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Converting a String type to specific DateTime

How do you convert a string such as "2017-12-25T03:31:03.150-08:00" into a DateTime?

DateTime myDate = DateTime.ParseExact("2009-05-08 14:40:52,531", "yyyy-MM-dd HH:mm:ss,fff",
System.Globalization.CultureInfo.InvariantCulture);

When you have to follow a predefined pattern while parsing string to DateTime, use DateTime.ParseExact (or DateTime.TryParseExact); in your case:
string source = "2017-12-25T03:31:03.150-08:00";
DateTime result = DateTime.ParseExact(source,
"yyyy-M-d'T'HH:mm:ss.fffzzz",
CultureInfo.InvariantCulture);
I've put M-d (not MM-dd) since the example in the question doesn't provide enough information if month and day must have leading zeroes or not.

How do I format a DateTime in a different format?

I have a string representing a date in a certain format, that I wish to format differently. Someone told me to use DateTime.(Try)ParseExact, so I did:
var dateString = "2016-02-26";
var formatString = "dd/MM/yyyy";
var parsedDate = DateTime.ParseExact(dateString, formatString, null);
You see, I want to format the date as dd/MM/yyyy, so 26/02/2016. However, this code throws a FormatException:
String was not recognized as a valid DateTime.
How can I format a DateTime differently?

First of all, DateTimes have no format. A DateTime holds a moment in time and a flag indicating whether that moment is Local, Utc or Unspecified.
The only moment a DateTime gets formatted, is when you output its value as a string.
The format string you provide to (Try)ParseExact is the format that the date(time) string to parse is in. See MSDN: Custom Date and Time Format Strings to learn how you can write your own format string.
So the code you're looking for to parse that string is this, and again, make sure the format string matches the format of the input date string exactly:
var dateString = "2016-02-26";
var formatString = "yyyy-MM-dd";
var parsedDate = DateTime.ParseExact(dateString, formatString, null);
Now parsedDate holds a DateTime value that you can output in your desired format (and note that you'll have to escape the /, as it'll be interpreted as "the date separator character for the current culture", as explained in above MSDN link):
var formattedDate = parsedDate.ToString("dd\\/MM\\/yyyy");
This will format the date in the desired format:
26/02/2016

You can use this for String date
DateTime.ParseExact(dateString, format, provider);
and for provider value
CultureInfo provider = CultureInfo.InvariantCulture;
as mentioned in Microsoft documentation

Convert a string to datetime format in asp .net

I have a date time string "12-24-2013 15:19:29" which is in "MM-dd-yyyy HH:mm:ss". I want to convert this string to datetime. But the format should not change.ie, it should be the same "MM-dd-yyyy HH:mm:ss" format.
When I used following method,
DateTime dt2 = DateTime.ParseExact(date31strin, "MM-dd-yyyy HH:mm:ss", CultureInfo.InvariantCulture);
the format is changed to "dd-MM-yyyy HH:mm:ss". I have tried some other method also, but still getting this same format.

First, you should be parsing the string to a DateTime and then format it to the second format using ToString() method.
//Convert your string to a DateTime
DateTime dt2 = DateTime.ParseExact(date31strin,
"MM-dd-yyyy HH:mm:ss", CultureInfo.InvariantCulture);
//If you want to change the format
string secondFormat = dt2.ToString("Second format string");
Note: Date is a Date and it does not have a format. If you need to convert the string to a DateTime, first line of code is enough

You are not changing the format.
You are parsing a string into a DateTime object which does not have a format.
When you decide to present the DateTime, you can format it any way you wish.

to parse String to DateTime use method DateTime.TryParse (http://msdn.microsoft.com/cs-cz/library/ch92fbc1%28v=vs.110%29.aspx) and then use DateTime formating (http://msdn.microsoft.com/en-us/library/az4se3k1%28v=vs.110%29.aspx) to output to aspx page

//frndzz if you are using j query and you don't convert date in(MM/dd/yyyy) to //(dd/MM/yyyy) then this code will help you
// i try it and i get the answer
string sd=txtmydate.Text //sd=04/27/2015 (MM-dd-yyyy) format
string [] sdate = sd.Split('-');
string fd = sdate[1];
fd=string.Concat(sdate[1],"-",sdate[0],"-",sdate[2]);
DateTime dt = Convert.ToDateTime(fd);
txtshow.Text = dt.ToString("dd/MM/yyyy");
//txtshow will show you date as 27-04-2015 (dd/MM/yyyy) format
thanks

How to convert string to DateTime:
string iDate = "Absent";
aEmployeeAttendence.Intime = DateTime.Parse(iDate);
//aEmployeeAttendence (object)
//Intime (field)

Convert to dateTime from string (arabic culture to english)

string strHijdt ="29-02-1435";
DateTime hdt = DateTime.ParseExact(strHijdt, "dd/MMM/yyyy HH:MI24",
CultureInfo.InvariantCulture);
Getting error while convert to string("29-02-1435") to datetime

2/1435 has 28 days only
so, below will work
string aa="28-02-1435";
DateTime hdt = DateTime.ParseExact(aa, "dd-MM-yyyy", CultureInfo.InvariantCulture);
Console.WriteLine(hdt.ToLongDateString());
DEMO
since you have given input as 29-02-1435 even you provide correct date time format (dd-MM-yyyy) you will get error for the invalid date

Two problems here:
1. As mentioned above, expected format for does not match string (there is no time, different separator)
2. If your date string is in Hijri calendar, you should either provide correct culture explicitly or use system culture (pass null for IFormatProvider):
string strHijdt = "29-02-1435";
var culture = CultureInfo.GetCultureInfo("ar-SA");
DateTime hdt = DateTime.ParseExact(strHijdt, "dd-MM-yyyy", culture);

Convert YYYYMMDD string to MM/DD/YYYY string

I have a date that is stored as a string in the format YYYYDDMM. I would like to display that value in a 'MM/DD/YYYY' format. I am programming in c#. The current code that I am using is as follows:
txtOC31.Text = dr["OC31"].ToString().Trim();
strOC31date = dr["OC31DATE"].ToString().Trim();
DateTime date31 = DateTime.Parse(strOC31date);
strOC31date = String.Format("{0:MM/dd/yyyy}", date31);
However, I am getting an error because the YYYYMMDD string (strOC31date) is not being recognized as a valid datetime.

DateTime.ParseExact with an example
string res = "20120708";
DateTime d = DateTime.ParseExact(res, "yyyyddMM", CultureInfo.InvariantCulture);
Console.WriteLine(d.ToString("MM/dd/yyyy"));

Use ParseExact() (MSDN) when the string you are trying to parse is not in one of the standard formats. This will allow you to parse a custom format and will be slightly more efficient (I compare them in a blog post here).
DateTime date31 = DateTime.ParseExact(strOC31date, "yyyyMMdd", null);
Passing null for the format provider will default to DateTimeFormatInfo.CurrentInfo and is safe, but you probably want the invariant culture instead:
DateTime date31 = DateTime.ParseExact(strOC31date, "yyyyMMdd", DateTimeFormatInfo.InvariantInfo);
Then your code will work.

Instead of DateTime.Parse(strOC31date); use DateTime.ParseExact() method, which takes format as one of the parameters.

You want the method DateTime.ParseExact.
DateTime date31 = DateTime.ParseExact(strOC31date, "yyyyddMM", CultureInfo.InvariantCulture);