Replace date in a DateTime with another date - c#

How do you change the day part of a DateTime structure?
I have a DateTime with the value of 3/31/2009 8:00:00 AM and would like to change it to any other date but the time should be same. I don't need a solution to add day(s), I need to replace it with any arbitrary date.
How do I achieve this?

To construct a DateTime from two other DateTimes, one of which contains the date and one of which contains the time, you can use:
DateTime result = date.Date + time.TimeOfDay;

day = 1
month = 4
year = 2009
Date2 = new DateTime(day,month,year,Date1.Hours,Date1.Minute,Date1.Seconds)

s = s.AddDays(1)

You should use DateTime.AddDays method. Like this:
DateTime s2 = s.AddDays( 1 );

Related

Format Previous month with its year

i don't know how to deal with this...
say currently, it's 2013/11/27, so it will be 2013/10 for previous month.
I searched there's something like (DateTime.Now.Month - 1), but how do I keep track of year please?
and say 2014 January, how do I turn it to 201312?
Thanks.
If I understand correctly, you can use DateTime.AddMonths method like;
DateTime now = DateTime.Now;
now = now.AddMonths(-1);
Console.WriteLine(now.ToString("yyyyMM"));
Output will be;
201310
Here a demonstration.
Use the DateTime.AddMonths method
Use AddMonth method of DateTime class to subtract a month:
var previousMoth = DateTime.Now.AddMonths(-1);
var year = previousMoth.Year;
var month = previousMoth.Month;
var day = previousMoth.Day;

Alternative Datetime.Now with only time (21:10)

I was wondering if there's a method or anything which will provide me the current systemtime without the date. I need to use this in a formula and if i want to use the DateTime.NowI have to String.Split this string before I can convert this to a Int.
example: It's 5pm
I want:
'17:00', '5:00', '1700', '500'
Not:
'17:00 PM 29/03/2013'
A DateTime holds the hour and minutes as properties.
var now = DateTime.Now;
var minutes = now.Minute;
var hours = now.Hour;
why cannot you simply format your date i.e.
string CurrentTime = DateTime.Now.ToString("hh:mm:ttt");
I guess what you are looking for is how to format a DateTime correctly.
Look here or here for how this is done.
You could use TimeOfDay. Basically it extracts the time part of a DateTime:
DateTime now = DateTime.Now;
TimeSpan time = now.TimeOfDay;
Do note that unlike the DateTime.Date property, DateTime.TimeOfDay returns a Timespan, not a DateTime.
for "1700" :
date.ToString('HHMM');
Use the DateTime.ToString method:
DateTime dt = DateTime.Now; // Suppose it is currently 5pm
dt.ToString("HH:mm"); // 17:00
dt.ToString("h:mm"); // 5:00
dt.ToString("HHmm"); // 1700
dt.ToString("hmm"); // 500

How to get yesterday's date in C#

I want to retrieve yesterday's date in my ASP.NET web application using C#.
I've tried searching for a solution but have not had much success. The code I'm using just outputs today's date:
string yr = DateTime.Today.Year.ToString();
string mn = DateTime.Today.Month.ToString();
string dt = DateTime.Today.Day.ToString();
date = string.Format("{0}-{1}-{2}", yr, mn, dt);
How can I get yesterday's date?
Use DateTime.AddDays() method with value of -1
var yesterday = DateTime.Today.AddDays(-1);
That will give you : {6/28/2012 12:00:00 AM}
You can also use
DateTime.Now.AddDays(-1)
That will give you previous date with the current time e.g. {6/28/2012 10:30:32 AM}
The code you posted is wrong.
You shouldn't make multiple calls to DateTime.Today. If you happen to run that code just as the date changes you could get completely wrong results. For example if you ran it on December 31st 2011 you might get "2011-1-1".
Use a single call to DateTime.Today then use ToString with an appropriate format string to format the date as you desire.
string result = DateTime.Today.AddDays(-1).ToString("yyyy-MM-dd");
You don't need to call DateTime.Today multiple times, just use it single time and format the date object in your desire format.. like that
string result = DateTime.Now.Date.AddDays(-1).ToString("yyyy-MM-dd");
OR
string result = DateTime.Today.AddDays(-1).ToString("yyyy-MM-dd");
You will get yesterday date by this following code snippet.
DateTime dtYesterday = DateTime.Now.Date.AddDays(-1);
var yesterday = DateTime.Now.AddDays(-1);
Something like this should work
var yesterday = DateTime.Now.Date.AddDays(-1);
DateTime.Now gives you the current date and time.
If your looking to remove the the time element then adding .Date constrains it to the date only ie time is 00:00:00.
Finally .AddDays(-1) removes 1 day to give you yesterday.
string result = DateTime.Now.Date.AddDays(-1).ToString("yyyy-MM-dd");
DateTime dateTime = DateTime.Now ;
string today = dateTime.DayOfWeek.ToString();
string yesterday = dateTime.AddDays(-1).DayOfWeek.ToString(); //Fetch day i.e. Mon, Tues
string result = dateTime.AddDays(-1).ToString("yyyy-MM-dd");
The above snippet will work. It is also advisable to make single instance of DateTime.Now;
DateTime.Today as it implies is todays date and you need to get the Date a day before so you subtract one day using AddDays(-1);
There are sufficient options available in DateTime to get the formatting like ToShortDateString depending on your culture and you have no need to concatenate them individually.
Also you can have a desirable format in the .ToString() version of the DateTime instance

Join Date and Time to DateTime in C#

I am retrieving data from an iSeries where there is a separate date and time fields. I want to join them into a DateTime field in my C# project. I don't see a way to add just a time to a DateTime field. How would you suggest accomplishing this?
You can do this quite easily:
DateTime dateOnly;
DateTime timeOnly;
...
DateTime combined = dateOnly.Date.Add(timeOnly.TimeOfDay);
TimeOfDay returns a TimeSpan, which you then add to the date.
Edit (thanks to commenters below) - to be safe, use dateOnly.Date to ensure the date part only.
How are they being stored? Assuming that the date portion is being stored as a DateTime of midnight of the day in question and the time is a TimeSpan, you can just add them.
DateTime date = ...;
TimeSpan time = ...;
DateTime result = date + time;
You could easily construct a TimeSpan from your "time" field.
Once you have that, just do:
TimeSpan time = GetTimeFieldData();
dateField = dateField.Add(time);
Datetime date = new DateTime(Date1.Year, Date1.Month, Date1.Day, Time1.Hour, Time1.Minute, Time1.Second);
You can add a TimeSpan to a DateTime and write something like this.
// inside consuming function
ISeriesObject obj = getMyObject();
DateTime dt = getDate(obj) + getTime(obj);
private DateTime getDate(ISeriesObject obj)
{
//return a DateTime
}
private TimeSpan getTime(ISeriesObject obj)
{
//return a TimeSpan
}
My answer addresses joining two objects of DateOnly and TimeOnly in .NET 6:
DateOnly orderDate = ...
TimeOnly orderTime = ...
DateTime orderDateTime = orderDate.ToDateTime(orderTime);
This should do:
var output = date.Date + time.TimeOfDay;
or
var output = new DateTime(date.Year, date.Month, date.Day,
time.Hour, time.Minute, time.Second);
suppose that both variable date and time are both of Type DateTime
Note that adding the time to the date is not your biggest problem here. As #Reed Copsey mentioned, you just create a DateTime from the date and then .Add the time.
However, you need to make sure that the iSeries date and time (a Unix time most probably) are in the same representation as the .Net representation. Thus, you most probably need to convert it by adding it to a Jan 1, 1970 DateTime as well.
Cant you simply format the date part and time part as separate strings, then join them together? Then you can parse the string back to a DateTime object

DateTime convert to Date and then back to DateTime in C#

I use this to convert DateTime value into Date and then I add 00:00:00 and 23:59:59 to make sure whole day is taken into consideration when counting stuff. I'm pretty sure it's wrong way of doing things. What would be the right way?
DateTime varObliczOd = DateTime.Parse(dateTimeWycenaPortfelaObliczDataOd.Value.ToShortDateString() + " 00:00:00");
DateTime varObliczDo = DateTime.Parse(dateTimeWycenaPortfelaObliczDataDo.Value.ToShortDateString() + " 23:59:59");
if dateTimeWycenaPortfelaObliczDataOd is of type DateTime, You can use:
dateTimeWycenaPortfelaObliczDataOd.Date
to get the date part only (time will be 00:00:00...).
If you want to get the very last tick of the date, you can use:
dateTimeWycenaPortfelaObliczDataOd.Date.AddDays(1).AddTicks(-1)
but you really better work with the next date (.AddDays(1)).
In any case, there is no need to convert to string and back to DateTime.
DateTime objects have a Date property which might be what you need.
You can use the following properties / methods on a DateTime object to get your values :
DateTime varObliczOd = dateTimeWycenaPortfelaObliczDataOd.Date;
DateTime varObliczDo = dateTimeWycenaPortfelaObliczDataOd.AddDayes(1).AddTicks(-1);
It would help to know why you're needing it, but this would work.
DateTime varObliczOd = dateTimeWycenaPortfelaObliczDataOd.Date;
DateTime varObliczDo = varObliczOd.AddDays(1).AddSeconds(-1);
Using the Date attribute and then manipulating them directly to create the required time component - no need to bother with parsing and conversion.
You could use the Date property of the DateTime object to accomplish what you need.
DateTime varObliczOd = dateTimeWycenaPortfelaObliczDataOd.Value.Date;
DateTime varObliczDo = dateTimeWycenaPortfelaObliczDataDo.Value.Date.AddDays(1);
If you really want it to end at 23:59:59 you can do:
DateTime varObliczDo = dateTimeWycenaPortfelaObliczDataDo.Value.Date.AddDays(1).AddSeconds(-1);
Will set varObliczDo to be your ending date with no time plus one day (at midnight). So if dateTimeWycenaPortfelaObliczDataDo was 2010-03-05 16:12:12 it would now be 2010-03-06 00:00:00.
Something like this maybe? I've typed this out of my head, there are probably some mistakes in the code.
DateTime varObliczOd = dateTimeWycenaPortfelaObliczDataOd.AddSeconds(-dateTimeWycenaPortfelaObliczDataOd.Seconds).AddMinutes(-dateTimeWycenaPortfelaObliczDataOd.Minutes).AddHours(-dateTimeWycenaPortfelaObliczDataOd.Hours);
DateTime varObliczDo = new DateTime(dateTimeWycenaPortfelaObliczDataDo.Year, dateTimeWycenaPortfelaObliczDataDo.Month, dateTimeWycenaPortfelaObliczDataDoDay, 23, 59, 59);
DateTime newDate = new DateTime( oldDate.Year, oldDate.Month, oldDate.Day, 23, 59,59 )
DateTime newDate = new DateTime( oldDate.Year, oldDate.Month, oldDate.Day, 0, 0, 0 )
You could work with TimeSpan:
DateTime varObliczOd = dateTimeWycenaPortfelaObliczDataOd - new TimeSpan(dateTimeWycenaPortfelaObliczDataOd.Hours, dateTimeWycenaPortfelaObliczDataOd.Minutes, dateTimeWycenaPortfelaObliczDataOd.Seconds);
Like that you avoid at least the parsing, which can fail depending on the local culture settings.

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