# Function Reference

# _DateToDayOfWeekISO

Returns the ISO weekday number for a given date

#include <Date.au3>
_DateToDayOfWeekISO ( $iYear, $iMonth, $iDay )

## Parameters

$iYear | A valid year in format YYYY
$iMonth | A valid month in format MM
$iDay | A valid day in format DD

## Return Value

Success: | the day of the Week Range is 1 to 7 where 1=Monday.
Failure: | 0 and sets the @error flag to non-zero.
@error: | 1 - Invalid Input Date

## Related

_DateAdd, _DateDayOfWeek, _DateDiff, _DateToDayOfWeek, _DayValueToDate

## Example

    #include <Date.au3>
    #include <MsgBoxConstants.au3>

    ; ISO week day number for a given date 1 = Monday - 7 = Sunday
    Local $iWeekday = _DateToDayOfWeekISO(@YEAR, @MON, @MDAY)
    ; NOT equal to @WDAY
    MsgBox($MB_SYSTEMMODAL, "", "Today's ISO week day number is: " & $iWeekday)