How can I change only the time in my DateTime variable "s"?
DateTime s = some datetime;
You can't change a DateTime value - it's immutable. However, you can change the variable to have a new value. The easiest way of doing that to change just the time is to create a TimeSpan with the relevant time, and use the DateTime.Date property:
DateTime s = ...;
TimeSpan ts = new TimeSpan(10, 30, 0);
s = s.Date + ts;
s will now be the same date, but at 10.30am.
Note that DateTime disregards daylight saving time transitions, representing "naive" Gregorian time in both directions (see Remarks section in the DateTime docs). The only exceptions are .Now and .Today: they retrieve current system time which reflects these events as they occur.
This is the kind of thing which motivated me to start the Noda Time project, which is now production-ready. Its ZonedDateTime type is made "aware" by linking it to a tz database entry.
Alright I'm diving in with my suggestion, an extension method:
public static DateTime ChangeTime(this DateTime dateTime, int hours, int minutes, int seconds, int milliseconds)
{
return new DateTime(
dateTime.Year,
dateTime.Month,
dateTime.Day,
hours,
minutes,
seconds,
milliseconds,
dateTime.Kind);
}
Then call:
DateTime myDate = DateTime.Now.ChangeTime(10,10,10,0);
It's important to note that this extension returns a new date object, so you can't do this:
DateTime myDate = DateTime.Now;
myDate.ChangeTime(10,10,10,0);
But you can do this:
DateTime myDate = DateTime.Now;
myDate = myDate.ChangeTime(10,10,10,0);
s = s.Date.AddHours(x).AddMinutes(y).AddSeconds(z);
In this way you preserve your date, while inserting a new hours, minutes and seconds part to your liking.
one liner
var date = DateTime.Now.Date.Add(new TimeSpan(4, 30, 0));
would bring back todays date with a time of 4:30:00, replace DateTime.Now with any date object
DateTime is an immutable type, so you can't change it.
However, you can create a new DateTime instance based on your previous instance. In your case, it sounds like you need the Date property, and you can then add a TimeSpan that represents the time of day.
Something like this:
var newDt = s.Date + TimeSpan.FromHours(2);
If you already have the time stored in another DateTime object you can use the Add method.
DateTime dateToUse = DateTime.Now();
DateTime timeToUse = new DateTime(2012, 2, 4, 10, 15, 30); //10:15:30 AM
DateTime dateWithRightTime = dateToUse.Date.Add(timeToUse.TimeOfDay);
The TimeOfDay property is a TimeSpan object and can be passed to the Add method. And since we use the Date property of the dateToUse variable we get just the date and add the time span.
Simplest solution :
DateTime s = //some Datetime that you want to change time for 8:36:44 ;
s = new DateTime(s.Year, s.Month, s.Day, 8, 36, 44);
And if you need a specific Date and Time Format :
s = new DateTime(s.Year, s.Month, s.Day, 8, 36, 44).ToString("yyyy-MM-dd h:mm:ss");
You can assign an initial value to a new DateTime value in many different ways:
Extension Method
Extension method DateTime
public static DateTime ChangeTime(this DateTime dateTime, int hours, int minutes, int seconds = default, int milliseconds = default)
{
return new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, hours, minutes, seconds, milliseconds, dateTime.Kind);
}
then using ChangeTime:
DateTime datetime = DateTime.Now; //Your DateTime
datetime = datetime.ChangeTime(12, 20, 10);
using the Add methods
DateTime datetime = DateTime.Now; //Your DateTime
datetime = datetime.Date.AddHours(12).AddMinutes(20).AddSeconds(10);
using the Timespan
DateTime datetime = DateTime.Now; //Your DateTime
datetime = datetime.Date.Add(new TimeSpan(12, 20, 10));
using initial value
DateTime datetime = DateTime.Now;
datetime = new DateTime(datetime.Year, datetime.Month, datetime.Day, 12, 20, 10);
DateTime ts = DateTime.Now;
ts = new DateTime ( ts.Year, ts.Month, ts.Day, 0, 0, 0 ) ;
Console.WriteLine ( "Today = " + ts.ToString("M/dd/yy HH:mm:ss") ) ;
Executed:
Today = 9/04/15 00:00:00
Happened upon this post as I was looking for the same functionality this could possibly do what the guy wanted. Take the original date and replace the time part
DateTime dayOpen = DateTime.Parse(processDay.ToShortDateString() + " 05:00 AM");
Adding .Date to your date sets it to midnight (00:00).
MyDate.Date
Note The equivavalent SQL is CONVERT(DATETIME, CONVERT(DATE, #MyDate))
What makes this method so good is that it's both quick to type and easy to read. A bonus is that there is no conversion from strings.
I.e. To set today's date to 23:30, use:
DateTime.Now.Date.AddHours(23).AddMinutes(30)
You can of course replace DateTime.Now or MyDate with any date of your choice.
Since DateTime is immutable, a new instance has to be created when a date component needs to be changed. Unfortunately, there is no built-in functionality to set individual components of a DateTime instance.
Using the following extension methods
public static DateTime SetPart(this DateTime dateTime, int? year, int? month, int? day, int? hour, int? minute, int? second)
{
return new DateTime(
year ?? dateTime.Year,
month ?? dateTime.Month,
day ?? dateTime.Day,
hour ?? dateTime.Hour,
minute ?? dateTime.Minute,
second ?? dateTime.Second
);
}
public static DateTime SetYear(this DateTime dateTime, int year)
{
return dateTime.SetPart(year, null, null, null, null, null);
}
public static DateTime SetMonth(this DateTime dateTime, int month)
{
return dateTime.SetPart(null, month, null, null, null, null);
}
public static DateTime SetDay(this DateTime dateTime, int day)
{
return dateTime.SetPart(null, null, day, null, null, null);
}
public static DateTime SetHour(this DateTime dateTime, int hour)
{
return dateTime.SetPart(null, null, null, hour, null, null);
}
public static DateTime SetMinute(this DateTime dateTime, int minute)
{
return dateTime.SetPart(null, null, null, null, minute, null);
}
public static DateTime SetSecond(this DateTime dateTime, int second)
{
return dateTime.SetPart(null, null, null, null, null, second);
}
you can set individual DateTime components like
var now = DateTime.Now;
now.SetSecond(0);
When you construct your DateTime object, use a constructor that allows you to specify time:
var myDateTime = new DateTime(2000, 01, 01, 13, 37, 42); // 2000-01-01 13:37:42
If you already have a DateTime object and wish to change the time, uou can add minutes, hours or seconds to your DateTime using simple methods:
var myDateTime = new DateTime(2000, 01, 01); // 2000-01-01 00:00:00
myDateTime = myDateTime.AddHours(13); // 2000-01-01 13:00:00
myDateTime = myDateTime.AddMinutes(37); // 2000-01-01 13:37:00
myDateTime = myDateTime.AddSecounds(42); // 2000-01-01 13:37:42
Notice how we have to "save" the result from each method call to the myDateTime variable. This is because the DateTime is immutable, and its methods simply create new instances with the extra hours/minutes/seconds added.
If you need to add both hours and minutes (and/or seconds) and the same time, you can simplify the code by adding a TimeSpan to the original DateTime instead:
var myDateTime = new DateTime(2000, 01, 01); // 2000-01-01 00:00:00
myDateTime += new TimeSpan(13, 37, 42); // 2000-01-01 13:37:42
If you want to set absolute hours/minues/seconds, rather than adding to the existing values, you can use the aforementioned DateTime constructor, and reuse values for year/month/day from earlier:
myDateTime = new DateTime(myDateTime.Year, myDateTime.Month, myDateTime.Day,
20, 33, 19) // 2000-01-01 20:33:19
In fact, you can't change the time once it's created.
But you can create it easily with many constructors:
https://learn.microsoft.com/en-us/dotnet/api/system.datetime.-ctor?view=netframework-4.7.2
For example, if you want to create a DateTime changing Seconds, you can just do this:
DateTime now = DateTime.Now;
DateTime secondschanged = new DateTime(now.Year, now.Month, now.Day, now.Hour, now.Minute, yourseconds);
If you have a DateTime like 2014/02/05 18:19:51 and want just 2014/02/05, you can do that:
_yourDateTime = new DateTime(_yourDateTime.Year, _yourDateTime.Month, _yourDateTime.Day)
Use Date.Add and add a New TimeSpan with the new time you want to add
DateTime dt = DateTime.Now
dt.Date.Add(new TimeSpan(12,15,00))
int year = 2012;
int month = 12;
int day = 24;
int hour = 0;
int min = 0;
int second = 23;
DateTime dt = new DateTime(year, month, day, hour, min, second);
To set end of a day:
date = new DateTime(date.Year, date.Month, date.Day, 23, 59, 59);
Here is a method you could use to do it for you, use it like this
DateTime newDataTime = ChangeDateTimePart(oldDateTime, DateTimePart.Seconds, 0);
Here is the method, there is probably a better way, but I just whipped this up:
public enum DateTimePart { Years, Months, Days, Hours, Minutes, Seconds };
public DateTime ChangeDateTimePart(DateTime dt, DateTimePart part, int newValue)
{
return new DateTime(
part == DateTimePart.Years ? newValue : dt.Year,
part == DateTimePart.Months ? newValue : dt.Month,
part == DateTimePart.Days ? newValue : dt.Day,
part == DateTimePart.Hours ? newValue : dt.Hour,
part == DateTimePart.Minutes ? newValue : dt.Minute,
part == DateTimePart.Seconds ? newValue : dt.Second
);
}
I have just come across this post because I had a similar issue whereby I wanted to set the time for an Entity Framework object in MVC that gets the date from a view (datepicker) so the time component is 00:00:00 but I need it to be the current time. Based on the answers in this post I came up with:
myEntity.FromDate += DateTime.Now.TimeOfDay;
//The fastest way to copy time
DateTime justDate = new DateTime(2011, 1, 1); // 1/1/2011 12:00:00AM the date you will be adding time to, time ticks = 0
DateTime timeSource = new DateTime(1999, 2, 4, 10, 15, 30); // 2/4/1999 10:15:30AM - time tick = x
justDate = new DateTime(justDate.Date.Ticks + timeSource.TimeOfDay.Ticks);
Console.WriteLine(justDate); // 1/1/2011 10:15:30AM
Console.Read();
DateTime s;
//s = datevalue
s = s.AddMilliseconds(10);
s = s.AddMinutes(10);
s = s.AddSeconds(10);
s = s.AddHours(10);
you could add +ve/-ve values in parameter.
s.Add(new TimeSpan(1, 1, 1));
Doesn't that fix your problems??
Dateime dt = DateTime.Now;
dt = dt.AddSeconds(10);
I prefer this:
DateTime s = //get some datetime;
s = new DateTime(s.Year, s.Month,s.Day,s.Hour,s.Minute,0);
Using an extencion to DateTime:
public enum eTimeFragment
{
hours,
minutes,
seconds,
milliseconds
}
public static DateTime ClearTimeFrom(this DateTime dateToClear, eTimeFragment etf)
{
DateTime dtRet = dateToClear;
switch (etf)
{
case eTimeFragment.hours:
dtRet = dateToClear.Date;
break;
case eTimeFragment.minutes:
dtRet = dateToClear.AddMinutes(dateToClear.Minute * -1);
dtRet = dtRet.ClearTimeFrom(eTimeFragment.seconds);
break;
case eTimeFragment.seconds:
dtRet = dateToClear.AddSeconds(dateToClear.Second * -1);
dtRet = dtRet.ClearTimeFrom(eTimeFragment.milliseconds);
break;
case eTimeFragment.milliseconds:
dtRet = dateToClear.AddMilliseconds(dateToClear.Millisecond * -1);
break;
}
return dtRet;
}
Use like this:
Console.WriteLine (DateTime.Now.ClearTimeFrom(eTimeFragment.hours))
this has to return:
2016-06-06 00:00:00.000
What's wrong with DateTime.AddSeconds method where you can add or substract seconds?
Try this one
var NewDate = Convert.ToDateTime(DateTime.Now.ToString("dd/MMM/yyyy")+" "+"10:15 PM")/*Add your time here*/;
The best solution is:
currdate.AddMilliseconds(currdate.Millisecond * -1).AddSeconds(currdate.Second * -1).AddMinutes(currdate.Minute * -1).AddHours(currdate.Hour * -1);
here is a ghetto way, but it works :)
DateTime dt = DateTime.Now; //get a DateTime variable for the example
string newSecondsValue = "00";
dt = Convert.ToDateTime(dt.ToString("MM/dd/yyyy hh:mm:" + newSecondsValue));
Related
I want to get the first day and last day of the month where a given date lies in. The date comes from a value in a UI field.
If I'm using a time picker I could say
var maxDay = dtpAttendance.MaxDate.Day;
But I'm trying to get it from a DateTime object. So if I have this...
DateTime dt = DateTime.today;
How to get first day and last day of the month from dt?
DateTime structure stores only one value, not range of values. MinValue and MaxValue are static fields, which hold range of possible values for instances of DateTime structure. These fields are static and do not relate to particular instance of DateTime. They relate to DateTime type itself.
Suggested reading: static (C# Reference)
UPDATE: Getting month range:
DateTime date = ...
var firstDayOfMonth = new DateTime(date.Year, date.Month, 1);
var lastDayOfMonth = firstDayOfMonth.AddMonths(1).AddDays(-1);
UPDATE: From comments (#KarlGjertsen & #SergeyBerezovskiy)
DateTime date = ...
var firstDayOfMonth = new DateTime(date.Year, date.Month, 1);
var lastDayOfMonth = firstDayOfMonth.AddMonths(1).AddSeconds(-1);
//OR
var lastDayOfMonth = firstDayOfMonth.AddMonths(1).AddTicks(-1);
This is more a long comment on #Sergey and #Steffen's answers. Having written similar code myself in the past I decided to check what was most performant while remembering that clarity is important too.
Result
Here is an example test run result for 10 million iterations:
2257 ms for FirstDayOfMonth_AddMethod()
2406 ms for FirstDayOfMonth_NewMethod()
6342 ms for LastDayOfMonth_AddMethod()
4037 ms for LastDayOfMonth_AddMethodWithDaysInMonth()
4160 ms for LastDayOfMonth_NewMethod()
4212 ms for LastDayOfMonth_NewMethodWithReuseOfExtMethod()
2491 ms for LastDayOfMonth_SpecialCase()
Code
I used LINQPad 4 (in C# Program mode) to run the tests with compiler optimization turned on. Here is the tested code factored as Extension methods for clarity and convenience:
public static class DateTimeDayOfMonthExtensions
{
public static DateTime FirstDayOfMonth_AddMethod(this DateTime value)
{
return value.Date.AddDays(1 - value.Day);
}
public static DateTime FirstDayOfMonth_NewMethod(this DateTime value)
{
return new DateTime(value.Year, value.Month, 1);
}
public static DateTime LastDayOfMonth_AddMethod(this DateTime value)
{
return value.FirstDayOfMonth_AddMethod().AddMonths(1).AddDays(-1);
}
public static DateTime LastDayOfMonth_AddMethodWithDaysInMonth(this DateTime value)
{
return value.Date.AddDays(DateTime.DaysInMonth(value.Year, value.Month) - value.Day);
}
public static DateTime LastDayOfMonth_SpecialCase(this DateTime value)
{
return value.AddDays(DateTime.DaysInMonth(value.Year, value.Month) - 1);
}
public static int DaysInMonth(this DateTime value)
{
return DateTime.DaysInMonth(value.Year, value.Month);
}
public static DateTime LastDayOfMonth_NewMethod(this DateTime value)
{
return new DateTime(value.Year, value.Month, DateTime.DaysInMonth(value.Year, value.Month));
}
public static DateTime LastDayOfMonth_NewMethodWithReuseOfExtMethod(this DateTime value)
{
return new DateTime(value.Year, value.Month, value.DaysInMonth());
}
}
void Main()
{
Random rnd = new Random();
DateTime[] sampleData = new DateTime[10000000];
for(int i = 0; i < sampleData.Length; i++) {
sampleData[i] = new DateTime(1970, 1, 1).AddDays(rnd.Next(0, 365 * 50));
}
GC.Collect();
System.Diagnostics.Stopwatch sw = System.Diagnostics.Stopwatch.StartNew();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].FirstDayOfMonth_AddMethod();
}
string.Format("{0} ms for FirstDayOfMonth_AddMethod()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].FirstDayOfMonth_NewMethod();
}
string.Format("{0} ms for FirstDayOfMonth_NewMethod()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_AddMethod();
}
string.Format("{0} ms for LastDayOfMonth_AddMethod()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_AddMethodWithDaysInMonth();
}
string.Format("{0} ms for LastDayOfMonth_AddMethodWithDaysInMonth()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_NewMethod();
}
string.Format("{0} ms for LastDayOfMonth_NewMethod()", sw.ElapsedMilliseconds).Dump();
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_NewMethodWithReuseOfExtMethod();
}
string.Format("{0} ms for LastDayOfMonth_NewMethodWithReuseOfExtMethod()", sw.ElapsedMilliseconds).Dump();
for(int i = 0; i < sampleData.Length; i++) {
sampleData[i] = sampleData[i].FirstDayOfMonth_AddMethod();
}
GC.Collect();
sw.Restart();
for(int i = 0; i < sampleData.Length; i++) {
DateTime test = sampleData[i].LastDayOfMonth_SpecialCase();
}
string.Format("{0} ms for LastDayOfMonth_SpecialCase()", sw.ElapsedMilliseconds).Dump();
}
Analysis
I was surprised by some of these results.
Although there is not much in it the FirstDayOfMonth_AddMethod was slightly faster than FirstDayOfMonth_NewMethod in most runs of the test. However, I think the latter has a slightly clearer intent and so I have a preference for that.
LastDayOfMonth_AddMethod was a clear loser against LastDayOfMonth_AddMethodWithDaysInMonth, LastDayOfMonth_NewMethod and LastDayOfMonth_NewMethodWithReuseOfExtMethod. Between the fastest three there is nothing much in it and so it comes down to your personal preference. I choose the clarity of LastDayOfMonth_NewMethodWithReuseOfExtMethod with its reuse of another useful extension method. IMHO its intent is clearer and I am willing to accept the small performance cost.
LastDayOfMonth_SpecialCase assumes you are providing the first of the month in the special case where you may have already calculated that date and it uses the add method with DateTime.DaysInMonth to get the result. This is faster than the other versions, as you would expect, but unless you are in a desperate need for speed I don't see the point of having this special case in your arsenal.
Conclusion
Here is an extension method class with my choices and in general agreement with #Steffen I believe:
public static class DateTimeDayOfMonthExtensions
{
public static DateTime FirstDayOfMonth(this DateTime value)
{
return new DateTime(value.Year, value.Month, 1);
}
public static int DaysInMonth(this DateTime value)
{
return DateTime.DaysInMonth(value.Year, value.Month);
}
public static DateTime LastDayOfMonth(this DateTime value)
{
return new DateTime(value.Year, value.Month, value.DaysInMonth());
}
}
If you have got this far, thank you for time! Its been fun :¬). Please comment if you have any other suggestions for these algorithms.
Getting month range with .Net API (just another way):
DateTime date = ...
var firstDayOfMonth = new DateTime(date.Year, date.Month, 1);
var lastDayOfMonth = new DateTime(date.Year, date.Month, DateTime.DaysInMonth(date.Year, date.Month));
"Last day of month" is actually "First day of *next* month, minus 1". So here's what I use, no need for "DaysInMonth" method:
public static DateTime FirstDayOfMonth(this DateTime value)
{
return new DateTime(value.Year, value.Month, 1);
}
public static DateTime LastDayOfMonth(this DateTime value)
{
return value.FirstDayOfMonth()
.AddMonths(1)
.AddMinutes(-1);
}
NOTE:
The reason I use AddMinutes(-1), not AddDays(-1) here is because usually you need these date functions for reporting for some date-period, and when you build a report for a period, the "end date" should actually be something like Oct 31 2015 23:59:59 so your report works correctly - including all the data from last day of month.
I.e. you actually get the "last moment of the month" here. Not Last day.
OK, I'm going to shut up now.
DateTime dCalcDate = DateTime.Now;
dtpFromEffDate.Value = new DateTime(dCalcDate.Year, dCalcDate.Month, 1);
dptToEffDate.Value = new DateTime(dCalcDate.Year, dCalcDate.Month, DateTime.DaysInMonth(dCalcDate.Year, dCalcDate.Month));
Here you can add one month for the first day of current month than delete 1 day from that day.
DateTime now = DateTime.Now;
var startDate = new DateTime(now.Year, now.Month, 1);
var endDate = startDate.AddMonths(1).AddDays(-1);
If you only care about the date
var firstDay = new DateTime(date.Year, date.Month, 1, 0, 0, 0, date.Kind);
var lastDay = new DateTime(date.Year, date.Month, 1, 0, 0, 0, date.Kind).AddMonths(1).AddDays(-1);
If you want to preserve time
var firstDay = new DateTime(date.Year, date.Month, 1, date.Hour, date.Minute, date.Second, date.Kind);
var lastDay = new DateTime(date.Year, date.Month, 1, date.Hour, date.Minute, date.Second, date.Kind).AddMonths(1).AddDays(-1);
Try this one:
string strDate = DateTime.Now.ToString("MM/01/yyyy");
The accepted answer here does not take into account the Kind of the DateTime instance. For example if your original DateTime instance was a UTC Kind then by making a new DateTime instance you will be making an Unknown Kind instance which will then be treated as local time based on server settings. Therefore the more proper way to get the first and last date of the month would be this:
var now = DateTime.UtcNow;
var first = now.Date.AddDays(-(now.Date.Day - 1));
var last = first.AddMonths(1).AddTicks(-1);
This way the original Kind of the DateTime instance is preserved.
I used this in my script(works for me) but I needed a full date without the need of trimming it to only the date and no time.
public DateTime GetLastDayOfTheMonth()
{
int daysFromNow = DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month) - (int)DateTime.Now.Day;
return DateTime.Now.AddDays(daysFromNow);
}
For Persian culture
PersianCalendar pc = new PersianCalendar();
var today = pc.GetDayOfMonth(DateTime.Now);
var firstDayOfMonth = pc.GetDayOfMonth(DateTime.Now.AddDays(-(today-1)));
var lastDayOfMonth = pc.GetDayOfMonth(DateTime.Now.AddMonths(1).AddDays(-today));
Console.WriteLine("First day "+ firstDayOfMonth);
Console.WriteLine("Last day " + lastDayOfMonth);
You can do it
DateTime dt = DateTime.Now;
DateTime firstDayOfMonth = new DateTime(dt.Year, date.Month, 1);
DateTime lastDayOfMonth = firstDayOfMonth.AddMonths(1).AddDays(-1);
Give this a try. It basically calculates the number of days that has passed on DateTime.Now, then subtracts one from that and uses the new value to find the first of the current month. From there it uses that DateTime and uses .AddMonths(-1) to get the first of the previous month.
Getting the last day of last month does basically the same thing except it adds one to number of days in the month and subtracts that value from DateTime.Now.AddDays, giving you the last day of the previous month.
int NumberofDays = DateTime.Now.Day;
int FirstDay = NumberofDays - 1;
int LastDay = NumberofDays + 1;
DateTime FirstofThisMonth = DateTime.Now.AddDays(-FirstDay);
DateTime LastDayOfLastMonth = DateTime.Now.AddDays(-LastDay);
DateTime CheckLastMonth = FirstofThisMonth.AddMonths(-1);
You can try this for get current month first day;
DateTime.Now.AddDays(-(DateTime.Now.Day-1))
and assign it a value.
Like this:
dateEndEdit.EditValue = DateTime.Now;
dateStartEdit.EditValue = DateTime.Now.AddDays(-(DateTime.Now.Day-1));
Create an instance of DateTime class
DateTime dateTime = DateTime.Now;
If you want to get the last day of the month you can do this
int lastDayOfMonth = DateTime.DaysInMonth(caducidadPuntos.Year, caducidadPuntos.Month);
If you want to get the first day of the month, you can do this
DateTime firstDayMonth = new DateTime(dateTime.Year, dateTime.Month, 1);
We had the requirement of being able to get the start and end of a given dates month, including times, inclusively. We ended up utilizing the aforementioned solutions, huge thanks to everyone here, and combined it into a util class to be able to get the start and end for a given month and year number combination up to the last millisecond. Including what we moved forward with in the event it helps someone else.
The util:
public class DateUtil
{
public static (DateTime startOfMonth, DateTime endOfMonth) GetStartAndEndOfMonth(int month, int year)
{
DateTime startOfMonth = GetStartOfMonth(month, year);
DateTime endOfMonth = GetEndOfMonth(month, year);
return (startOfMonth, endOfMonth);
}
public static DateTime GetStartOfMonth(int month, int year)
{
return new DateTime(year, month, 1).Date;
}
public static DateTime GetEndOfMonth(int month, int year)
{
return new DateTime(year, month, 1).Date.AddMonths(1).AddMilliseconds(-1);
}
}
Usage:
(DateTime startOfMonth, DateTime endOfMonth) = DateUtil.GetStartAndEndOfMonth(2, 2021); // February, 2021
easy way to do it
Begin = new DateTime(DateTime.Now.Year, DateTime.Now.Month,1).ToShortDateString();
End = new DataFim.Text = new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month)).ToShortDateString();
DateTime dCalcDate = DateTime.Now;
var startDate = new DateTime(Convert.ToInt32(Year), Convert.ToInt32(Month), 1);
var endDate = new DateTime(Convert.ToInt32(Year), Convert.ToInt32(Month), DateTime.DaysInMonth((Convert.ToInt32(Year)), Convert.ToInt32(Month)));
How to compare two DateTime to seconds?
var date1 = DateTime.Now;
var date2 = new DateTime (1992, 6, 6);
var seconds = (date1 - date2).TotalSeconds;
Do you mean comparing two DateTime values down to the second? If so, you might want something like:
private static DateTime RoundToSecond(DateTime dt)
{
return new DateTime(dt.Year, dt.Month, dt.Day,
dt.Hour, dt.Minute, dt.Second);
}
...
if (RoundToSecond(dt1) == RoundToSecond(dt2))
{
...
}
Alternatively, to find out whether the two DateTimes are within a second of each other:
if (Math.Abs((dt1 - dt2).TotalSeconds) <= 1)
If neither of these help, please give more detail in the question.
If you subtract one date from another, it returns a TimeSpan which has a TotalSeconds property. So:
double seconds = (Date1 - Date2).TotalSeconds;
DateTime start = DateTime.now;
DateTime end = DateTime.end;
TimeSpan dif = end - start;
dif will be of the form 0:0:0:0 where the third value is seconds.
In my C# app, I pass a string variable that is of format yyyymmdd-yyyymmdd that represents a from and to date. I want to get the start and end times for these dates respectively. Currently I have the below code but was wondering if there was more of an elegant solution?
So for pdr = 20090521-20090523 would get "20090521 00:00:00" and "20090523 23:59:59"
private void ValidateDatePeriod(string pdr, out DateTime startDate,
out DateTime endDate)
{
string[] dates = pdr.Split('-');
if (dates.Length != 2)
{
throw new Exception("Date period is of incorrect format");
}
if (dates[0].Length != 8 || dates[1].Length != 8)
{
throw new Exception("Split date periods are of incorrect format");
}
startDate = DateTime.ParseExact(dates[0] + " 00:00:00",
"yyyyMMdd HH:mm:ss", null);
endDate = DateTime.ParseExact(dates[1] + "23:59:59",
"yyyyMMdd HH::mm:ss", null);
}
I am surprised to see how an incorrect answer received so many upvotes:
The correct version would be as follows:
public static DateTime StartOfDay(this DateTime theDate)
{
return theDate.Date;
}
public static DateTime EndOfDay(this DateTime theDate)
{
return theDate.Date.AddDays(1).AddTicks(-1);
}
You could define two extension methods somewhere, in a utility class like so :
public static DateTime EndOfDay(this DateTime date)
{
return new DateTime(date.Year, date.Month, date.Day, 23, 59, 59, 999);
}
public static DateTime StartOfDay(this DateTime date)
{
return new DateTime(date.Year, date.Month, date.Day, 0, 0, 0, 0);
}
And then use them in code like so :
public DoSomething()
{
DateTime endOfThisDay = DateTime.Now.EndOfDay();
}
If you are only worried about .Net precision...
startDate = DateTime.ParseExact(dates[0], "yyyyMMdd");
endDate = DateTime.ParseExact(dates[1], "yyyyMMdd").AddTicks(-1).AddDays(1);
You really don't need to concatenate extra values onto the string for the time portion.
As an addendum, if you are using this for a query against, for example, a database...
startDate = DateTime.ParseExact(dates[0], "yyyyMMdd");
endDate = DateTime.ParseExact(dates[1], "yyyyMMdd").AddDays(1);
With a query of...
WHERE "startDate" >= #startDate AND "endDate" < #endDate
Then the precision issues noted in the comments won't really matter. The endDate in this case would not be part of the range, but the outside boundary.
The DateTime object has a property called Date which will return just the date portion. (The time portion is defaulted to 12:00 am).
I would recommend as a more elegant solution (IMHO) that if you want to allow any datetime on the last day, then you add 1 day to the date, and compare to allow times greater than or equal to the start date, but strictly less than the end date (plus 1 day).
// Calling code. beginDateTime and endDateTime are already set.
// beginDateTime and endDateTime are inclusive.
// targetDateTime is the date you want to check.
beginDateTime = beginDateTime.Date;
endDateTime = endDateTime.Date.AddDays(1);
if ( beginDateTime <= targetDateTime &&
targetDateTime < endDateTime )
// Do something.
public static class DateTimeExtension {
public static DateTime StartOfTheDay(this DateTime d) => new DateTime(d.Year, d.Month, d.Day, 0, 0,0);
public static DateTime EndOfTheDay(this DateTime d) => new DateTime(d.Year, d.Month, d.Day, 23, 59,59);
}
I use the following in C#
public static DateTime GetStartOfDay(DateTime dateTime)
{
return new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, 0, 0, 0, 0);
}
public static DateTime GetEndOfDay(DateTime dateTime)
{
return new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, 23, 59, 59, 999);
}
Then in MS SQL I do the following:
if datepart(ms, #dateEnd) = 0
set #dateEnd = dateadd(ms, -3, #dateEnd)
This will result in MS SQL time of 23:59:59.997 which is the max time before becoming the next day.
You could simply use:
new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, 23, 59, 59, 999);
Which will work in MS SQL, but this is not as accurate in .Net side.
That's pretty much what I would do, with some small tweaks (really no big deal, just nitpicking):
The TryParse()/TryParseExact() methods should be used which return false instead of throwing exceptions.
FormatException is more specific than Exception
No need to check for Length == 8, because ParseExact()/TryParseExact() will do this
"00:00:00" and "23:59:59" are not needed
return true/false is you were able to parse, instead of throwing an exception (remember to check value returned from this method!)
Code:
private bool ValidateDatePeriod(string pdr, out DateTime startDate,
out DateTime endDate)
{
string[] dates = pdr.Split('-');
if (dates.Length != 2)
{
return false;
}
// no need to check for Length == 8 because the following will do it anyway
// no need for "00:00:00" or "23:59:59" either, I prefer AddDays(1)
if(!DateTime.TryParseExact(dates[0], "yyyyMMdd", null, DateTimeStyles.None, out startDate))
return false;
if(!DateTime.TryParseExact(dates[1], "yyyyMMdd", null, DateTimeStyles.None, out endDate))
return false;
endDate = endDate.AddDays(1);
return true;
}
I think we're doing it wrong. There is no such thing as the end of the day. AddTick(-1) only works under the convention that there are no time intervals smaller than a tick. Which is implementation dependent. Admittedly the question comes with a reference implementation, namely the .Net Framework DateTime class, but still we should take this as a clue that the function we really want is not EndOfDay() but StartOfNextDay()
public static DateTime StartOfNextDay(this DateTime date)
{
return date.Date.AddDays(1);
}
The issue above regarding the few milliseconds can be resolved by querying the database with the next day's start date.
For example:
SELECT * FROM temp WHERE createdDate >= fromDate AND createdDate < toDate
Using the extension methods below you could set the from and to dates to:
DateTimeOffset fromDate = DateTimeOffset.UtcNow.StartOfDay();
DateTimeOffset toDate = DateTimeOffset.UtcNow.EndOfDay();
public static class DateExtentions
{
public static DateTimeOffset StartOfDay(this DateTimeOffset dateTime)
{
return new DateTimeOffset(dateTime.Year, dateTime.Month, dateTime.Day, 0, 0, 0, 0, dateTime.Offset);
}
public static DateTimeOffset EndOfDay(this DateTimeOffset dateTime)
{
return dateTime.StartOfDay().AddDays(1);
}
public static DateTimeOffset StartOfMonth(this DateTimeOffset dateTime)
{
return new DateTimeOffset(dateTime.Year, dateTime.Month, 1, 0, 0, 0, 0, dateTime.Offset);
}
public static DateTimeOffset EndOfMonth(this DateTimeOffset dateTime)
{
return dateTime.StartOfMonth().AddMonths(1);
}
public static DateTimeOffset StartOfYear(this DateTimeOffset dateTime)
{
return new DateTimeOffset(dateTime.Year, 1, 1, 0, 0, 0, 0, dateTime.Offset);
}
public static DateTimeOffset EndOfYear(this DateTimeOffset dateTime)
{
return dateTime.StartOfYear().AddYears(1);
}
}
For SQL Server (version 2008 R2 tested) this ranges works.
StarDate '2016-01-11 00:00:01.990'
EndDate '2016-01-19 23:59:59.990'
Seems like ticks is greater that the last second of day and automatically round to next day. So i test and works, i made a dummy table with two dates for check what values is sql server catching and inserting in the stored procedure those parameters.
In Java 8, you can do it using LocalDate as follows:
LocalDate localDateStart = LocalDate.now();
Date startDate = Date.from(localDateStart.atStartOfDay(ZoneId.systemDefault()).toInstant());
LocalDate localDateEnd = localDateStart.plusDays(1);
Date endDate = Date.from(localDateEnd.atStartOfDay(ZoneId.systemDefault()).toInstant());
I want to increase time to current time.
For example, I have the time of the problem and the expected time to complete them. How can I add to it?
(DateTime.Now.ToShortDateString() + ...)
You can use other variables:
DateTime otherDate = DateTime.Now.AddMinutes(25);
DateTime tomorrow = DateTime.Now.AddHours(25);
You can use the operators +, -, +=, and -= on a DateTime with a TimeSpan argument.
DateTime myDateTime = DateTime.Parse("24 May 2009 02:19:00");
myDateTime = myDateTime + new TimeSpan(1, 1, 1);
myDateTime = myDateTime - new TimeSpan(1, 1, 1);
myDateTime += new TimeSpan(1, 1, 1);
myDateTime -= new TimeSpan(1, 1, 1);
Furthermore, you can use a set of "Add" methods
myDateTime = myDateTime.AddYears(1);
myDateTime = myDateTime.AddMonths(1);
myDateTime = myDateTime.AddDays(1);
myDateTime = myDateTime.AddHours(1);
myDateTime = myDateTime.AddMinutes(1);
myDateTime = myDateTime.AddSeconds(1);
myDateTime = myDateTime.AddMilliseconds(1);
myDateTime = myDateTime.AddTicks(1);
myDateTime = myDateTime.Add(new TimeSpan(1, 1, 1));
For a nice overview of even more DateTime manipulations see THIS
You can also add a TimeSpan to a DateTime, as in:
date + TimeSpan.FromHours(8);
Please note that you may add - (minus) sign to find minutes backwards
DateTime begin = new DateTime();
begin = DateTime.ParseExact("21:00:00", "H:m:s", null);
if (DateTime.Now < begin.AddMinutes(-15))
{
//if time is before 19:45:00 show message etc...
}
and time forward
DateTime end = new DateTime();
end = DateTime.ParseExact("22:00:00", "H:m:s", null);
if (DateTime.Now > end.AddMinutes(15))
{
//if time is greater than 22:15:00 do whatever you want
}
What's the best way to trim a DateTime object to a specific precision? For instance, if I have a DateTime with a value of '2008-09-29 09:41:43', but I only want it's precision to be to the minute, is there any better way to do it than this?
private static DateTime TrimDateToMinute(DateTime date)
{
return new DateTime(
date.Year,
date.Month,
date.Day,
date.Hour,
date.Minute,
0);
}
What I would really want is to make it variable so that I could set its precision to the second, minute, hour, or day.
static class Program
{
//using extension method:
static DateTime Trim(this DateTime date, long roundTicks)
{
return new DateTime(date.Ticks - date.Ticks % roundTicks, date.Kind);
}
//sample usage:
static void Main(string[] args)
{
Console.WriteLine(DateTime.Now);
Console.WriteLine(DateTime.Now.Trim(TimeSpan.TicksPerDay));
Console.WriteLine(DateTime.Now.Trim(TimeSpan.TicksPerHour));
Console.WriteLine(DateTime.Now.Trim(TimeSpan.TicksPerMillisecond));
Console.WriteLine(DateTime.Now.Trim(TimeSpan.TicksPerMinute));
Console.WriteLine(DateTime.Now.Trim(TimeSpan.TicksPerSecond));
Console.ReadLine();
}
}
You could use an enumeration
public enum DateTimePrecision
{
Hour, Minute, Second
}
public static DateTime TrimDate(DateTime date, DateTimePrecision precision)
{
switch (precision)
{
case DateTimePrecision.Hour:
return new DateTime(date.Year, date.Month, date.Day, date.Hour, 0, 0);
case DateTimePrecision.Minute:
return new DateTime(date.Year, date.Month, date.Day, date.Hour, date.Minute, 0);
case DateTimePrecision.Second:
return new DateTime(date.Year, date.Month, date.Day, date.Hour, date.Minute, date.Second);
default:
break;
}
}
and expand as required.
I like this method. Someone mentioned it was good to preserve the Date Kind, etc. This accomplishes that because you dont have to make a new DateTime. The DateTime is properly cloned from the original DateTime and it simply subtracts the remainder ticks.
public static DateTime FloorTime(DateTime dt, TimeSpan interval)
{
return dt.AddTicks(-1 * (dt.Ticks % interval.Ticks));
}
usage:
dt = FloorTime(dt, TimeSpan.FromMinutes(5)); // floor to the nearest 5min interval
dt = FloorTime(dt, TimeSpan.FromSeconds(1)); // floor to the nearest second
dt = FloorTime(dt, TimeSpan.FromDays(1)); // floor to the nearest day
There are some good solutions presented here, but when I need to do this, I simply do:
DateTime truncDate;
truncDate = date.Date; // trim to day
truncDate = date.Date + TimeSpan.Parse(string.Format("{0:HH:00:00}", date)); // trim to hour
truncDate = date.Date + TimeSpan.Parse(string.Format("{0:HH:mm}", date)); // trim to minute
truncDate = date.Date + TimeSpan.Parse(string.Format("{0:HH:mm:ss}", date)); // trim to second
Hope it helps.
DateTime dt = new DateTime()
dt = dt.AddSeconds(-dt.Second)
Above code will trim seconds.