I get the user machine's date pattern using this:
Dim sysFormat As String = CultureInfo.CurrentCulture.DateTimeFormat.ShortDatePattern
so for example it comes as M/d/yy but in my program I want to parse them in a M/d/yyyy format. But they could even have some other format, we don't know what format. It is ALWAYS gonna be US English tho.
So is there a way to automatically convert whatever it is to the M/d/yyyy format ? or do I have to manually do some string processing code and split the string to different parts for day,month, year?
Have you tried formatting your String to a Datetime object and then parsing using a specific formatter?
Dim myDate As DateTime = DateTime.ParseExact(sysFormat, "M/d/yyyy",
System.Globalization.CultureInfo.InvariantCulture)
And your new String (the one that's formatted) is:
Dim formattedStringDate As String = myDate.ToString("M/d/yyyy")
The requirements you have seem quite specific. You could use DateTime.TryParseExact to try parsing a few valid formats and check whether any results in a valid date. With new C# features you could even get rid of the extra out-parameter declaration. For example:
DateTime.TryParseExact(dateTime,
"M/d/yy",
CultureInfo.InvariantCulture,
DateTimeStyles.None,
DateTime out dt);
Related
I'm trying to format a date for an API. the desired format is: yyyy-MM-ddTHH:mm:ss.fffffff+HH:mm
(eg. 2022-10-12T09:52:14.1234567+03:00). I'm using Date.ParseExact in the following way:
Date.ParseExact("2022-10-12T09:52:14.1234567+03:00", "yyyy-MM-ddTHH:mm:ss.fffffff+HH:mm", CultureInfo.InvariantCulture)
.
Initially I used 'Now' instead of this string, but then I saw that the string and the desired format have to match. The error I'm getting is 'DateTime pattern 'H' appears more than once with different values.'. Is there a way to avoid that? Also is it possible to use 'Now' in this line?
Thank you
I suspect that you don't have a parse issue, you don't need ParseExact at all. You have a Date and want to return it as a formatted string. Then use ToString and zzz for the utc-offset:
string result = DateTime.Now.ToString("yyyy-MM-ddTHH:mm:ss.fffffffzzz");
Read also: Custom date and time format strings
i am using the date.parse function to format the date input in the textbox.
However if I input a future date the date parse function fails.
Why is it so?
I need to format the date and also input future dates.
If IsDate(TransactionDate.Text) Then
TransactionDate.Text = Date.Parse(TransactionDate.Text)
Else
MsgBox("Enter correct Transaction date")
TransactionDate.Focus()
End If
i used 12/5/2013 and it worked fine.
I suspect it didn't, actually. I suspect it actually parsed it as December 5th 2013, when you meant May 12th 2013.
It seems that it's trying to parse it as a format of MM/dd/yyyy, whereas you mean dd/MM/yyyy.
That could be because the thread you're using is in a US culture, for example.
I suggest that you use DateTime.TryParseExact:
If you want to specify a precise format, you can do that using a custom date/time format pattern
If you want to allow .NET to use an appropriate format for the culture, you can do that using a standard date/time format pattern
Specify the culture you want to use for parsing, using CultureInfo.InvariantCulture if it's meant to parse machine-generated text. You can use null to mean "the culture of the currently executing thread" but personally I'd make that explicit, for readability
Use the return value to determine whether parsing failed. If this indicates a bug somewhere, then it would make sense to use DateTime.ParseExact instead, as that will throw an exception. Basically you need to work out what you want to do on error.
You need to specify the format you are expecting the data string to be in. Dates can be written in many formats - US (mm/dd/yyyy) or European (dd/mm/yyyy), two digit years (yy) or four digit years (yyyy), different separator (/) vs (-) and so on. The list is endless.
You either need to state explicitly what date you expect or write your code to try various formats and cope with incorrect inputs.
The danger with the latter approach is that dates can be ambiguous - is "1/2/2013" the 1st of February or the 2nd of January?
Use an overload of Date.TryParse that takes an IFormatProvider and report an error if it fails.
dateString = "2008-03-01 10:00"
culture = CultureInfo.CreateSpecificCulture("fr-FR")
styles = DateTimeStyles.AdjustToUniversal Or DateTimeStyles.AssumeLocal
If DateTime.TryParse(dateString, culture, styles, dateResult)
Console.WriteLine("{0} converted to {1} {2}.", _
dateString, dateResult, dateResult.Kind)
Else
Console.WriteLine("Unable to convert {0} to a date and time.", dateString)
End If
Use DateTime.ParseExact and pass the format and provide.
dateString = "13/05/2013";
format = "dd-MM-yyyy";
CultureInfo provider = CultureInfo.InvariantCulture;
var result = DateTime.ParseExact(dateString, format, provider);
I have spent quite a few hours and still unable to understand this:
Dim unix_time_at_midnight As Long
DateTime.DateFormat = "MM/dd/yyyy"
unix_time_at_midnight = DateTime.DateParse(DateTime.Date(unix_time*1000))/1000
where both unix_time_at_midnight and unix_time are long values. I understand DateTime.DateParse excepts a String and converts it to DateTime. What is (DateTime.Date(unix_time*1000))/1000 returning and what is its equivalent in Java? The requirement is to get the number of seconds since GMT midnight and I have successfully implemented it in Java. However, I would like to understand this particular line of code written in VB.net
EDIT: This method was written in Basic4Android and probably constitutes more of its libraries then vb.net. However, I have looked into each for details but unable to understand. Would appreciate if you could elaborate. Please see the links.
Take this:
DateTime.Date(unix_time*1000)
The documentation says:
Date (Ticks As Long) As String
Returns a string representation of the date (which is stored as ticks).
The date format can be set with the DateFormat keyword.
So that part returns a string representing the date.
It then uses DateTime.DateParse, which is documented as:
DateParse (Date As String) As Long
Parses the given date string and returns its ticks representation.
Taken together, this appears to take the ticks, multiplied by 1000, converted to a string that doesn't contain hour information which is parsed back to ticks which are divided by 1000.
The important thing to note is that the DateFormat set on the line before contains only the formatting for the date, no hours/minutes/seconds and smaller units of time exist in it. This means that the string returned essentially represents midnight of that date.
I am using these codes for displaying time in VB.NET
it shows up in 24 hours format besides i need it in 12 hours format
System.DateTime.Now.Hour
System.DateTime.Now.Minute
System.DateTime.Now.Second
example:
14:12:42
I need it as :
02:12:42
thanks.
Use String.Format. For example:
String.Format("{0:T}", System.DateTime.Now) //02:12:42 PM
String.Format("{0:hh:mm:ss}", System.DateTime.Now) //02:12:42
String.Format("{0:hh:mm:ss tt}", System.DateTime.Now) //02:12:42 PM
Also, this website to be very helpful in summarizing the various ways you can use String.Format. Keep in mind the culture can make a difference on non-custom formats. The first example above using T (Long Time format) works on my US-based PC just fine. But if you say:
String.Format(System.Globalization.CultureInfo.InvariantCulture, _
"{0:T}", System.DateTime.Now)
You end up with 14:12:42. The latter two examples are custom formats and are not affected by culture.
When using DateTime objects you can actually use the ToString() method and set your format inside it.
string currentTime = System.DateTime.Now.ToString("hh:mm:ss");
Check this msdn article out for more clarity:
http://msdn.microsoft.com/en-us/library/zdtaw1bw.aspx
Use the appropriate format string for display.
string formatted = myDateTime.ToString("hh:mm:ss");
I have used a custom format string in this case.
1-Use regex to get first two characters of that string ie from 23:11:59 get 23
2-convert this number to integer type
3-now check it if it is not greater than 12 and if it is subtract 12 from it and by using string.replace replace the old value.
Try This...
Dim CurTime As String
CurTime = TimeOfDay.ToString("h:mm:ss tt")
I'm facing problem while conversion of date
if I used -- Date.parse("28/01/2011")
it gives me error as
"String was not recognized as a valid DateTime."
so then I modify above code as -- CDate("28/01/2011")
it gives me error as
"Cast from string "28/01/2011" to type 'Date' is not valid."
I used convert.todatetime also date.parseexact but nothing is working...
I'm using VS2003 in asp.net1.1 with vb.net
Probably Parse is using InvariantCulture date format "MM/dd/yyyy". Maybe you can try with
DateTime.ParseExact("28/01/2011", "dd/MM/yyyy", CultureInfo.InvariantCulture)
or passing a correct culture on Parse, like spanish that has date format dd/MM/yyyy
Date.Parse("28/01/2011", new CultureInfo("es-ES", true));
Write from memory, maybe is not accurate