Binaryworld - Language features - DateTime and TimeSpan Objects ... [ VB.net -> Language ]

In this article we will explore some key language features which are frequently used by VB programmers.

DateTimes in VB.net

VB.net provides many new features for DateTime datatype. Unlike VB6 in VB.net you can initialize DateTime variable with verity of initial values. In VB.net you can initialize your datetime variable with 7 different ways. For example,

Click here to copy the following block

Dim mydate as New DateTime(2005,12,31) '//Becomes December 31, 2005
Dim mydate as New DateTime(2005,12,31,23,59,59) '//Becomes December 31, 2005 11:59:59 PM

'Or

Dim myDate as DateTime
mydate="12/31/2005 11:59:59 PM"

DateTime Shared Members

The shared DateTime properties:

Now : The current date and time as set on your system. Similar to the Visual Basic 6 function of the same name.
Today : The current date as set on your system.
UtcNow : The current date and time as set on your system, expressed as coordinated universal time (UTC), also known as Greenwich Mean Time.
MinValue : The smallest possible value a DateTime can have.
MaxValue : The largest possible value a DateTime can have.

DateTime Shared methods:

DaysInMonth : Given a year and month, returns the number of days in that month.
FromOADate : Returns a DateTime value that corresponds to the provided Ole Automation Date, which is a floating-point number representing the number of days from midnight, December 30, 1899. Use this method to convert dates stored in Microsoft Excel—for example, to .NET DateTime format.
IsLeapYear : Given a four-digit year, returns True if it is a leap year and False otherwise.

DateTime Properties:

In addition to shared members, DateTime datatype offers instance specific methods and properties. Here is the list of properties which are instance specific

Date : The date that dt contains.
Day : An integer between 1 and 31, representing the dt day of the month.
DayOfWeek : An enumerated constant that indicates the day of the week in the dt date, ranging from Sunday to Saturday.
DayOfYear : An integer between 1 and 366, representing the dt day of the year.
Hour : An integer between 0 and 23, representing the dt hour of day.
Millisecond : An integer between 0 and 999, representing the millisecond of the dt time.
Minute : An integer between 0 and 59, representing the minute of the dt time.
Month : An integer between 1 and 12, representing the dt month of the year.
Second : An integer between 0 and 59, representing the second of the dt time.
Ticks : A Long containing the number of Ticks in the dt date and time, counting from 12:00 A.M., January 1, 0001. A Tick is a 100-nanosecond period of time.
TimeOfDay : A TimeSpan that represents the fraction of the day between midnight and the dt time.
Year : An integer that represents dt year, between 1 and 9999.

DateTime Methods:

In the previous version of VB6 we used to have various APIs to for different time conversions but now no more APIs. DateTime offers rich set of conversion functions which you can use for most of the time.

ToFileTime : A system file time is a Long representing a date and time as 100-nanosecond intervals since January 1, 1601, 12:00 A.M.
ToLocalTime : Assumes that the parameter passed to it represents UTC time, and returns a DateTime, converted to local time, allowing for daylight savings time. The opposite of ToUniversalTime.
ToLongDateString : If the current culture is us-EN, returns a String with the date in the form: Monday, November 15, 2004. The format of the string varies depending on the current culture.
ToLongTimeString : If the current culture is us-EN, returns a String with the time in the form: 5:03:29 PM. The format of the string varies depending on the current culture.
ToOADate : Converts a DateTime to its OLE Automation date equivalent.
ToShortDateString : If the current culture is us-EN, returns a String with the date in the form: 11/15/2004. The format of the string varies depending on the current culture.
ToShortTimeString : If the current culture is us-EN, returns a String with the time in the form: 5:03:29 PM. The format of the string varies depending on the current culture.
ToString : Presents the DateTime value as a string, with many formatting choices.
ToUniversalTime : Assumes that the parameter passed to it represents local time, and returns a DateTime, converted to UTC time. The opposite of ToLocalTime.
Parse : Converts the specified string representation of a date and time to its System.DateTime equivalent.
ParseExact : Converts the specified string representation of a date and time to its System.DateTime equivalent using the specified format and culture-specific format information. The format of the string representation must match the specified format exactly.

Date and Time Formatting

DateTime format strings are used to control the formatting produced when a date or time is represented as a string.

DateTime format strings fall into two categories: standard format strings and custom format strings. The custom format strings allow DateTime objects to be formatted for situations where the standard formatting strings are not useful.

Format Specifier	Name	Example	Output
d	Short date pattern	Console.WriteLine(String.Format("{0:d}", Now))	8/22/2005
D	Long date pattern	Console.WriteLine(String.Format("{0:D}", Now))	Monday, August 22, 2005
t	Short time pattern	Console.WriteLine(String.Format("{0:t}", Now))	11:20 PM
T	Long time pattern	Console.WriteLine(String.Format("{0:T}", Now))	11:20:55 PM
f	Full date/time pattern (short time)	Console.WriteLine(String.Format("{0:f}", Now))	Monday, August 22, 2005 11:20 PM
F	Full date/time pattern (long time)	Console.WriteLine(String.Format("{0:F}", Now))	Monday, August 22, 2005 11:20:55 PM
g	General date/time pattern (short time)	Console.WriteLine(String.Format("{0:g}", Now))	8/22/2005 11:20 PM
G	General date/time pattern (long time)	Console.WriteLine(String.Format("{0:G}", Now))	8/22/2005 11:20:55 PM
M or m	Month day pattern	Console.WriteLine(String.Format("{0:m}", Now))	August 22
R or r	RFC1123 pattern	Console.WriteLine(String.Format("{0:r}", Now))	Mon, 22 Aug 2005 23:20:55 GMT
s	Sortable date/time pattern; conforms to ISO 8601	Console.WriteLine(String.Format("{0:s}", Now))	2005-08-22T23:20:55
u	Universal sortable date/time pattern	Console.WriteLine(String.Format("{0:u}", Now))	2005-08-22 23:20:55Z
U	Universal sortable date/time pattern	Console.WriteLine(String.Format("{0:U}", Now))	Tuesday, August 23, 2005 3:20:55 AM
Y or y	Year month pattern	Console.WriteLine(String.Format("{0:y}", Now))	August, 2005
Any other single character	Unknown specifier	Console.WriteLine(String.Format("{0:L}", Now))	System.FormatException

Custom DateTime Format Strings

The following table illustrates the output created by applying some custom DateTime format strings to a particular date and time.

Format Specifier	Description	Example (Date: Aug 9, 2005)	Output
d, dd	Day	Console.WriteLine(String.Format("{0:dd}", Now)) Console.WriteLine(String.Format("{0:M d}", Now)) Console.WriteLine(String.Format("{0:MMM dd}", Now))	10 8 10 Aug 10
ddd	Day name (Short)	Console.WriteLine(String.Format("{0:ddd}", Now)) Console.WriteLine(String.Format("{0:MMM ddd, yyyy}", Now))	Wed Aug Wed, 2005
dddd	Day name (Full)	Console.WriteLine(String.Format("{0:dddd}", Now)) Console.WriteLine(String.Format("{0:MMM dddd, yyyy}", Now))	Wednesday Aug Wednesday, 2005
f, ff, fff, ffff, ...	Second's fraction	Console.WriteLine(String.Format("{0:fff}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss.f}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss.ffff}", Now))	859 12:18:37.8 12:18:37.8593
g, gg, ggg, gggg, ...	Era	Console.WriteLine(String.Format("{0:gg}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss.fff g}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss.fff ggg}", Now))	A.D. 12:18:37.859 A.D. 12:18:37.859 A.D.
h , hh	Displays the hour for the specified DateTime in the range 1-12.	Console.WriteLine(String.Format("{0:hh}", Now)) Console.WriteLine(String.Format("{0:h:m:s}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss}", Now))	12 12:18:37 12:18:37
H, HH	Displays the hour for the specified DateTime in the range 0-23.	Console.WriteLine(String.Format("{0:HH}", Now)) Console.WriteLine(String.Format("{0:H:m:s}", Now)) Console.WriteLine(String.Format("{0:HH:mm:ss}", Now))	00 0:18:37 00:18:37
m, mm	Minutes	Console.WriteLine(String.Format("{0:mm}", Now)) Console.WriteLine(String.Format("{0:h:m:s}", Now)) Console.WriteLine(String.Format("{0:dd/MM/yyyy hh:mm:ss}", Now))	18 12:18:37 10/08/2005 12:18:37
M, MM	Month	Console.WriteLine(String.Format("{0:MM}", Now)) Console.WriteLine(String.Format("{0:d/M/yy}", Now)) Console.WriteLine(String.Format("{0:dd/MM/yyyy hh:mm:ss}", Now))	08 10/8/05 10/08/2005 12:18:37
MMM	Month name (Short)	Console.WriteLine(String.Format("{0:MMM}", Now)) Console.WriteLine(String.Format("{0:MMM, yyyy}", Now))	Aug Aug, 2005
MMMM	Month name (Full)	Console.WriteLine(String.Format("{0:MMMM}", Now)) Console.WriteLine(String.Format("{0:MMMM, yyyy}", Now))	August August, 2005
s, ss	Second	Console.WriteLine(String.Format("{0:ss}", Now)) Console.WriteLine(String.Format("{0:h:m:s}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss}", Now))	37 12:18:37 12:18:37
t, tt	AM or PM	Console.WriteLine(String.Format("{0:tt}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss t}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss tt}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss ttt}", Now))	AM 12:18:37 A 12:18:37 AM 12:18:37 AM
y, yy, yyyy	Year	Console.WriteLine(String.Format("{0:yy}", Now)) Console.WriteLine(String.Format("{0:MM, yy}", Now)) Console.WriteLine(String.Format("{0:MM, yyy}", Now))	05 08, 05 08, 2005
z, zz	Timezone offset (hours)	Console.WriteLine(String.Format("{0:zz}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss z}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss zz}", Now))	-04 12:18:37 -4 12:18:37 -04
zzz	Timezone offset (hours and minutes)	Console.WriteLine(String.Format("{0:zzz}", Now)) Console.WriteLine(String.Format("{0:hh:mm:ss G\MT zzz}", Now))	-04:00 12:18:37 GMT -04:00
'ABC' or "ABC"	Literal value	Console.WriteLine(String.Format("{0: 'Today is :' MMM, dd yyyy hh:mm:ss tt G\MT zzz}", Now))	Today is : Aug, 10 2005 12:18:37 AM GMT -04:00

Now lets look at the example which demonstrate varous DateTime methods and properties

Click here to copy the following block

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
  Console.WriteLine("".PadRight(50, "="))
  Console.WriteLine("DateTime Demo")
  Console.WriteLine("".PadRight(50, "="))
  DateTimeDemo()
  MsgBox("Check your output window (Clt + Alt + O)")
End Sub

Sub DateTimeDemo()
  '//Argument #0 , left aligned, width=40 char
  '//Argument #1 , left aligned, width=30 char
  Const OUT_FORMAT = "{0,-40} : {1,-30}"

  'Dim MyDate As New DateTime(2234322) '//ticks
  'Dim MyDate As New DateTime(2005, 2, 28) '//year,month,day
  'Dim MyDate As New DateTime(2005, 2, 28, 2, 11, 50) '//year,month,day,hour,min,sec

  Dim MyDate As New DateTime(2005, 2, 28, 2, 11, 50, 999) '//year,month,day,hour,min,sec,milisec
  Dim MyString As String

  '//DateTime Custom Formatting
  Console.WriteLine("'//DateTime Custom Formatting (" & MyDate.ToString("MM/dd/yyyy hh:mm:ss.fff tt zzz") & ")")
  DisplayDateTime(MyDate, "d - M - y")
  DisplayDateTime(MyDate, "dd - MM - yy")
  DisplayDateTime(MyDate, "ddd - MMM - yyy")
  DisplayDateTime(MyDate, "dddd - MMMM - yyyy")
  DisplayDateTime(MyDate, "MMM, dd yyyy h:m:s t")
  DisplayDateTime(MyDate, "MMM, dd yyyy hh:mm:ss tt")
  DisplayDateTime(MyDate, "MMM, dd yyyy hh:mm:ss.fff tt z")
  DisplayDateTime(MyDate, "MMM, dd yyyy hh:mm:ss.fff tt zz")
  DisplayDateTime(MyDate, "MMM, dd yyyy hh:mm:ss.fff tt zzz")
  DisplayDateTime(MyDate, "yyyy g")
  DisplayDateTime(MyDate, "yyyy gg")

  '//DateTime Instance Properties
  Console.WriteLine()
  Console.WriteLine("'//DateTime Instance Properties (" & MyDate.ToString & ")")
  Console.WriteLine(OUT_FORMAT, "MyDate.Date", MyDate.Date)
  Console.WriteLine(OUT_FORMAT, "MyDate.DayOfWeek", MyDate.DayOfWeek)
  Console.WriteLine(OUT_FORMAT, "MyDate.DayOfYear", MyDate.DayOfYear)
  Console.WriteLine(OUT_FORMAT, "MyDate.Day", MyDate.Day)
  Console.WriteLine(OUT_FORMAT, "MyDate.Month", MyDate.Month)
  Console.WriteLine(OUT_FORMAT, "MyDate.Hour", MyDate.Hour)
  Console.WriteLine(OUT_FORMAT, "MyDate.Minute", MyDate.Minute)
  Console.WriteLine(OUT_FORMAT, "MyDate.Second", MyDate.Second)
  Console.WriteLine(OUT_FORMAT, "MyDate.Millisecond", MyDate.Millisecond)
  Console.WriteLine(OUT_FORMAT, "MyDate.Ticks", MyDate.Ticks)
  Console.WriteLine(OUT_FORMAT, "MyDate.Ticks", MyDate.TimeOfDay)

  '//DateTime Shared Properties
  Console.WriteLine()
  Console.WriteLine("'//DateTime Shared Properties")
  Console.WriteLine(OUT_FORMAT, "MyDate.Today", MyDate.Today)
  Console.WriteLine(OUT_FORMAT, "MyDate.Now", MyDate.Now)
  Console.WriteLine(OUT_FORMAT, "MyDate.UtcNow", MyDate.UtcNow)
  Console.WriteLine(OUT_FORMAT, "MyDate.MinValue", MyDate.MinValue)
  Console.WriteLine(OUT_FORMAT, "MyDate.MaxValue", MyDate.MaxValue)

  '//DateTime Shared Methods
  Console.WriteLine()
  Console.WriteLine("'//DateTime Shared Methods")
  Console.WriteLine(OUT_FORMAT, "MyDate.DaysInMonth(2004, 2)", MyDate.DaysInMonth(2004, 2))
  Console.WriteLine(OUT_FORMAT, "MyDate.FromOADate(38568)", MyDate.FromOADate(38568))
  Console.WriteLine(OUT_FORMAT, "MyDate.IsLeapYear(2004)", MyDate.IsLeapYear(2004))

  '//DateTime Calculation Methods
  Console.WriteLine()
  Console.WriteLine("'//DateTime Methods (" & MyDate.ToString & ")")
  Console.WriteLine(OUT_FORMAT, "MyDate.ToString", MyDate.ToString)
  Console.WriteLine(OUT_FORMAT, "MyDate.Add(New TimeSpan(5, 0, 30))", MyDate.Add(New TimeSpan(5, 59, 30)))
  Console.WriteLine(OUT_FORMAT, "MyDate.AddDays(2)", MyDate.AddDays(2))
  Console.WriteLine(OUT_FORMAT, "MyDate.AddHours(5)", MyDate.AddHours(5))
  Console.WriteLine(OUT_FORMAT, "MyDate.AddMilliseconds(20000)", MyDate.AddMilliseconds(20000))
  Console.WriteLine(OUT_FORMAT, "MyDate.AddMinutes(7)", MyDate.AddMinutes(7))
  Console.WriteLine(OUT_FORMAT, "MyDate.AddMonths(2)", MyDate.AddMonths(2))
  Console.WriteLine(OUT_FORMAT, "MyDate.AddSeconds(3600)", MyDate.AddSeconds(3600))
  Console.WriteLine(OUT_FORMAT, "MyDate.AddTicks(100000)", MyDate.AddTicks(100000))

  '//DateTime Conversion Methods
  Console.WriteLine()
  Console.WriteLine("'//DateTime Methods (" & MyDate.ToString & ")")
  Console.WriteLine(OUT_FORMAT, "MyDate.ToFileTime", MyDate.ToFileTime)
  Console.WriteLine(OUT_FORMAT, "MyDate.ToFileTimeUtc", MyDate.ToFileTimeUtc)
  Console.WriteLine(OUT_FORMAT, "MyDate.ToLocalTime", MyDate.ToLocalTime)
  Console.WriteLine(OUT_FORMAT, "MyDate.ToLongDateString", MyDate.ToLongDateString)
  Console.WriteLine(OUT_FORMAT, "MyDate.ToLongTimeString", MyDate.ToLongTimeString)
  Console.WriteLine(OUT_FORMAT, "MyDate.ToOADate", MyDate.ToOADate)
  Console.WriteLine(OUT_FORMAT, "MyDate.ToShortDateString", MyDate.ToShortDateString)
  Console.WriteLine(OUT_FORMAT, "MyDate.ToShortTimeString", MyDate.ToShortTimeString)
  Console.WriteLine(OUT_FORMAT, "MyDate.ToString", MyDate.ToString)
  Console.WriteLine(OUT_FORMAT, "MyDate.ToUniversalTime", MyDate.ToUniversalTime)

  Dim sArr() As String, i As Integer
  sArr = MyDate.GetDateTimeFormats()
  For i = 0 To sArr.GetUpperBound(0)
    Console.WriteLine(OUT_FORMAT, "MyDate.GetDateTimeFormats()[Format#" & i & "]", sArr(i))
  Next
End Sub

Sub DisplayDateTime(ByVal dt As DateTime, ByVal strformat As String)
  '//Argument #0 , left aligned, width=40 char
  '//Argument #1 , left aligned, width=30 char
  Const OUT_FORMAT = "{0,-40} : {1,-30}"

  Dim MyString As String
  MyString = dt.ToString(strformat)
  Console.WriteLine(OUT_FORMAT, strformat, MyString)
End Sub

Output

==================================================
DateTime Demo
==================================================
'//DateTime Custom Formatting (02/28/2005 02:11:50.999 AM -05:00)
d - M - y                                : 28 - 2 - 5                    
dd - MM - yy                             : 28 - 02 - 05                  
ddd - MMM - yyy                          : Mon - Feb - 2005              
dddd - MMMM - yyyy                       : Monday - February - 2005      
MMM, dd yyyy h:m:s t                     : Feb, 28 2005 2:11:50 A        
MMM, dd yyyy hh:mm:ss tt                 : Feb, 28 2005 02:11:50 AM      
MMM, dd yyyy hh:mm:ss.fff tt z           : Feb, 28 2005 02:11:50.999 AM -5
MMM, dd yyyy hh:mm:ss.fff tt zz          : Feb, 28 2005 02:11:50.999 AM -05
MMM, dd yyyy hh:mm:ss.fff tt zzz         : Feb, 28 2005 02:11:50.999 AM -05:00
yyyy g                                   : 2005 A.D.                     
yyyy gg                                  : 2005 A.D.                     

'//DateTime Instance Properties (2/28/2005 2:11:50 AM)
MyDate.Date                              : 2/28/2005 12:00:00 AM         
MyDate.DayOfWeek                         : Monday                        
MyDate.DayOfYear                         : 59                            
MyDate.Day                               : 28                            
MyDate.Month                             : 2                             
MyDate.Hour                              : 2                             
MyDate.Minute                            : 11                            
MyDate.Second                            : 50                            
MyDate.Millisecond                       : 999                           
MyDate.Ticks                             : 632451535109990000            
MyDate.TimeOfDay                         : 02:11:50.9990000              

'//DateTime Shared Properties
MyDate.Today                             : 8/11/2005 12:00:00 AM         
MyDate.Now                               : 8/11/2005 11:35:41 AM         
MyDate.UtcNow                            : 8/11/2005 3:35:41 PM          
MyDate.MinValue                          : 1/1/0001 12:00:00 AM          
MyDate.MaxValue                          : 12/31/9999 11:59:59 PM        

'//DateTime Shared Methods
MyDate.DaysInMonth(2004, 2)              : 29                            
MyDate.FromOADate(38568)                 : 8/4/2005 12:00:00 AM          
MyDate.IsLeapYear(2004)                  : True                          

'//DateTime Methods (2/28/2005 2:11:50 AM)
MyDate.ToString                          : 2/28/2005 2:11:50 AM          
MyDate.Add(New TimeSpan(5, 59, 30))      : 2/28/2005 8:11:20 AM          
MyDate.AddDays(2)                        : 3/2/2005 2:11:50 AM           
MyDate.AddHours(5)                       : 2/28/2005 7:11:50 AM          
MyDate.AddMilliseconds(20000)            : 2/28/2005 2:12:10 AM          
MyDate.AddMinutes(7)                     : 2/28/2005 2:18:50 AM          
MyDate.AddMonths(2)                      : 4/28/2005 2:11:50 AM          
MyDate.AddSeconds(3600)                  : 2/28/2005 3:11:50 AM          
MyDate.AddTicks(100000)                  : 2/28/2005 2:11:51 AM          

'//DateTime Methods (2/28/2005 2:11:50 AM)
MyDate.ToFileTime                        : 127540483109990000            
MyDate.ToFileTimeUtc                     : 127540303109990000            
MyDate.ToLocalTime                       : 2/27/2005 9:11:50 PM          
MyDate.ToLongDateString                  : Monday, February 28, 2005     
MyDate.ToLongTimeString                  : 2:11:50 AM                    
MyDate.ToOADate                          : 38411.0915624884              
MyDate.ToShortDateString                 : 2/28/2005                     
MyDate.ToShortTimeString                 : 2:11 AM                       
MyDate.ToString                          : 2/28/2005 2:11:50 AM          
MyDate.ToUniversalTime                   : 2/28/2005 7:11:50 AM          
MyDate.GetDateTimeFormats()[Format#0]    : 2/28/2005                     
MyDate.GetDateTimeFormats()[Format#1]    : 2/28/05                       
MyDate.GetDateTimeFormats()[Format#2]    : 02/28/05                      
MyDate.GetDateTimeFormats()[Format#3]    : 02/28/2005                    
MyDate.GetDateTimeFormats()[Format#4]    : 05/02/28                      
MyDate.GetDateTimeFormats()[Format#5]    : 2005-02-28                    
MyDate.GetDateTimeFormats()[Format#6]    : 28-Feb-05                     
			...............
			
			...............
			
			...............

MyDate.GetDateTimeFormats()[Format#123]  : Monday, 28 February, 2005 7:11:50
MyDate.GetDateTimeFormats()[Format#124]  : Monday, 28 February, 2005 07:11:50
MyDate.GetDateTimeFormats()[Format#125]  : 28 February, 2005 7:11:50 AM  
MyDate.GetDateTimeFormats()[Format#126]  : 28 February, 2005 07:11:50 AM 
MyDate.GetDateTimeFormats()[Format#127]  : 28 February, 2005 7:11:50     
MyDate.GetDateTimeFormats()[Format#128]  : 28 February, 2005 07:11:50    
MyDate.GetDateTimeFormats()[Format#129]  : February, 2005                
MyDate.GetDateTimeFormats()[Format#130]  : February, 2005

Parse and ParseExact Methods

These 2 methods are very powerful and flexible if used with caution. Flexibility is always great but you have to pay the price of performance. Similar to the numeric types, the DateTime class has the capability to convert a string into a DateTime object. Both the Parse method and the ParseExact method can be used to convert a string representation of a date or time into a DateTime object. The Parse method converts any valid string representation, while the ParseExact method only converts strings that are of the form that you specify. Both methods can successfully convert any string that takes the form of one of the standard DateTime patterns described in the Date and Time Format Strings section.

Standard Datetime format string: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconstandarddatetimeformatstrings.asp

Custom formats : http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconcustomdatetimeformatstrings.asp

Lets look at the example

Click here to copy the following block

Sub ParseDateTimeDemo()
  Dim myDate As DateTime
  myDate = DateTime.Now() '// get current date and time
  Console.WriteLine(myDate)

  '//Parse : Convert from non standard datetime string to DateTime datatype, you can pass format or let .Net decide the best for you.
  '//This is less performant than ParseExact coz .Net has to check all possible date formats
  myDate = DateTime.Parse("9-30-2002") '//just pass a date and let .net decide whats the dateformat
  Console.WriteLine("Parse(9-30-2002) =>" & myDate)

  '//Parse: Culture specific
  Dim MyCultureInfo As Globalization.CultureInfo = New Globalization.CultureInfo("de-DE")
  Dim MyString As String = "12 Juni 2002"
  Dim MyDateTime As DateTime = DateTime.Parse(MyString, MyCultureInfo)
  Console.WriteLine("Culture Specific parsing =>" & MyDateTime)

  '//ParseExact : Converting nonstandard date format to DateTime datatype using ParseExact (match exact pattern)
  myDate = DateTime.ParseExact("09-05-2002 025612", "dd-MM-yyyy hhmmss", Nothing)
  Console.WriteLine("ParseExact(09-05-2002 025612) => " & myDate)
  myDate = DateTime.ParseExact("09052002", "ddMMyyyy", Nothing)
  Console.WriteLine("ParseExact(09052002) => " & myDate)
  myDate = DateTime.ParseExact("9-5-2002", "d-M-yyyy", Nothing)
  Console.WriteLine("ParseExact(9-5-2002) => " & myDate)
  myDate = DateTime.ParseExact("9-5-02", "d-M-yy", Nothing)
  Console.WriteLine("ParseExact(9-5-02) => " & myDate)

  '//ParseExact : Convert string to DateTime datatype using formats passes as array
  Dim allowedFomats() As String = {"ddMMyyyy", "d-MM-yyyy", "d-M-yy"}
  myDate = DateTime.ParseExact("9-01-02", allowedFomats, Nothing, Globalization.DateTimeStyles.None)
  Console.WriteLine("ParseExact using format array => " & myDate)
  Try
    '//try to parse date format other than allowedFomats
    myDate = DateTime.ParseExact("9 01 02", allowedFomats, Nothing, Globalization.DateTimeStyles.None)
  Catch ex As Exception
    Console.WriteLine(ex.Message)
  End Try
End Sub

Output:

8/2/2005 11:51:12 PM
Parse(9-30-2002) =>9/30/2002
Culture Specific parsing =>6/12/2002
ParseExact(09-05-2002 025612) => 5/9/2002 2:56:12 AM
ParseExact(09052002) => 5/9/2002
ParseExact(9-5-2002) => 5/9/2002
ParseExact(9-5-02) => 5/9/2002
ParseExact using format array => 1/9/2002
String was not recognized as a valid DateTime.

TimeSpan object

TimeSpan is another very useful object in VB.net. TimeSpan can represent time measured in Ticks which is 100 nanoseconds interval. You can store time interval as TimeSpan for easy manipulation with DateTime datatype. Let’s look at the example how you can use TimeSpan with DateTime datatype.

Example:

Click here to copy the following block

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
  Console.WriteLine("".PadRight(50, "="))
  Console.WriteLine("TimeSpan Demo")
  Console.WriteLine("".PadRight(50, "="))
  TimeSpanDemo()

  MsgBox("Check your output window (Clt + Alt + O)")
End Sub

Sub TimeSpanDemo()
  '//{0, -45} : Argument 0 , left aligned, width=45 chars
  Const headerFmt As String = vbCrLf & "{0,-45}"

  Console.WriteLine( _
    "This example of the TimeSpan class properties " & _
    "generates the " & vbCrLf & "following output. It " & _
    "creates several TimeSpan objects and " & vbCrLf & _
    "displays the values of the TimeSpan properties for " & _
    "each.")

  ' Create and display a TimeSpan value of 1 tick.
  Console.Write(headerFmt, "TimeSpan( 1 )")
  ShowTimeSpanProperties(New TimeSpan(1))

  ' Create a TimeSpan value with a large number of ticks.
  Console.Write(headerFmt, "TimeSpan( 111222333444555 )")
  ShowTimeSpanProperties(New TimeSpan(111222333444555))

  ' This TimeSpan has all fields overflowing.
  Console.Write(headerFmt, "TimeSpan( 1111, 2222, 3333, 4444, 5555)")
  ShowTimeSpanProperties(New TimeSpan(1111, 2222, 3333, 4444, 5555))

  ' This TimeSpan is based on a number of days.
  Console.Write(headerFmt, "FromDays( 20.84745602 )")
  ShowTimeSpanProperties(TimeSpan.FromDays(20.84745602))

  ' This TimeSpan is based on a number of seconds.
  Console.Write(headerFmt, "FromSeconds( 378452 )")
  ShowTimeSpanProperties(TimeSpan.FromSeconds(378452))

  ' This TimeSpan is based on a string.
  Console.Write(headerFmt, "TimeSpan.Parse(""99.23:59:59.9999999"")")
  ShowTimeSpanProperties(TimeSpan.Parse("99.23:59:59.9999999"))

  '//add/subtract timespan to datetime
  Dim dt As New DateTime(2005, 2, 28)
  dt = dt.Add(TimeSpan.Parse("2.02:56:30.999").Duration) ' add 2 days, 2hrs, 56 mins, 30 sec and 999 milisec
  Console.WriteLine("Add TimeSpan : " & dt.ToString("MMM dd, yyyy hh:mm:ss.fff tt"))

  '//get difference of 2 datetimes in timespan object
  Dim dt1, dt2 As DateTime
  Dim ts As TimeSpan
  dt1 = "1/1/2005 02:00:00 PM"
  dt2 = "1/1/2006 03:30:50 PM"

  ts = dt2.Subtract(dt1)
  Console.WriteLine("ts=dt1.subtract(dt1) : " & ts.ToString)
End Sub

' Display the properties of the TimeSpan parameter.
Sub ShowTimeSpanProperties(ByVal interval As TimeSpan)
  Const dataFmt As String = "{0,-12}{1,8}    {2,-18}{3,21}"

  Console.WriteLine("{0,21}", interval)
  Console.WriteLine(dataFmt, "Days", interval.Days, "TotalDays", interval.TotalDays)
  Console.WriteLine(dataFmt, "Hours", interval.Hours, "TotalHours", interval.TotalHours)
  Console.WriteLine(dataFmt, "Minutes", interval.Minutes, "TotalMinutes", interval.TotalMinutes)
  Console.WriteLine(dataFmt, "Seconds", interval.Seconds, "TotalSeconds", interval.TotalSeconds)
  Console.WriteLine(dataFmt, "Milliseconds", interval.Milliseconds, "TotalMilliseconds", interval.TotalMilliseconds)
  Console.WriteLine(dataFmt, Nothing, Nothing, "Ticks", interval.Ticks)
End Sub

Output:

==================================================
TimeSpan Demo
==================================================
This example of the TimeSpan class properties generates the 
following output. It creates several TimeSpan objects and 
displays the values of the TimeSpan properties for each.

TimeSpan( 1 )                                     00:00:00.0000001
Days               0       TotalDays          1.15740740740741E-12
Hours              0       TotalHours         2.77777777777778E-11
Minutes            0       TotalMinutes       1.66666666666667E-09
Seconds            0       TotalSeconds                      1E-07
Milliseconds       0       TotalMilliseconds                0.0001
                           Ticks                                 1

TimeSpan( 111222333444555 )                   128.17:30:33.3444555
Days             128       TotalDays              128.729552597865
Hours             17       TotalHours             3089.50926234875
Minutes           30       TotalMinutes           185370.555740925
Seconds           33       TotalSeconds           11122233.3444555
Milliseconds     344       TotalMilliseconds      11122233344.4555
                           Ticks                   111222333444555

TimeSpan( 1111, 2222, 3333, 4444, 5555)      1205.22:47:09.5550000
Days            1205       TotalDays              1205.94941614583
Hours             22       TotalHours                28942.7859875
Minutes           47       TotalMinutes              1736567.15925
Seconds            9       TotalSeconds              104194029.555
Milliseconds     555       TotalMilliseconds          104194029555
                           Ticks                  1041940295550000

FromDays( 20.84745602 )                        20.20:20:20.2000000
Days              20       TotalDays              20.8474560185185
Hours             20       TotalHours             500.338944444444
Minutes           20       TotalMinutes           30020.3366666667
Seconds           20       TotalSeconds                  1801220.2
Milliseconds     200       TotalMilliseconds            1801220200
                           Ticks                    18012202000000

FromSeconds( 378452 )                                   4.09:07:32
Days               4       TotalDays              4.38023148148148
Hours              9       TotalHours             105.125555555556
Minutes            7       TotalMinutes           6307.53333333333
Seconds           32       TotalSeconds                     378452
Milliseconds       0       TotalMilliseconds             378452000
                           Ticks                     3784520000000

TimeSpan.Parse("99.23:59:59.9999999")          99.23:59:59.9999999
Days              99       TotalDays              99.9999999999988
Hours             23       TotalHours             2399.99999999997
Minutes           59       TotalMinutes           143999.999999998
Seconds           59       TotalSeconds            8639999.9999999
Milliseconds     999       TotalMilliseconds       8639999999.9999
                           Ticks                    86399999999999
Add TimeSpan : Mar 02, 2005 02:56:30.999 AM
ts=dt1.subtract(dt1)  : 365.01:30:50