Parsing times above 24 hours in C#

Question

Suppose a time stamp (just time or date and time) where the time can roll over to the next day:

00:00:00 <- midnight

01:00:00 <- 1 AM

23:00:00 <- 11 PM

24:00:00 <- midnight, day + 1

25:00:00 <- 1 AM, day + 1

What would be a way to parse it easily into a C# DateTime that would perform the carry-over to the next day? In other words, "01:00:00" would become "0001-01-01 01:00:00" and "25:00:00" would become "0001-01-02 01:00:00".

EDIT:

I should mention that this fails miserably (i.e FormatException):

DateTime.ParseExact("0001-01-01 25:00:00", "yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture);

Baileybailie

For those who would be curious about this notation, it's used sometimes by transit authorities to denote day of operation going after midnight. – Baileybailie

What is the actual string you have to parse? It is not 0001-01-01 25:00:00 I'm sure. – Steatite

@HansPassant: No, it's really "25:00:00". I just put in the date in my sample code to not make it default to the current date. Sorry if that's confusing. – Baileybailie

Just parse it with a Regex and three int.Parse(). – Steatite

@HansPassant: Yeah, looks like I'm going to go that way. I was just wondering if there was something out-of-the-box in DateTime that allowed this. – Baileybailie

Answer 1

Since you're trying to represent a period of time from an arbitrary point, rather than as a specific date, perhaps you would be better off using the System.TimeSpan class? This allows you to set values of more than 24 hours in the constructor, and can be used with DateTime objects like this:

System.TimeSpan timestamp = new System.TimeSpan(25, 0, 0);
System.DateTime parsedDateTime = new DateTime(0, 0, 0);
parsedDateTime = parsedDateTime.Add(timestamp);
Console.WriteLine(parsedDateTime.ToString("yyyy-MM-dd HH:mm:ss"));  //Output as "0001-01-02 01:00:00"

NOTE: Code is untested.

EDIT: In terms of parsing the strings, I can't think of any basic .NET objects that parse strings with values greater than 23 for the hour (since 25 is an invalid hour of the day), but assuming that the format is consistent, you could create a very simple string parsing routine (or even a regular expression) to read the values individually, and load the constructor manually.

Atwood

You make a good point, it really is time from an arbitrary point (say midnight, but any day), so TimeSpan is indeed appropriate. – Baileybailie

Answer 2

If you have an existing DateTime value you can add to, you can always use a TimeSpan:

string dt = "25:00:00";
int hours = int.Parse(dt.Split(':')[0]);
TimeSpan ts = TimeSpan.FromHours(hours);

TimeSpan.Parse() doesn't work directly in this case because it complains (fair enough!) about the 25 in the hour notation.

Asoka

Answer 3

If you want to code it out... this should be a starting point:

 string dateString = "0001-01-01 25:00:00";
 string[] parts = dateString.Split(' '); //now have '0001-01-01' and '25:00:00'

 string datePart = parts[0]; // '0001-01-01'
 string[] timeParts = parts[1].Split(':'); //now have '25', '00', and '00

 DateTime initialDate = DateTime.ParseExact(datePart, "yyyy-MM-dd", CultureInfo.InvariantCulture);//use the date as a starting point

 //use the add methods to get your desired datetime
 int hours = int.Parse(timeParts[0]);
 int minutes = int.Parse(timeParts[1]);
 int seconds = int.Parse(timeParts[2]);

 DateTime resultDate = initialDate.AddHours(hours)
                                    .AddMinutes(minutes)
                                    .AddSeconds(seconds);

Of course, it makes assumptions that the input is formatted properly and is parsable, etc.. In addition, you could definitely use timespan instead of the individual add methods for hour, minute, second as some other answers are..

Trauner

Answer 4

You are specifying an invalid date. So not only can you not parse it, you cannot store it!

How about a nice TimeSpan object instead? (It also has a Parse() method.)

Alternatively, use a sscanf()-type function like the one at http://www.blackbeltcoder.com/Articles/strings/a-sscanf-replacement-for-net to extract each number separate. (Best if you have no control over the string format being read.)

Maurili

The TimeSpan.Parse method throws an OverflowException on parsing "25:00:00". – Baileybailie

@MPelletier: Please see the link I added to my answer. If the format is non-standard and you can't change that, you'll need to extract the values separately. – Maurili

it may be invalid in your mind but not neccessarily invalid per se There are indeed older time tracking systems that use a so called 24+ format. This is especially needed to store night shifts when you work start and work end are just stored as hours and minutes – Tisman

Answer 5

In case nobody points out an out-of-the-box answer, here is a neat ActionScript class I wrote to parse time inputs (human input)...

https://github.com/appcove/AppStruct/blob/master/Flex/AppStruct/src/AppStruct/TimeInput.as

It would be very simple to port this to C#, and you could tweak the 24 hour logic to result in #days, #hours, #minutes.

Good luck!

Enterogastrone

Answer 6

https://en.wikipedia.org/wiki/Date_and_time_notation_in_Japan#Time https://ja.wikipedia.org/wiki/30%E6%99%82%E9%96%93%E5%88%B6

[GeneratedRegex(
    "^(?<year>[0-9]{4})-(?<month>[0-9]{2})-(?<day>[0-9]{2}) (?<hour>[0-9]{2}):(?<minute>[0-9]{2}):(?<second>[0-9]{2})$",
    RegexOptions.Compiled, matchTimeoutMilliseconds: 100)]
private static partial Regex ParseHoursBeyond24Regex();

public static DateTime ParseHoursBeyond24(string dateTime)
{
    var match = ParseHoursBeyond24Regex().Match(dateTime);
    return match.Success
        ? new DateTime(
            int.Parse(match.Groups["year"].ValueSpan),
            int.Parse(match.Groups["month"].ValueSpan),
            int.Parse(match.Groups["day"].ValueSpan),
            hour: 0,
            int.Parse(match.Groups["minute"].ValueSpan),
            int.Parse(match.Groups["second"].ValueSpan))
            .AddHours(int.Parse(match.Groups["hour"].ValueSpan))
        : default;
}

Phthalocyanine