Name

Weekday Function

Class

Microsoft.VisualBasic.DateAndTime

Syntax

Weekday(datevalue, [dayofweek])
date

Use: Required

Data Type: Date or valid date expression

Any valid date expression

dayofweek

Use: Optional

Data Type: Constant of FirstDayOfWeek enumeration

A constant indicating the first day of the week

Return Value

Integer

Description

Determines the day of the week of a given date

Rules at a Glance

  • The default for dayofweek is FirstDayOfWeek.Sunday.

  • To determine the day of the week, think of the day specified by dayofweek as day 1, and the value returned by the function as indicating the day relative to day 1. Then, for example, if the return value of WeekDay is 2, this specifies the day following dayofweek. A return value of 1 specifies dayofweek. A return value of 7 specifies the day before dayofweek.

  • The members of the FirstDayOfWeek enumeration are:

    Constant

    Value

    Description

    Sunday

    1

    Sunday

    Monday

    2

    Monday

    Tuesday

    3

    Tuesday

    Wednesday

    3

    Wednesday

    Thursday

    4

    Thursday

    Friday

    5

    Friday

    Saturday

    6

    Saturday

    Sunday

    7

    Sunday

  • Passing a value of 0 as the dayofweek argument uses the system’s locale settings to determine the first day of the week.

Example

Since the code:

Weekday(#3/26/2001#, FirstDayOfWeek.Sunday)

returns 2, the date 3/26/2001 is a Monday.

Programming Tips and Gotchas

  • If passing a date literal as datevalue, the Weekday function requires that all four digits of the year be present.

  • That the function’s return value is relative to dayofweek ...

Get VB .NET Language in a Nutshell now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.