I have date and time in a string formatted like that one:
"2011-03-21 13:26" //year-month-day hour:minute
How can I parse it to System.DateTime?
I want to use functions like DateTime.Parse() or DateTime.ParseExact() if possible, to be able to specify the format of the date manually.
DateTime.Parse() will try figure out the format of the given date, and it usually does a good job. If you can guarantee dates will always be in a given format then you can use ParseExact():
string s = "2011-03-21 13:26";
DateTime dt =
DateTime.ParseExact(s, "yyyy-MM-dd HH:mm", CultureInfo.InvariantCulture);
(But note that it is usually safer to use one of the TryParse methods in case a date is not in the expected format)
Make sure to check Custom Date and Time Format Strings when constructing format string, especially pay attention to number of letters and case (i.e. "MM" and "mm" mean very different things).
Another useful resource for C# format strings is String Formatting in C#
As I am explaining later, I would always favor the TryParse and TryParseExact methods. Because they are a bit bulky to use, I have written an extension method which makes parsing much easier:
var dtStr = "2011-03-21 13:26";
DateTime? dt = dtStr.ToDate("yyyy-MM-dd HH:mm");
Or more simply, if you want to use the date patterns of your current culture implicitly, you can use it like:
DateTime? dt = dtStr.ToDate();
In that case no specific pattern need to be specified.
Unlike Parse, ParseExact etc. it does not throw an exception, and allows you to check via
if (dt.HasValue) { // continue processing } else { // do error handling }
whether the conversion was successful (in this case dt has a value you can access via dt.Value) or not (in this case, it is null).
That even allows to use elegant shortcuts like the "Elvis"-operator ?., for example:
int? year = dtStr?.ToDate("yyyy-MM-dd HH:mm")?.Year;
Here you can also use year.HasValue to check if the conversion succeeded, and if it did not succeed then year will contain null, otherwise the year portion of the date. There is no exception thrown if the conversion failed.
Solution: The .ToDate() extension method
Try it in .NetFiddle
public static class Extensions
{
/// Extension method parsing a date string to a DateTime? <para/>
/// <summary>
/// </summary>
/// <param name="dateTimeStr">The date string to parse</param>
/// <param name="dateFmt">dateFmt is optional and allows to pass
/// a parsing pattern array or one or more patterns passed
/// as string parameters</param>
/// <returns>Parsed DateTime or null</returns>
public static DateTime? ToDate(this string dateTimeStr, params string[] dateFmt)
{
// example: var dt = "2011-03-21 13:26".ToDate(new string[]{"yyyy-MM-dd HH:mm",
// "M/d/yyyy h:mm:ss tt"});
// or simpler:
// var dt = "2011-03-21 13:26".ToDate("yyyy-MM-dd HH:mm", "M/d/yyyy h:mm:ss tt");
const DateTimeStyles style = DateTimeStyles.AllowWhiteSpaces;
if (dateFmt == null)
{
var dateInfo = System.Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat;
dateFmt=dateInfo.GetAllDateTimePatterns();
}
var result = DateTime.TryParseExact(dateTimeStr, dateFmt, CultureInfo.InvariantCulture,
style, out var dt) ? dt : null as DateTime?;
return result;
}
}
Some information about the code
You might wonder, why I have used InvariantCulture calling TryParseExact: This is to force the function to treat format patterns always the same way (otherwise for example "." could be interpreted as decimal separator in English while it is a group separator or a date separator in German). Recall we have already queried the culture based format strings a few lines before so that is okay here.
Update: .ToDate() (without parameters) now defaults to all common date/time patterns of the thread's current culture.
Note that we need the result and dt together, because TryParseExact does not allow to use DateTime?, which we intend to return.
In C# Version 7 you could simplify the ToDate function a bit as follows:
// in C#7 only: "DateTime dt;" - no longer required, declare implicitly
if (DateTime.TryParseExact(dateTimeStr, dateFmt,
CultureInfo.InvariantCulture, style, out var dt)) result = dt;
or, if you like it even shorter:
// in C#7 only: Declaration of result as a "one-liner" ;-)
var result = DateTime.TryParseExact(dateTimeStr, dateFmt, CultureInfo.InvariantCulture,
style, out var dt) ? dt : null as DateTime?;
in which case you don't need the two declarations DateTime? result = null; and DateTime dt; at all - you can do it in one line of code.
(It would also be allowed to write out DateTime dt instead of out var dt if you prefer that).
The old style of C# would have required it the following way (I removed that from the code above):
// DateTime? result = null;
// DateTime dt;
// if (DateTime.TryParseExact(dateTimeStr, dateFmt,
// CultureInfo.InvariantCulture, style, out dt)) result = dt;
I have simplified the code further by using the params keyword: Now you don't need the 2nd overloaded method any more.
Example of usage
var dtStr="2011-03-21 13:26";
var dt=dtStr.ToDate("yyyy-MM-dd HH:mm");
if (dt.HasValue)
{
Console.WriteLine("Successful!");
// ... dt.Value now contains the converted DateTime ...
}
else
{
Console.WriteLine("Invalid date format!");
}
As you can see, this example just queries dt.HasValue to see if the conversion was successful or not. As an extra bonus, TryParseExact allows to specify strict DateTimeStyles so you know exactly whether a proper date/time string has been passed or not.
More Examples of usage
The overloaded function allows you to pass an array of valid formats used for parsing/converting dates as shown here as well (TryParseExact directly supports this), e.g.
string[] dateFmt = {"M/d/yyyy h:mm:ss tt", "M/d/yyyy h:mm tt",
"MM/dd/yyyy hh:mm:ss", "M/d/yyyy h:mm:ss",
"M/d/yyyy hh:mm tt", "M/d/yyyy hh tt",
"M/d/yyyy h:mm", "M/d/yyyy h:mm",
"MM/dd/yyyy hh:mm", "M/dd/yyyy hh:mm"};
var dtStr="5/1/2009 6:32 PM";
var dt=dtStr.ToDate(dateFmt);
If you have only a few template patterns, you can also write:
var dateStr = "2011-03-21 13:26";
var dt = dateStr.ToDate("yyyy-MM-dd HH:mm", "M/d/yyyy h:mm:ss tt");
Advanced examples
You can use the ?? operator to default to a fail-safe format, e.g.
var dtStr = "2017-12-30 11:37:00";
var dt = (dtStr.ToDate()) ?? dtStr.ToDate("yyyy-MM-dd HH:mm:ss");
In this case, the .ToDate() would use common local culture date formats, and if all these failed, it would try to use the ISO standard format "yyyy-MM-dd HH:mm:ss" as a fallback. This way, the extension function allows to "chain" different fallback formats easily.
You can even use the extension in LINQ, try this out (it's in the .NetFiddle above):
var strDateArray = new[] { "15-01-2019", "15.01.2021" };
var patterns=new[] { "dd-MM-yyyy", "dd.MM.yyyy" };
var dtRange = strDateArray.Select(s => s.ToDate(patterns));
dtRange.Dump();
which will convert the dates in the array on the fly by using the patterns and dump them to the console.
Some background about TryParseExact
Finally, Here are some comments about the background (i.e. the reason why I have written it this way):
I am preferring TryParseExact in this extension method, because you avoid exception handling - you can read in Eric Lippert's article about exceptions why you should use TryParse rather than Parse, I quote him about that topic:2)
This unfortunate design decision1) [annotation: to
let the Parse method throw an exception] was so vexing that of course
the frameworks team implemented TryParse shortly thereafter which does the right thing.
It does, but TryParse and TryParseExact both are still a lot less than comfortable to use: They force you to use an uninitialized variable as an out parameter which must not be nullable and while you're converting you need to evaluate the boolean return value - either you have to use an ifstatement immediately or you have to store the return value in an additional boolean variable so you're able to do the check later. And you can't just use the target variable without knowing if the conversion was successful or not.
In most cases you just want to know whether the conversion was successful or not (and of course the value if it was successful), so a nullable target variable which keeps all the information would be desirable and much more elegant - because the entire information is just stored in one place: That is consistent and easy to use, and much less error-prone.
The extension method I have written does exactly that (it also shows you what kind of code you would have to write every time if you're not going to use it).
I believe the benefit of .ToDate(strDateFormat) is that it looks simple and clean - as simple as the original DateTime.Parse was supposed to be - but with the ability to check if the conversion was successful, and without throwing exceptions.
1) What is meant here is that exception handling (i.e. a try { ... } catch(Exception ex) { ...} block) - which is necessary when you're using Parse because it will throw an exception if an invalid string is parsed - is not only unnecessary in this case but also annoying, and complicating your code. TryParse avoids all this as the code sample I've provided is showing.
2) Eric Lippert is a famous StackOverflow fellow and was working at Microsoft as principal developer on the C# compiler team for a couple of years.
var dateStr = #"2011-03-21 13:26";
var dateTime = DateTime.ParseExact(dateStr, "yyyy-MM-dd HH:mm", CultureInfo.CurrentCulture);
Check out this link for other format strings!
DateTime.Parse() should work fine for that string format. Reference:
http://msdn.microsoft.com/en-us/library/1k1skd40.aspx#Y1240
Is it throwing a FormatException for you?
Put the value of a human-readable string into a .NET DateTime with code like this:
DateTime.ParseExact("April 16, 2011 4:27 pm", "MMMM d, yyyy h:mm tt", null);
You can also use XmlConvert.ToDateString
var dateStr = "2011-03-21 13:26";
var parsedDate = XmlConvert.ToDateTime(dateStr, "yyyy-MM-dd hh:mm");
It is good to specify the date kind, the code is:
var anotherParsedDate = DateTime.ParseExact(dateStr, "yyyy-MM-dd hh:mm", CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal);
More details on different parsing options http://amir-shenodua.blogspot.ie/2017/06/datetime-parsing-in-net.html
The simple and straightforward answer -->
using System;
namespace DemoApp.App
{
public class TestClassDate
{
public static DateTime GetDate(string string_date)
{
DateTime dateValue;
if (DateTime.TryParse(string_date, out dateValue))
Console.WriteLine("Converted '{0}' to {1}.", string_date, dateValue);
else
Console.WriteLine("Unable to convert '{0}' to a date.", string_date);
return dateValue;
}
public static void Main()
{
string inString = "05/01/2009 06:32:00";
GetDate(inString);
}
}
}
/**
* Output:
* Converted '05/01/2009 06:32:00' to 5/1/2009 6:32:00 AM.
* */
Try the following code
Month = Date = DateTime.Now.Month.ToString();
Year = DateTime.Now.Year.ToString();
ViewBag.Today = System.Globalization.CultureInfo.InvariantCulture.DateTimeFormat.GetMonthName(Int32.Parse(Month)) + Year;
DateTime.ParseExact(DateTime, Format, DateTimeFormatInfo.InvariantInfo, DateTimeStyles.AllowLeadingWhite | DateTimeStyles.AllowTrailingWhite)
for example:
DateTime.ParseExact("2011-03-21 13:26", "yyyy-MM-dd hh:mm", DateTimeFormatInfo.InvariantInfo, DateTimeStyles.AllowLeadingWhite | DateTimeStyles.AllowTrailingWhite);
Related
My dateformat is dd/MM/yyyy.
I have a date column in my file with values like 1/08/2019 to 31/08/2019.
But I'm getting the following error when processing that file:
System.FormatException: String was not recognized as a valid DateTime.
at System.DateTimeParse.ParseExact(String s, String format, DateTimeFormatInfo dtfi, DateTimeStyles style)
You've specified in your format string that the days and months must be double digits, but it appears that your input can be single digits.
In order to solve this, you need to specify a single digit in the format string by using a single d for the day portion (and a single M for the month, too).
It's also safe to use a single digit in the format string, since it will handle both single and double digits.
So your format string should look like: "d/M/yyyy"
For example, these all work:
var a = DateTime.ParseExact("1/8/2019", "d/M/yyyy", CultureInfo.CurrentCulture);
var b = DateTime.ParseExact("1/08/2019", "d/M/yyyy", CultureInfo.CurrentCulture);
var c = DateTime.ParseExact("01/8/2019", "d/M/yyyy", CultureInfo.CurrentCulture);
var d = DateTime.ParseExact("01/08/2019", "d/M/yyyy", CultureInfo.CurrentCulture);
difficult to say as you show the error but not the actual code, as you have dates in your file of differennt format, like d/MM/yyyy and dd/MM/yyyy try to use TryParse instead of ParseExact and if the TryParse fails with one format ( d/MM/yyyy ), then do another TryParse with the second format ( dd/MM/yyyy ) that way you should be able to cover both cases.
Again, without seeing the code it is difficult to give more detailed feedback.
also you could use an approach with TryParseExact and multiple format strings, like shown here:
var formatStrings = new string[] { "MM/dd/yyyy hh:mm:ss tt", "yyyy-MM-dd hh:mm:ss" };
if (DateTime.TryParseExact(dt, formatStrings, enUS, DateTimeStyles.None, out dateValue))
return dateValue;
see this SO answer: https://stackoverflow.com/a/17859959/559144
I'm trying to parse 09/01/2015 00:00:00 to the format yyyy-MM-ddThh:mm:ssZ using following method:
DateTime.ParseExact("09/01/2015 00:00:00", "yyyy-MM-ddThh:mm:ssZ", (IFormatProvider)CultureInfo.InvariantCulture);
But I'm getting String was not recognized as a valid DateTime
Can anyone tell me why? I believe 09/01/2015 00:00:00 is a valid DateTime format?
From DateTime.ParseExact
Converts the specified string representation of a date and time to its
DateTime equivalent. The format of the string representation must
match a specified format exactly or an exception is thrown.
In your case, they are not.
I assume your 09 part is day numbers, you can use dd/MM/yyyy HH:mm:ss format instead.
var dt = DateTime.ParseExact("09/01/2015 00:00:00",
"dd/MM/yyyy HH:mm:ss",
CultureInfo.InvariantCulture);
Since CultureInfo already implements IFormatProvider, you don't need to explicitly cast it.
I don't understand this. So it means I first have to correct my string
and secondly I can do a ParseExact(). I thought ParseExact could
handle the given string...
ParseExact is not a magical method that can parse any formatted string you suplied. It can handle only if your string and format perfectly matches based on culture settings you used.
Try this code:
var text = "09/01/2015 00:00:00";
var format = "dd/MM/yyyy HH:mm:ss";
var dt = DateTime.ParseExact(text, format, (IFormatProvider)CultureInfo.InvariantCulture);
You'll notice that the format must structurally match the text you're trying to parse exactly - hence the ParseExact name for the method.
The format does not match, you need to change 09/01/2015 into 2015-01-09 or theyyyy-MM-dd part into dd/MM/yyyy.
The ParseExact-method is no ultimate method that converts ANY dateformat into another one, it is simply to parse a given string into a datetime using the provided format. Thus if your inout does not match this format the method will throw that exception.
As a datetime is internally only a number there is no need to convert one format into another at all, so as long as you know your input-format you can build a date from it which has nothing to do with any formatting which you may need when you want to print that date to your output. In this case you WILL need a formatter.
As most people have stated the error is coming from the fact that the date in string format doesn't match the format you are saying it's in. You are saying that 09/01/2015 00:00:00 is in the format "yyyy-MM-ddThh:mm:ssZ", which it's not, hence the error. To rectify this you need to either alter the format the string is in, or more likely, change the format you are saying the date is in. So change "yyyy-MM-ddThh:mm:ssZ" to "dd/MM/yyyy HH:mm:ss".
In a more long term view how are you arriving at that date? Is it possible that the format may change (input but the user)? If so it might be better to try and avoid the error being thrown and handle it better with TryParseExact. To make use of this best I generally output a nullable DateTime and then check if it's null. If you don't do this then if the parse fails it will simply make the output datetime the minimum value.
Something like this should work:
public DateTime? StringToDate (string dateString, string dateFormat)
{
DateTime? dt;
DateTime.TryParseExact(dateString, dateFormat, null, System.Globalization.DateTimeStyles.None, out dt);
return dt;
}
Then you can use it like this:
DateTime? MyDateTime = StringToDate("09/01/2015 00:00:00", "dd/MM/yyyy HH:mm:ss");
if(MyDateTime != null)
{
//do something
}
Another simple way to do this...
var dt = Convert.ToDateTime(Convert.ToDateTime("09/01/2015 00:00:00").ToString("yyyy-MM-ddThh:mm:ssZ"))
I thought this would be a really simple, and i've tried to google it and I keep getting the exception String was not recognized as a valid DateTime.
This is my value "2013-10-21T14:10:49" this is what I want to convert it into 10/21/2013 10:49
string sample = "2013-10-21T14:10:49";
DateTime date31 = DateTime.ParseExact(sample, "MM/dd/yyyy HH:mm", System.Globalization.CultureInfo.InvariantCulture);
When you write DateTime.ParseExact(sample, "MM/dd/yyyy HH:mm", ...), you are saying that sample is in the format MM/dd/yyyy HH:mm. Since it is not, it throws an exception.
It's important to know that a DateTime does not have any format associated with it. It's only when you convert it to or from a string that format can come into play. You should probably use something like this:
string sample = "2013-10-21T14:10:49";
DateTime date31 = DateTime.Parse(sample, System.Globalization.CultureInfo.InvariantCulture);
string date31string = date31.ToString("MM/dd/yyyy HH:mm", System.Globalization.CultureInfo.InvariantCulture);
// date31string is "10/21/2013 14:10"
Instead of ParseExact, I used Parse, since the format is recognized by Parse, and I don't see much point in limiting what sort of formats it can accept to only that particular format.
Your string appears to be in format of "Xml-serialized". So it is the job of XmlConvert.
string sample = "2013-10-21T14:10:49";
string converted = XmlConvert.ToDateTime(sample, XmlDateTimeSerializationMode.Unspecified)
.ToString("MM/dd/yyyy HH:mm", CultureInfo.InvariantCulture);
You don't need the ParseExact method, the Parse method is sufficient because it allows your date representation. See DateTime - The string to parse for an overview of allowed input formats.
This means the following works:
string sample = "2013-10-21T14:10:49";
DateTime parsed = DateTime.Parse(sample);
Console.WriteLine(parsed.ToString("MM/dd/yyyy HH:mm:ss"));
And the result is:
10/21/2013 14:10:49
string dt = "10/25/2010 11:40:05 PM";
var currentThread = Thread.CurrentThread.CurrentCulture; //ru-RU
DateTime dateTime = DateTime.Parse(dt); //Exception!
How to parse that dt?
UPDATE:
In my case DateTime can be represent as "25.10.2010 11:40:05" or "10/25/2010 11:40:05 PM"
Is these any "generic" method to parse it without changing CurrentCulture?
Use a custom Date and Time format string, using either ParseExact or TryParseExact.
DateTime dateTime;
DateTime.TryParseExact(
dt,
"MM/dd/yyyy hh:mm:ss tt",
CultureInfo.InvariantCulture,
DateTimeStyles.None,
out dateTime
);
The string cannot be parsed as a Russian DateTime representation since the Russian culture doesn't use AM/PM, hence the use of the use of CultureInfo.InvariantCulture which is a US like culture (it represents no specific culture, but is modeled after the en-US one).
Try using ParseExact instead:
DateTime myDate = DateTime.ParseExact("10/25/2010 11:40:05 PM", "MM/dd/yyyy hh:mm:ss tt", CultureInfo.InvariantCulture);
Try DateTime.Parse(dt, CultureInfo.GetCultureInfo("EN-us"))
var result = DateTime.ParseExact(dt,
"MM/dd/yyyy hh:mm:ss tt",
CultureInfo.InvariantCulture);
To avoid runtime exceptions use safe DateTime.TryParseExact() method, it returns false in case of unsuccessfull parsing rather than throwing the FormatException exception
Russia doesn't use AM and PM as their AM/PM designators, which is at least one reason that would fail. Another is that Russia may not use the "month/day/year" format which is mostly a peculiarity of the US as far as I'm aware. (I can't remember Russia's format strings offhand; I do remember that the genitive month names caused me grief recently, but that's another story...)
I would personally explicitly specify the culture as the invariant culture, and also explicitly specify the format string:
string text = "10/25/2010 11:40:05 PM";
string pattern = "MM/dd/yyyy hh:mm:ss tt";
DateTime dt = DateTime.ParseExact(text, pattern,
CultureInfo.InvariantCulture);
If this might reasonably be expected to fail, you should use DateTime.TryParseExact instead, to handle failure gracefully without involving exceptions.
Try something like this:
dateTime = DateTime.Parse(dt, CultureInfo.CreateSpecificCulture("en-US"));
I want to convert text to datetime but having error.My text box value is in format dd/MM/yyyy
String was not recognized as a valid DateTime.
myFtMaster.GENTRTYDATEFROM =Convert.ToDateTime(txtTreatyPeriodfrom.Text.ToString());
My business object 'gentrtydatefrom' datatype is DateTime. Also what is the best way to avoid these type of errors without using a Try catch block.
You either specify a culture that uses that specific format:
myFtMaster.GENTRTYDATEFROM = Convert.ToDateTime(
txtTreatyPeriodfrom.Text, CultureInfo.GetCulture("en-GB")
);
or use the ParseExact method:
myFtMaster.GENTRTYDATEFROM = DateTime.ParseExact(
txtTreatyPeriodfrom.Text, "dd/MM/yyyy", CultureInfo.Invariant
);
The ParseExact method only accepts that specific format, while the Convert.ToDateTime method still allows some variations on the format, and also accepts some other date formats.
To catch illegal input, you can use the TryParseExact method:
DateTime d;
if (DateTime.TryParseExact(txtTreatyPeriodfrom.Text, "dd/MM/yyyy", CultureInfo.Invariant, DateTimeStyles.None, out d)) {
myFtMaster.GENTRTYDATEFROM = d;
} else {
// communcate the failure to the user
}
Use something like the following instead:
DateTime date = DateTime.MinValue;
DateTime.TryParse(txtTreatyPeriodfrom.Text, out date);
TryParse is similar to DateTime.Parse() but it does not throw an exception if the conversion fails.
If you want to use the en-CA specific culture use the following:
DateTime.TryParse(txtTreatyPeriodfrom.Text, new CultureInfo("en-CA"),
DateTimeStyles.AllowWhiteSpaces, out date);
Then obviously deal with those dates that fail to parse.
Ensuring the user is prompted on the format will obviously reduce mistakes.
Have a look at
DateTime.TryParse(String value, out DateTime, [culture settings])