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Date Data Type (Visual Basic)

  • บทความ

Holds IEEE 64-bit (8-byte) values that represent dates ranging from January 1 of the year 0001 through December 31 of the year 9999, and times from 12:00:00 AM (midnight) through 11:59:59.9999999 PM. Each increment represents 100 nanoseconds of elapsed time since the beginning of January 1 of the year 1 in the Gregorian calendar. The maximum value represents 100 nanoseconds before the beginning of January 1 of the year 10000.

Remarks

Use the Date data type to contain date values, time values, or date and time values.

The default value of Date is 0:00:00 (midnight) on January 1, 0001.

You can get the current date and time from the DateAndTime class.

Format Requirements

You must enclose a Date literal within number signs (# #). You must specify the date value in the format M/d/yyyy, for example #5/31/1993#, or yyyy-MM-dd, for example #1993-5-31#. You can use slashes when specifying the year first. This requirement is independent of your locale and your computer's date and time format settings.

The reason for this restriction is that the meaning of your code should never change depending on the locale in which your application is running. Suppose you hard-code a Date literal of #3/4/1998# and intend it to mean March 4, 1998. In a locale that uses mm/dd/yyyy, 3/4/1998 compiles as you intend. But suppose you deploy your application in many countries/regions. In a locale that uses dd/mm/yyyy, your hard-coded literal would compile to April 3, 1998. In a locale that uses yyyy/mm/dd, the literal would be invalid (April 1998, 0003) and cause a compiler error.

Workarounds

To convert a Date literal to the format of your locale, or to a custom format, supply the literal to the Format function, specifying either a predefined or user-defined date format. The following example demonstrates this.

MsgBox("The formatted date is " & Format(#5/31/1993#, "dddd, d MMM yyyy"))

Alternatively, you can use one of the overloaded constructors of the DateTime structure to assemble a date and time value. The following example creates a value to represent May 31, 1993 at 12:14 in the afternoon.

Dim dateInMay As New System.DateTime(1993, 5, 31, 12, 14, 0)

Hour Format

You can specify the time value in either 12-hour or 24-hour format, for example #1:15:30 PM# or #13:15:30#. However, if you do not specify either the minutes or the seconds, you must specify AM or PM.

Date and Time Defaults

If you do not include a date in a date/time literal, Visual Basic sets the date part of the value to January 1, 0001. If you do not include a time in a date/time literal, Visual Basic sets the time part of the value to the start of the day, that is, midnight (0:00:00).

Type Conversions

If you convert a Date value to the String type, Visual Basic renders the date according to the short date format specified by the run-time locale, and it renders the time according to the time format (either 12-hour or 24-hour) specified by the run-time locale.

Programming Tips

  • Interop Considerations. If you are interfacing with components not written for the .NET Framework, for example Automation or COM objects, keep in mind that date/time types in other environments are not compatible with the Visual Basic Date type. If you are passing a date/time argument to such a component, declare it as Double instead of Date in your new Visual Basic code, and use the conversion methods DateTime.FromOADate and DateTime.ToOADate.

  • Type Characters. Date has no literal type character or identifier type character. However, the compiler treats literals enclosed within number signs (# #) as Date.

  • Framework Type. The corresponding type in the .NET Framework is the System.DateTime structure.

Example

A variable or constant of the Date data type holds both the date and the time. The following example illustrates this.

Dim someDateAndTime As Date = #8/13/2002 12:14 PM#

See also