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How to parse datetime returns from ToString

When I use the following datetime format in the Windows calendar settings.
Short date: M/d
Long time: H:mm:ss
The following code can't work.
var s = DateTime.Now.ToString(); // 4/28 8:00:00
var b = DateTime.TryParse(s, out dt); // false
The string is returned from a library, so I cannot change it, is it possible to write a parsing method that works for any kind of datetime format in the Windows calendar settings?
Update, from #MathiasR.Jessen's suggestion, I have found a solution, but it is not elegant because I have to concatenate the format string manually.
var dtf = CultureInfo.CurrentCulture.DateTimeFormat;
var fmt = dtf.ShortDatePattern + " " + dtf.LongTimePattern;
var b = DateTime.TryParseExact(s, fmt, null, DateTimeStyles.None, out dt);
Now the question changes to is there a better way?

Note that DateTime.TryParse() or DateTime.Parse() will not understand just any custom format. For custom datetime formats you need to use DateTime.TryParseExact() and DateTime.ParseExact():
Here is a demo Demo with that would be able to parse your input string.

You can Use "DatetTime.Now.ToString("yyyy-MM-dd")" it returns the value in year-shortMonth-date.
You can change the format according to your code.

Convert 12 hour time to Timespan C#

Using ASP.NET Forms, I'm encountering a problem with converting a 12 hour time into a timespan. Below I'm combining DateTime with TimeSpan as the user chooses a date and then a time. The fields are controlled by javascript.
DateTime DateResult = DateTime.TryParse(txtDate.Text, out DateResult) ? DateResult : DateTime.Today;
TimeSpan TimeResult = TimeSpan.TryParseExact(txtTime.Text, "h:mm tt", CultureInfo.InvariantCulture, out TimeResult) ? TimeResult : new TimeSpan();
DateResult = DateResult.Add(TimeResult)
So parsing the date works fine, but Timespan doesn't. One example:
Date Entered: 08/03/2018
Time Entered: 3:00 AM
Values are gettined passed okay but time fails so DateResult becomes "08/03/2018 00:00" but not "08/03/2018 03:00". I have also tried using the method TimeSpan.TryParse but no luck with that one.
I've also made sure that the format is correct by manually entering the time in the database behind the scenes. The gridview has a column that shows the full date in this format "dd/MM/yyyy h:mm tt", and works.
Anyone please share some light? Ideally, I would like to avoid any third party plug-ins.

Parse them together
Simplest thing is to just concatenate the strings before parsing as a single DateTime, e.g.
var dateEntered = #"08/03/2018";
var timeEntered = #"3:00 am";
DateTime result;
var completeDateString = dateEntered + " " + timeEntered;
var ok = DateTime.TryParse(completeDateString, out result);
if (!ok) result = DateTime.Today;
Console.WriteLine(result);
Output:
8/3/2018 3:00:00 AM
Ta da
If you have to parse them separately
If you'd like to work with the fields separately, you still can (I guess you'd have to do this if you want the time format to be exact but the date portion to be flexible, as it is in your example). But TimeSpan.TryParseExact is really different from DateTime.Parse. The format codes are different; it doesn't support the ":" character (except as a literal with an escape, e.g. "\:"), for example, or the "tt" formatting specifier. I'm guessing the concept of am/pm has to do with an absolute point in time, not a relative time offset, so isn't provided for. But you can still parse the textbox as a DateTime and use its time portion.
You can probably shorten this a bit but this example gives you everything you need:
static public DateTime ParseDateTime(string input)
{
DateTime output;
var ok = DateTime.TryParse(input, out output);
if (ok) return output;
return DateTime.Today;
}
static public TimeSpan ParseTime(string input)
{
DateTime output;
var ok = DateTime.TryParseExact(input, #"h:mm tt", CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.NoCurrentDateDefault, out output);
return output.Subtract(output.Date);
}
public static void Main()
{
var dateEntered = #"08/03/2018";
var timeEntered = #"3:00 am";
DateTime dateResult = ParseDateTime(dateEntered);
TimeSpan timeResult = ParseTime(timeEntered);
DateTime finalResult = dateResult.Add(timeResult);
Console.WriteLine(finalResult);
}
Output:
8/3/2018 3:00:00 AM
Code on DotNetFiddle

See ParseExact or https://msdn.microsoft.com/en-us/library/system.timespan.tryparseexact(v=vs.110).aspx for TryParseExact should work for both DateTime as well as TimeSpan inter alia
Fyi it's called the meridian and see also AM/PM to TimeSpan

Parsing non standard date strings in C#

How would you handle the following string value that needs to be converted to a DateTime object?
"2015/01/22 12:08:51 (GMT+09:00)"
Would like to include this as a recognized DateTime pattern. As I encounter other formats, I would like to just implement a new pattern.

Here a piece of code that will successfully parse the given string (notice DateTimeOffset rather than DateTime):
var str = "2015/01/22 12:08:51 (GMT+09:00)";
var dt = DateTimeOffset.ParseExact
(str,
"yyyy/MM/dd HH:mm:ss (\\G\\M\\TK)",
System.Globalization.CultureInfo.InvariantCulture
);
//dt now has +9:00 offset - that's correct only if GMT is provided as UTC.
More info at The Difference Between GMT and UTC

This code takes a string and converts it into a DateTime object
DateTime myDate = DateTime.Parse("2017-08-28 14:20:52,001", "yyyy-MM-dd HH:mm:ss,fff", System.Globalization.CultureInfo.InvariantCulture);
All you need to do is create a format that matches your input. This link helps:
https://learn.microsoft.com/en-us/dotnet/standard/base-types/custom-date-and-time-format-strings
For more details read this: https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/strings/how-to-convert-a-string-to-a-datetime

Here there is the official documentation of DateTime.Parse with some examples. It covers also the case of other formats
https://msdn.microsoft.com/it-it/library/system.datetime.parse(v=vs.110).aspx

Using DateTime.ParseExact is probably your best bet. It takes in an input string and an expected format string that the input should match. It will return true if the conversion was successful, and the out parameter will be the result of the conversion (result in the example below).
I was unable to get it to work without forcibly removing the "GMT" portion, but if that's acceptable to you, the code below should work.
This example takes the original input and converts it to UTC time (i.e. it adjusts the time based on your GMT value, which is to subtract 9 hours in your example):
var input = "2015/01/22 12:08:51 (GMT-08:00)";
var format = "yyyy/MM/dd H:mm:ss (zzz)";
DateTime result;
// Remove the "GMT" portion of the input
input = input.Replace("GMT", "");
if (DateTime.TryParseExact(input, format, CultureInfo.InvariantCulture,
DateTimeStyles.AdjustToUniversal, out result))
{
Console.WriteLine($"'{input}' converts to {result} UTC time.");
}
else
{
Console.WriteLine($"'{input}' is not in the correct format.");
}
This example is modified from the ones on the DateTime.TryParseExact documentation.

Formatting datetime variable [closed]

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I am trying to convert and store a date in the form of String into datetime variable.
String fromdate= "02-JUN-2014";
DateTime dFromDate = Convert.ToDateTime(fromdate);
This dfromDate is used in another function which expects date to be in 02-JUN-2014 format.But since dfromDate storing the date as 06/02/2014, there is a format exception.

You can use ParseExact()
String fromdate="02-JUN-2014";
DateTime dFromDate = DateTime.ParseExact(fromdate, "dd-MMM-yyyy",CultureInfo.InvariantCulture)

Wrap fromDate in quotes:
var fromdate = "02-JUN-2014";
var dFromDate = Convert.ToDateTime(fromdate);

I am not to sure of the entire context but you could always use the folowing to create a new date:
DateTime thisDate1 = new DateTime(2011, 6, 10);
Console.WriteLine("Today is " + thisDate1.ToString("MMMM dd, yyyy") + ".");
// The example displays the following output:
// Today is June 10, 2011.

You want to use DateTime.ParseExact i.e.
DateTime dFromDate = DateTime.ParseExact(fromdate, "dd-MMM-yyyy", CultureInfo.InvariantCulture);
You may need to specific a culture for your language if you are not US (CultureInfo.InvariantCulture is a special form of US).

Convert.ToDateTime uses standard date and time format of your CurrentCulture and looks like dd-MMM-yyyy is not one of them.
You can use ParseExact method with english-based culture like InvariantCulture.
String fromdate = "02-JUN-2014";
DateTime dFromDate = DateTime.ParseExact(fromdate, "dd-MMM-yyyy",
CultureInfo.InvariantCulture);

Using DateTime.ParseExactmight work, and itis the best option if you know exactly the format string, but you could also set the current CultureInfo for the call:
String fromdate= "02-JUN-2014";
DateTime dFromDate = Convert.ToDateTime(fromdate, CultureInfo.CurrentCulture);
Or:
String fromdate= "02-JUN-2014";
DateTime dFromDate = Convert.ToDateTime(fromdate, new CultureInfo("es-ES"));

String fromdate= "02-JUN-2014";
DateTime dFromDate = DateTime.ParseExact(fromdate,"dd-MMM-yyyy",
CultureInfo.InvariantCulture);
Use ParseExact method.

Your first problem might be, that you need to assign a string like this:
String fromdate = "02-JUN-2014";

How to validate if a "date and time" string only has a time?

I have a single string variable that stores what could be a full date or a partial date:
1) Full Date: 12/12/2010 12:33 AM
2) Partial Date: 12:33 AM (no date field only time)
I'm trying to figure out what would be the best approach to parse the string to figure out if the string is missing the date string or not. The reason is, in my code if the date is missing I will append a default date to the string (such as 1/1/1900). Keep in mind that the time could be in various formats.
Update - My particular answer to this problem.
As all the "posts" have stated, there are multiple answers to this problem, this is ultimately what I used and hope it can help others*:
public DateTime ProcessDateAndTime(string dateString)
{
string dateAndTimeString = dateString;
string[] timeFormats = new string[]
{
"hh:mm tt", "hh:mm:ss tt",
"h:mm tt", "h:mm:ss tt",
"HH:mm:ss", "HH:mm", "H:mm"
};
// check to see if the date string has a time only
DateTime dateTimeTemp;
if (DateTime.TryParseExact(dateString, timeFormats,
CultureInfo.InvariantCulture.DateTimeFormat, DateTimeStyles.None, out dateTimeTemp))
{
// setting date to 01/01/1900
dateAndTimeString = new DateTime(1900, 1, 1).ToShortDateString() + " " + dateString;
}
return DateTime.Parse(dateAndTimeString);
}
*Note: This method is based on the assumption that there are only a specific amount of time formats used in your application, and that it is guaranteed that a properly formatted date and time, or time only string passed in (pre-validation for removal of garbage text).

Use
Convert.ToDateTime(string value, IFormatProviderProvider provider)
Since the string comes in different flavors, provide different format providers as needed.
The order could be:
DateOnly
Time Only
DateTime
The convert will throw an format exception if it fails. If you prefer not to have exceptions, use Datetime.TryParse instead as that returns a boolean.
Depending on how the string is represented you could have more than 3 format providers.

You can try to validate string with a RegEx,
BTW, good regexes for DateTime validation can be found here

Here's one way to do this without knowing all possible time formats:
CultureInfo provider = CultureInfo.CurrentCulture;
DateTime time;
DateTime datetime;
bool isTime = DateTime.TryParse(dateString, provider, DateTimeStyles.NoCurrentDateDefault, out time)
&& time.Date == DateTime.MinValue.Date
&& DateTime.TryParse(dateString, provider, DateTimeStyles.None, out datetime)
&& datetime.Date != DateTime.MinValue.Date);
If the string only has a time then the first TryParse will set the date part to 1/1/0001 or DateTime.MinValue.Date and the second TryParse will set the date part to the current date. This will work unless it is run by Doctor Who after travelling back in time to 1/1/0001.

You can use DateTime.TryParseExact.

This might not be the best but it answers your question:
string dateString = "9:53AM";
if (!dateString.Contains('/')))
{
dateString = DateTime.Now.ToShortDateString() + " " + dateString;
}

Looking at the length of the string will be straight-forward and will support multiple formats. A string with a date and time will most certainly be longer than a string with just a time. However, if your input may have times with high precision (12:30:30:50:20 vs 12/11/11 12:30) and low precision this won't work.
This solution is ideal if you don't need to know the value in the string immediately, and only want to add the default date.
If you support times to the second, for instance, a time will have 8 or less characters and a date-time will have 9 or more.

Given that the time can be in various formats (12/24?) it would be best to user several patterns, in some pre-defined order, trying to parse with each and resolving when the first succeeds.

You can also try
DateTime aTime;
if (DateTime.TryParse(dateString, CultureInfo.InvariantCulture.DateTimeFormat, DateTimeStyles.NoCurrentDateDefault, out aTime))
{
//if the there is no date part in the dateString, date will
// default to Gregorian 1/1/0001
}