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);
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.
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.
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..
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!
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.)
Related
Using C#, I am trying to populate a variable with a known filename + date. The catch is that the date must always be the last day of the previous month. It must also have no slashes or hyphens, and the year must be two digits. For example, if it is now November 27 2015, I need my filename to be: Foobar_103115.txt
As a programmer who still has much to learn, I have written the clunky code below and it does achieve my desired result, even though it will obviously break after the end of this century. My code is written this way because I could not figure out a more direct syntax for getting the date I want, complete with the specified formatting.
My question is this: What would be a more elegant and efficient way of recreating the below code?
I have commented all the code for any novice programmers who might be interested in this. I know the experts I'm asking for help from don't need it.
public void Main()
{
String Filename
DateTime date = DateTime.Today;
var FirstDayOfThisMonth = DateTime.Today.AddDays(-(DateTime.Today.Day - 1)); //Gets the FIRST DAY of each month
var LastDayOfLastMonth = FirstDayOfThisMonth.AddDays(-1); //Subtracts one day from the first day of each month to give you the last day of the previous month
String outputDate = LastDayOfLastMonth.ToShortDateString(); //Reformats a long date string to a shorter one like 01/01/2015
var NewDate = outputDate.Replace("20", ""); //Gives me a two-digit year which will work until the end of the century
var NewDate2 = NewDate.Replace("/", ""); //Replaces the slashes with nothing so the format looks this way: 103115 (instead of 10/31/15)
Filename = "Foobar_" + NewDate2 + ".txt"; //concatenates my newly formatted date to the filename and assigns to the variable
Sounds like you want something more like:
// Warning: you should think about time zones...
DateTime today = DateTime.Today;
DateTime startOfMonth = new DateTime(today.Year, today.Month, 1);
DateTime endOfPreviousMonth = startOfMonth.AddDays(-1);
string filename = string.Format(CultureInfo.InvariantCulture,
"FooBar_{0:MMddyy}.txt", endOfPreviousMonth);
I definitely wouldn't use ToShortDateString here - you want a very specific format, so express it specifically. The results of ToShortDateString will vary based on the current thread's culture.
Also note how my code only evaluates DateTime.Today once - this is a good habit to get into, as otherwise if the clock "ticks" into the next day between two evaluations of DateTime.Today, your original code could give some pretty odd results.
I want to convert a Timespan to Datetime. How can I do this?
I found one method on Google:
DateTime dt;
TimeSpan ts="XXX";
//We can covnert 'ts' to 'dt' like this:
dt= Convert.ToDateTime(ts.ToString());
Is there any other way to do this?
It is not very logical to convert TimeSpan to DateTime. Try to understand what leppie said above. TimeSpan is a duration say 6 Days 5 Hours 40 minutes. It is not a Date. If I say 6 Days; Can you deduce a Date from it? The answer is NO unless you have a REFERENCE Date.
So if you want to convert TimeSpan to DateTime you need a reference date. 6 Days & 5 Hours from when? So you can write something like this:
DateTime dt = new DateTime(2012, 01, 01);
TimeSpan ts = new TimeSpan(1, 0, 0, 0, 0);
dt = dt + ts;
While the selected answer is strictly correct, I believe I understand what the OP is trying to get at here as I had a similar issue.
I had a TimeSpan which I wished to display in a grid control (as just hh:mm) but the grid didn't appear to understand TimeSpan, only DateTime . The OP has a similar scenario where only the TimeSpan is the relevant part but didn't consider the necessity of adding the DateTime reference point.
So, as indicated above, I simply added DateTime.MinValue (though any date will do) which is subsequently ignored by the grid when it renders the timespan as a time portion of the resulting date.
TimeSpan can be added to a fresh DateTime to achieve this.
TimeSpan ts="XXX";
DateTime dt = new DateTime() + ts;
But as mentioned before, it is not strictly logical without a valid start date. I have encountered
a use-case where i required only the time aspect. will work fine as long as the logic is correct.
You need a reference date for this to be useful.
An example from
http://msdn.microsoft.com/en-us/library/system.datetime.add.aspx
// Calculate what day of the week is 36 days from this instant.
System.DateTime today = System.DateTime.Now;
System.TimeSpan duration = new System.TimeSpan(36, 0, 0, 0);
System.DateTime answer = today.Add(duration);
System.Console.WriteLine("{0:dddd}", answer);
Worked for me.
var StartTime = new DateTime(item.StartTime.Ticks);
If you only need to show time value in a datagrid or label similar, best way is convert directly time in datetime datatype.
SELECT CONVERT(datetime,myTimeField) as myTimeField FROM Table1
You could also use DateTime.FromFileTime(finishTime) where finishTme is a long containing the ticks of a time. Or FromFileTimeUtc.
An easy method, use ticks:
new DateTime((DateTime.Now - DateTime.Now.AddHours(-1.55)).Ticks).ToString("HH:mm:ss:fff")
This function will give you a date (Without Day / Month / Year)
A problem with all of the above is that the conversion returns the incorrect number of days as specified in the TimeSpan.
Using the above, the below returns 3 and not 2.
Ideas on how to preserve the 2 days in the TimeSpan arguments and return them as the DateTime day?
public void should_return_totaldays()
{
_ts = new TimeSpan(2, 1, 30, 10);
var format = "dd";
var returnedVal = _ts.ToString(format);
Assert.That(returnedVal, Is.EqualTo("2")); //returns 3 not 2
}
First, convert the timespan to a string, then to DateTime, then back to a string:
Convert.ToDateTime(timespan.SelectedTime.ToString()).ToShortTimeString();
I have TimeSpan data represented as 24-hour format, such as 14:00:00, I wanna convert it to 12-hour format, 2:00 PM, I googled and found something related in stackoverflow and msdn, but didn't solve this problem, can anyone help me? Thanks in advance.
Update
Seems that it's possible to convert 24-hour format TimeSpan to String, but impossible to convert the string to 12-hour format TimeSpan :(
But I still got SO MANY good answers, thanks!
(Summing up my scattered comments in a single answer.)
First you need to understand that TimeSpan represents a time interval. This time interval is internally represented as a count of ticks an not the string 14:00:00 nor the string 2:00 PM. Only when you convert the TimeSpan to a string does it make sense to talk about the two different string representations. Switching from one representation to another does not alter or convert the tick count stored in the TimeSpan.
Writing time as 2:00 PM instead of 14:00:00 is about date/time formatting and culture. This is all handled by the DateTime class.
However, even though TimeSpan represents a time interval it is quite suitable for representing the time of day (DateTime.TimeOfDay returns a TimeSpan). So it is not unreasonable to use it for that purpose.
To perform the formatting described you need to either rely on the formatting logic of DateTime or simply create your own formatting code.
Using DateTime:
var dateTime = new DateTime(timeSpan.Ticks); // Date part is 01-01-0001
var formattedTime = dateTime.ToString("h:mm tt", CultureInfo.InvariantCulture);
The format specifiers using in ToString are documented on the Custom Date and Time Format Strings page on MSDN. It is important to specify a CultureInfo that uses the desired AM/PM designator. Otherwise the tt format specifier may be replaced by the empty string.
Using custom formatting:
var hours = timeSpan.Hours;
var minutes = timeSpan.Minutes;
var amPmDesignator = "AM";
if (hours == 0)
hours = 12;
else if (hours == 12)
amPmDesignator = "PM";
else if (hours > 12) {
hours -= 12;
amPmDesignator = "PM";
}
var formattedTime =
String.Format("{0}:{1:00} {2}", hours, minutes, amPmDesignator);
Admittedly this solution is quite a bit more complex than the first method.
TimeSpan represents a time interval not a time of day. The DateTime structure is more likely what you're looking for.
You need to convert the TimeSpan to a DateTime object first, then use whatever DateTime format you need:
var t = DateTime.Now.TimeOfDay;
Console.WriteLine(new DateTime(t.Ticks).ToString("hh:mm:ss tt"));
ToShortTimeString() would also work, but it's regional-settings dependent so it would not display correctly (or correctly, depending on how you see it) on non-US systems.
TimeSpan represents a time interval (a difference between times),
not a date or a time, so it makes little sense to define it in 24 or 12h format. I assume that you actually want a DateTime.
For example 2 PM of today:
TimeSpan ts = TimeSpan.FromHours(14);
DateTime dt = DateTime.Today.Add(ts);
Then you can format that date as you want:
String formatted = String.Format("{0:d/M/yyyy hh:mm:ss}", dt); // "12.4.1012 02:00:00" - german (de-DE)
http://msdn.microsoft.com/en-us/library/az4se3k1%28v=vs.100%29.aspx
Try This Code:
int timezone = 0;
This string gives 12-hours format
string time = DateTime.Now.AddHours(-timezone).ToString("hh:mm:ss tt");
This string gives 24-hours format
string time = DateTime.Now.AddHours(-timezone).ToString("HH:mm:ss tt");
Assuming you are staying in a 24 hour range, you can achieve what you want by subtracting the negative TimeSpan from Today's DateTime (or any date for that matter), then strip the date portion:
DateTime dt = DateTime.Today;
dt.Subtract(-TimeSpan.FromHours(14)).ToShortTimeString();
Yields:
2:00 PM
String formatted = yourDateTimeValue.ToString("hh:mm:ss tt");
It is very simple,
Let's suppose we have an object ts of TimesSpan :
TimeSpan ts = new TimeSpan();
and suppose it contains some value like 14:00:00
Now first convert this into a string and then in DateTime
as following:
TimeSpan ts = new TimeSpan(); // this is object of TimeSpan and Suppose it contains
// value 14:00:00
string tIme = ts.ToString(); // here we convert ts into String and Store in Temprary
// String variable.
DateTime TheTime = new DateTime(); // Creating the object of DateTime;
TheTime = Convert.ToDateTime(tIme); // now converting our temporary string into DateTime;
Console.WriteLine(TheTime.ToString(hh:mm:ss tt));
this will show the Result as: 02:00:00 PM
Normal Datetime can be converted in either 24 or 12 hours format.
For 24 hours format - MM/dd/yyyy HH:mm:ss tt
For 12 hours format - MM/dd/yyyy hh:mm:ss tt
There is a difference of captial and small H.
dateTimeValue.ToString(format, CultureInfo.InvariantCulture);
i'm currently working on a little project and i'm stuck with a little problem.
I would like my program to call a method CheckDate on boot.
This method would read in a .txt file to see the last saved date in (yyyy/mm/dd) format.
Then it would compare it with todays date and if it's not the same go on with some instructions.I've read the doc here but can't quite find which method best suites my need.
Question 1: Is there a way to get today's date in (yyyy/mm/dd) format?
Question 2: What's the easiest way to compare Dates in C#?
Thanks in advance.
1. DateTime.Now.ToString("yyyy/MM/dd")
2. DateTime.Parse(input).Date == DateTime.Now.Date
You can get today's date as a string by simply formatting a date.
String today = String.Format("{0: yyyy/MM/dd}", DateTime.Now);
String today = DateTime.Now.ToString("yyyy/MM/dd");
I would advise against using a text file as your means of saving data but if you are going with that system the only thing you would have to do is check to see if the date from the text file matches the date you formatted. Simply comparing formatted strings should do the trick.
if (string a == string b)
You could even put it in one line without having to format stuff separately
if (DateTime.Now.ToString("yyyy/MM/dd").Equals("date pulled from txt file"))
What's the easiest way to compare Dates in C#?
Store them not as text but in a DatteTime.
Compare the variables.
If there is a time in both, compare a.Date == b.Date.
Is there a way to get today's date in (yyyy/mm/dd) format?
Yes. This is wrong, though. PARSE The wrong input and compare the parsed data.
There is a DateTime.Compare method that you could use http://msdn.microsoft.com/en-us/library/system.datetime.compare.aspx - this should also let you use the built-in < and > operators.
By the letter of the question:
1:
DateTime.Now.ToString(#"yyyy\/MM\/dd")
2:
if(d1 < d2)...
if(d2 >= d1)...
etc.
However.
DateTime dt;
if(DateTime.TryParseExact(readInString, "yyyy-MM-dd", null, DateTimeStyles.AssumeLocal, out dt))
{
if(dt != DateTime.Now.Date)
{
//Code for case where it's no longer that day goes here.
}
}
else
{
//Code for someone messed up the file and it's not a valid date any more goes here.
}
You're doing this for computer-reading, not human-reading, so use the standard format rather than the conventional format (standard as in ISO, but also every country except North Korea has it as the national standard): yyyy-MM-dd (Edit: I see you're in Canada, CSA Z234.5:1989 is the relevant national standard on date-times for technical purposes; it says to use yyyy-MM-dd).
You should do it the other way around, read the string, parse the date, and do the comparison.
you might want to have a look at the FileInfo-Class ... you can compare the LastWriteTime Member to DateTime.Today
DateTime d1 = DateTime.Now;
DateTime d2 = d1.AddMilliseconds(123456789);
string formattedDate = d1.ToString("yyyy/MM/dd");
TimeSpan ts = d2 - d1;
double dayDiff = ts.TotalDays;
double hourDiff = ts.TotalHours;
double minuteDiff = ts.TotalMinutes;
double secondDiff = ts.TotalSeconds;
double milDiff = ts.TotalMilliseconds;
Console.WriteLine("Formatted Date: {0}\r\nDate Diff:\r\nTotal Days: {1}; Total Hours: {2}; Total Minutes: {3}; Total Seconds: {4}; Total Milliseconds: {5}", formattedDate,dayDiff,hourDiff,minuteDiff,secondDiff,milDiff);
Output:
Formatted Date: 2011/12/15
Date Diff:
Total Days: 1.42889802083333; Total Hours: 34.2935525; Total Minutes: 2057.61315; Total Seconds:
123456.789; Total Milliseconds: 123456789
*Edited my initial post to clarify how the "Total" properties work.
//use a TimeSpan do something like this
strCurDate = string.Format(DateTime.Now.ToString(), "yyyy/mm/dd");
FileInfo fiUpdateFileFile = null;
fiUpdateFileFile = new FileInfo(YourFile Location + Your FileName);
if (((TimeSpan)(DateTime.Now - fiUpdateFileFile.LastWriteTime)).TotalHours < 24)
{
// do your logic here...
}
// you could also get at DateTime.Now.Date() or Day.. depending on what you want to do
I am working with an old mysql database in which a date is stored (without a time) as a datetime and a time is stored as a string (without a date).
In C# I then have a DateTime with a value like 2010-06-25 12:00:00 AM and a String with a value like 15:02.
What is the most concise way to combine these without a lot of overhead?
I have tried a few methods including:
DateTime NewDateTime = DateTime.Parse(OldDateTime.ToString("yyyy-MM-dd ") + TimeString);
I dislike converting the existing DateTime to a string and appending the time.
I can convert the time string to a date, but then I get today's date and adding it as a number of ticks to the old datetime is incorrect.
Note: Don't worry about validation, it is done elsewhere. The time is represented using 24-hour format without seconds.
You can use TimeSpan.Parse to parse the time, and then add the result to the date:
DateTime newDateTime = oldDateTime.Add(TimeSpan.Parse(timeString));
var dt = new DateTime(2010, 06, 26); // time is zero by default
var tm = TimeSpan.Parse("01:16:50");
var fullDt = dt + tm; // 2010-06-26 01:16:50
I used something similar to what simendsjo says, except I continued to have it as a DateTime
DateTime date = Convert.ToDateTime(txtTrainDate.Text);
DateTime time = Convert.ToDateTime(ddTrainTime.SelectedValue);
DateTime dtCOMPLTDTTM = new DateTime(date.Year, date.Month, date.Day, time.Hour, time.Minute, time.Second);
I think you're worrying about the string conversion too much. By combining the 2 string elements together you are saving further date string parsing anyway which will most likely be more expensive.
Is this going to be repeated a lot of times or a simple step in a larger process?
I am fairly sure you could combine and convert these values into a timestamp using SQL.