Handle negative time spans

Question

In my output of a grid, I calculate a TimeSpan and take its TotalHours. e.g.

(Eval("WorkedHours") - Eval("BadgedHours")).TotalHours

The goal is to show the TotalHours as 39:44, so I need to convert the value from 7.5 to 07:30. This is no problem... unless it's negative!

I can create a TimeSpan object from Hours with

TimeSpan.FromHours( (Eval("WorkedHours") - Eval("BadgedHours")).TotalHours)

If it's negative, I can't convert it to a DateTime to use the .ToString("HH:mm") method, and the TimeSpan object does not support the format string.

Zugzwang

Please consider reformatting the code snippets as inline code or code sections, and add the appropriate platform tag (I'd guess .NET from your snippets). – Oneiric

Note that a difference between 2 TimeOnly values is different -it is always positive and can be confusing #73040186 – Hip

Answer 1

Isn't there a TimeSpan.Duration method? I think this would handle what you are trying to do.

Returns a new TimeSpan object whose value is the absolute value of the current TimeSpan object.

Percussion

This is the easiest way, just subtract your two DateTimes, call Duration() on the result, and then do TotalHours. – Henotheism

Answer 2

static string ToHMString(TimeSpan timespan) { 
    if (timespan.Ticks < 0) return "-" + ToHMString(timespan.Negate());

    return timespan.TotalHours.ToString("#0") + ":" + timespan.Minutes.ToString("00");
}

Console.WriteLine(ToHMString(TimeSpan.FromHours(3)));       //Prints "3:00"
Console.WriteLine(ToHMString(TimeSpan.FromHours(-27.75)));  //Prints "-28:45"

This will also work correctly if the timespan is longer than 24 hours.

Utu

Answer 3

Just multiply it by -1 or use an absolute value function.

Tramway

For anyone who googled it: use TimeSpan.Duration method. From MSDN: "Returns a new TimeSpan object whose value is the absolute value of the current TimeSpan object". – Wellknown

Answer 4

There is a Negate method in the TimeSpan class.

Link to the MSDN documentation: TimeSpan.Negate Method()

Marozik

Answer 5

The simple solution would be to do:

string format = "HH:mm";
if(hours < 0)
  format = "-" + format;

hours = Math.Abs(hours)

Sigler

Answer 6

its working .try this

mytimespam.Negate();

Mccreery

time spam, hehe ;) – Flurried

Answer 7

Hi i worked this into a bit of code i have been writing, hope it helps

(results) is an int variable

(TimeSpan.FromMinutes(result)) < TimeSpan.Zero ? "-" + TimeSpan.FromMinutes(result).ToString(@"hh\:mm") : "" + TimeSpan.FromMinutes(result).ToString(@"hh\:mm");

Troup

Answer 8

I checked to every where.But i didnt get a correct answer that why i used this way to finish

TimeSpan diff = actualout.Subtract(actualin);
 string a =(diff.ToString()).ToString();
if(a.Contains("-"))
 {        
 diff = new TimeSpan(0,0,0,0);
}

Spam

Much more simple way is to just compare if (diff < TimeSpan.Zero) – Pforzheim

Answer 9

TimeSpan Diff = Date1 - Date2;

if ((int)Diff.TotalDays < 0) { // your code }

Karylkarylin