

I was just wondering if there is a way to get the current time and set it into a value.
If its 12:06 AM.. I want to get that time and set it into currentTime.
Example
float currentTime = 0;
currentTime = 12.06;
As others have mentioned, the DateTime class would be ideal for this, and to work out the difference between 2 date/times:
DateTime end = DateTime.Now;
DateTime start = new DateTime(2011, 12, 5, 12, 6,0);
double hours = (end - start).TotalHours;
The subtraction of DateTime objects results in a TimeSpan object that you can use to see the hours/minutes etc.
try DateTime class
DateTime dt = DateTime.Now;
Is this what you're looking for?
DateTime currentTime;
currentTime = DateTime.Now;
Don't use floats or strings. You can do all kinds of cool things using DateTime.
Here's how you'd get the hours that someone worked:
var clockIn = new DateTime(2011,12,4,9,0,0); // December 4th, 9 AM
var clockOut = new DateTime(2011,12,4,17,0,0); // December 4th, 5 PM
var duration = clockOut - clockIn; // TimeSpan
Console.Write(duration.TotalHours); // 8
A few people have mentioned how, but as a 'better' recommendation you should use
DateTime currentTime = DateTime.UtcNow
Otherwise you have issues when the clocks go back, if your timing code is run on those days. (plus it is far easier to alter the UTC time to local time than it is to convert a '1am' to UTC (as there will be two of them when the clocks go back)
Well if you really what it as a float then try:
var currentDate = DateTime.Now;
float currentTime = float.Parse((currentDate.Hour > 12 ? currentDate.Hour -12 :
currentDate.Hour) + "." + currentDate.Minute);
I wouldn't recommend comparing dates or time with floats. A better options would be to use timespans.
You should be using a Timespan instance for time related values, you can use the flexibility to get the required values like
TimeSpan ts = DateTime.Now.TimeOfDay;
ts.ToString("hh:mm") // this could be what you are looking for
You could then use ts.TotalHours which would give you fractional hours (as a double) else you could construct a string specifically using ts.Hours ..ts.Minutes play around and it could be prove useful.
Try the following:
DateTime StartTime=StartTime value;
DateTime CurrentTime=DateTime.Now;
TimeSpan dt = CurrentTime.Subtract(StartTime);
In dt you will get a working time period.
If you want to have the difference between two times, then do this:
DateTime dateOne = DateTime.Parse(enteredTime);
DateTime dateTwo = DateTime.Now;
TimeSpan difference = dateOne - dateTwo;

Differences between 2 times?

StartCopying = DateTime.Now;
File.Copy(#"C:\Users\sshap5x\Desktop\line4\shiraDebbi\Hackers.avi", #"C:\Users\sshap5x\Desktop\test\Hackers.avi", true);
EndCopying = DateTime.Now;
CopyingTime1 = (endCopying - startCopying).Duration;
What is the problem with my code?
Copying time is TimeSpan object.
The assignments are to StartCopying and EndCopying but your read the data from other variables startCopying and endCopying.
C# is case sensitive.
And also Duration is a method. so you need to use .Duration()
And as suggested in the comments to your question, for better resolution use the Stopwatch class.
// This prints 0.1 (roughly)
DateTime start = DateTime.Now;
Thread.Sleep(100);
var diff = DateTime.Now - start;
Console.WriteLine(diff.TotalSeconds);
In your code (which wouldn't even compile) you use .Duration as a property when it is in fact a method. In any case, you don't need to call Duration at all because the result returned by the subtraction is a TimeSpan containing the difference. You can then get this diff in whatever format you need (milliseconds, seconds, hours, days, etc.).
The only need for the Duration method is if you are unsure whether the result is negative or positive.
Did you forget the () for Duration and capitalisation for the variables EndCopying and StartCopying?
DateTime StartCopying = DateTime.Now;
DateTime EndCopying = DateTime.Now;
TimeSpan CopyingTime1 = (EndCopying - StartCopying).Duration();

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