String comes back from the database with a format: '00/00/0000' I need to then compare it to a date that the user has entered in the same format. How do I make the conversion and compare the two dates?
Use the static ParseExact method on the DateTime structure to convert the string. You will also pass the format you want, either dd/MM/yyyy or MM/dd/yyyy depending on what format you want (the example of 00/00/0000 doesn't give any indication of what format applies for you).
You can use
Dim dateA = DateTime.ParseExact(firstDateString, #"dd\/MM\/yyyy", Null)
Dim dateB = DateTime.ParseExact(secondDateString, #"dd\/MM\/yyyy", Null)
Dim areEqual = (dateA = dateB);
Assuming that your date format is day/month/year.
If it's month/day/year just swap dd and MM
Try something like this:
String.Compare("00/00/0000", dateTime.ToString("MM/dd/yyyy"))
But perhaps a better approach would be to do this:
DateTime.Equals(yourDateTime, DateTime.Parse(databaseDateTime));
Try the following
Dim date1 = CDate(firstDateString)
Dim date2 = CDate(secondDateString)
Dim comp = date1 = date2
When you say compare, are you trying to analysis if the dates are the same (to the day) or within a period of a few days ? If to compare if the dates are the same then you can just compare the string or use the date.equals (as mentioned in posts before this one) , if you are trying to determine with a range you will have to use date compare
Dim lDate1 As String = "29/03/2009"
Dim lDate2 As String = "30/03/2009"
Dim lPeriod As Int16 = 7
If lDate1 = lDate2 Then
'** Dates the same
End If
If Date.Equals(Date.ParseExact(lDate1, "dd/MM/yyyy", Nothing), Date.ParseExact(lDate2, "dd/MM/yyyy", Nothing)) Then
'** The same
End If
If Date.Compare(Date.ParseExact(lDate1, "dd/MM/yyyy", Nothing), Date.ParseExact(lDate2, "dd/MM/yyyy", Nothing)) > (lPeriod * -1) And Date.Compare(Date.ParseExact(lDate1, "dd/MM/yyyy", Nothing), Date.ParseExact(lDate2, "dd/MM/yyyy", Nothing)) < lPeriod Then
'** Within the period
End If
Related
I'm trying to figure out how best to handle different date formats that I might have as input.
The specific case is about the dates dd/MM/yyyy and MM/dd/yyyy.
At the time I try to convert the date as below:
firstDate = CDate("10/22/1988")
It obviously returns an error, how can I handle both cases in a generic way?
You can use Date.TryParseExact with the allowed format patterns:
Dim patterns As String() = {"dd/MM/yyyy", "MM/dd/yyyy"}
Dim dt As Date
Dim valid = Date.TryParseExact(str, patterns, CultureInfo.InvariantCulture, DateTimeStyles.None, dt)
Here a full working demo:
Sub Main
Dim inputs As String() = {"10/22/1988", "22/10/1988"}
Dim patterns As String() = {"dd/MM/yyyy", "MM/dd/yyyy"}
For Each str As String In inputs
Dim dt As Date
Dim valid = Date.TryParseExact(str, patterns, CultureInfo.InvariantCulture, DateTimeStyles.None, dt)
Console.WriteLine($"Valid: {valid} Date-Value: {dt}")
Next
End Sub
Output(i'm in germany):
Valid: True Date-Value: 22.10.1988 00:00:00
Valid: True Date-Value: 22.10.1988 00:00:00
In case of input like "3/5/1988" you should also allow:
"M/d/yyyy", "d/M/yyyy"
In this case the order is also the priority, so if both could work, the first wins.
I've been doing this, is it possible to get the middle string in datetime.
Example :
Basically my string return this '12/23/2015 12:00:00 AM'.
However, what i want is actually '15' from the year 2015.
I've been using something like this 'strDate = strDate.Substring(0, 9)',
which sometimes return me wrong when the date is something like this '1/2/2015 12:00:00 AM'
Can someone help me on this, i am not sure if we can get the middle.
Don't use string methods for this, use DateTime.TryParseExact:
Dim str = "12/23/2015 12:00:00 AM"
Dim dt As DateTime
If DateTime.TryParseExact(str, "MM'/'dd'/'yyyy hh:mm:ss tt", Globalization.CultureInfo.InvariantCulture, Globalization.DateTimeStyles.None, dt) Then
Dim yearOnly As String = dt.ToString("yy") ' 15
End If
Update: with CultureInfo.InvariantCulture and this format you don't even need to use TryParseExact, you can use Parse/TryParse immediately:
DateTime.TryParse(str, CultureInfo.InvariantCulture, DateTimeStyles.None, dt)
MSDN: Custom Date and Time Format Strings, The "yy" Custom Format Specifier
If you really want to treat it as just strings, you can get it by splitting twice. First on the space, then on the slashes:
Dim justDate as String = strDate.Split(" ")(0) 'contains "12/23/2015"
Dim justYear as String = justDate.Split("/")(2) 'contains "2015"
Dim partYear as String = justYear.Substring(2,2) 'contains "15"
or all in one line:
Dim partYear as String = strDate.Split(" ")(0).Split("/")(2).Substring(2,2)
Try this
dim dateStr as string
dateStr = "12/23/2015 12:00:00 AM"
dim dateobj as new DateTime
dateobj = DateTime.Parse(dateStr)
dim year as integer
year = dateobj.Year
dim youWantStr = year.ToString().Substring(2)
Console.WriteLine(youWantStr)
I just want to ask how VB.NET perform is conversion of date from string. I am currently designing a database view and convert the date into MMddyyyy format, but I am worried that CDATE it will read it as ddMMyyyy.
I want it to make it shorter and converting the date using CDATE instead of using the traditional M/d/yyyy h:mm:ss tt.
Example:
Dim myDate As Date = CDate(DataTable.Rows(0).Item("DateValue").ToString())
CDate depends on the control panel regional settings and is not recommended - you should use Date.ParseExact instead
Const MyDateFormat As String = "MMddyyyy"
Dim dte As Date = #2/1/2003#
'convert the date to a string
Dim strDate As String = dte.ToString(MyDateFormat)
'convert the string back to a date
Dim dte2 As Date = Date.ParseExact(strDate, MyDateFormat, System.Globalization.CultureInfo.InvariantCulture)
If dte = dte2 Then
MsgBox("They're the same :-) " & strDate)
Else
MsgBox("They're different :-(")
End If
For your code, it would look like:
Dim myDate As Date = Date.ParseExact(DataTable.Rows(0).Item("DateValue").ToString(), "MMddyyyy", System.Globalization.CultureInfo.InvariantCulture)
I want to manipulate my String data for example I have a x="20140118"
to y="01/18/2014" how can I do it? I need it for the value in DateTimePicker on VB.NET.
Thanks
DateTimePicker.Value wants a DateTime not a string. So you need to parse it:
Dim dt As DateTime = DateTime.ParseExact("20140118", "yyyyMMdd", CultureInfo.InvariantCulture)
dateTimePicker1.Value = dt
DateTime.ParseExact
Custom Date and Time Format Strings
However, just for the sake of completeness, if you need a string 01/18/2014 from the DateTime you can use DateTime.ToString:
Dim date As String = dt.ToString("MM/dd/yyyy", CultureInfo.InvariantCulture)
If that is your local date format you could also use these more concise approaches:
)
Dim date As String = dt.ToShortDateString()
)
Dim date As String = dt.ToString("d")
I am developing asp.net site using vb framework 3.5.
Im having difficulties converting string data into Date
I tried using cdate function,
I have a variable sdate which is a string variable and date is stored in it which comes from textbox as dd/mm/yyyy now i want to convert this string into a Date variable as i need to perform the operations as Add a day or Subtract a day.
Please guide me how to go about this. i get the error on 3rd line as,String was not recognized as a valid DateTime. I have tried to do as follows but the error comes
Dim sdate As String
Dim expenddt As Date
expenddt = Date.Parse(edate)
expenddt = expenddt.AddDays(-1)
But i get the error as
Conversion from String to type Date is not valid.
How can I get a Date from the string?
You should have to use Date.ParseExact or Date.TryParseExact with correct format string.
Dim edate = "10/12/2009"
Dim expenddt As Date = Date.ParseExact(edate, "dd/MM/yyyy",
System.Globalization.DateTimeFormatInfo.InvariantInfo)
OR
Dim format() = {"dd/MM/yyyy", "d/M/yyyy", "dd-MM-yyyy"}
Dim expenddt As Date = Date.ParseExact(edate, format,
System.Globalization.DateTimeFormatInfo.InvariantInfo,
Globalization.DateTimeStyles.None)
OR
Dim format() = {"dd/MM/yyyy", "d/M/yyyy", "dd-MM-yyyy"}
Dim expenddt As Date
Date.TryParseExact(edate, format,
System.Globalization.DateTimeFormatInfo.InvariantInfo,
Globalization.DateTimeStyles.None, expenddt)
Nobody mentioned this, but in some cases the other method fails to recognize the datetime...
You can try this instead, which will convert the specified string representation of a date and time to an equivalent date and time value
string iDate = "05/05/2005";
DateTime oDate = Convert.ToDateTime(iDate);
MessageBox.Show(oDate.Day + " " + oDate.Month + " " + oDate.Year );
Try to see if the following code helps you:
Dim iDate As String = "05/05/2005"
Dim oDate As DateTime = Convert.ToDateTime(iDate)
Try converting date like this:
Dim expenddt as Date = Date.ParseExact(edate, "dd/mm/yyyy",
System.Globalization.DateTimeFormatInfo.InvariantInfo);
Hope this helps.
Try to use DateTime.ParseExact method, in which you can specify both of datetime mask and original parsed string.
You can read about it here: MSDN: DateTime.ParseExact