DatePart Function

DatePart Function

Class

Microsoft.VisualBasic.DateAndTime

Syntax

 DatePart(   interval   ,   datevalue   [,   firstdayofweekvalue   [, _   firstweekofyearvalue   ]])

interval (required; String or a member of the DateInterval enum): A String literal (see the second item in Section ) or a constant of the DateInterval enum (see the third item in Section ) that defines the part of the date/time to extract from datevalue
datevalue (required; Date, literal date, or an expression capable of conversion to a date): The Date value to evaluate
firstdayofweekvalue (optional; FirstDayOfWeek enum): A member of the FirstDayOfWeek enum
firstweekofyearvalue (optional; FirstWeekOfYear enum): A member of the FirstWeekOfYear enum

Return Value

An Integer containing the specified part

Description

Extracts an individual component of the date or time (like the month or the second) from a date/time value

Rules at a Glance

The DatePart function returns an Integer containing the specified portion of the given date. DatePart is a single function encapsulating the individual Year , Month , Day , Hour , Minute , and Second functions.
interval can be one of the following literal strings:

String	Description
yyyy	Year
q	Quarter
m	Month
y	Day of year
d	Day
w	Weekday
ww	Week
h	Hour
n	Minute
s	Second

interval can also be a member of the DateInterval enum:

 Enum DateInterval    Day    DayOfYear    Hour    Minute    Month    Quarter    Second    Week    Weekday    WeekOfYear End Enum

The firstdayofweekvalue argument can be any of the following members of the FirstDayOfWeek enumeration:

 Enum FirstDayOfWeek    System     'uses first day of week setting on local system    Sunday    Monday    Tuesday    Wednesday    Thursday    Friday    Saturday End Enum

The firstdayofweekvalue argument affects only calculations that use either the Week (or "w" ) or Weekday (or "ww" ) interval values.
The firstweekofyearvalue argument can be any of the following members of the FirstWeekOfYear enumeration:

FirstWeekOfYear constant	Value	Description
System		Uses the local system setting
Jan1	1	Starts with the week in which January 1 occurs (the default value)
FirstFourDays	2	Starts with the first week that has at least four days in the new year
FirstFullWeek	3	Starts with the first full week of the year

Example

 MsgBox("Current hour: " & DatePart(DateInterval.Hour, Now))

Programming Tips and Gotchas

When working with dates, always check that a date is valid using the IsDate function prior to passing it as a function parameter.
If you attempt to extract the hours, minutes, or seconds, but datevalue does not contain the necessary time element, the function assumes a time of midnight (0:00:00).
If you specify datevalue within quotation marks ( " " ) and omit the year, the year is assumed to be the current year taken from the computer's date. For example:
```
 Console.WriteLine(DatePart(DateInterval.Year, cDate("01/03"))) 
```

VB.NET/VB 6 Differences

VB 6 lacks the DateInterval enumeration and therefore only accepts a string as the interval argument.
VB 6 supports a number of constants beginning with vb ... as values for the firstdayofweekvalue and firstweekofyearvalue arguments . While these are still supported in VB.NET, VB.NET has also added the FirstDayOfWeek and FirstWeekOfYear enumerations.