[Overview][Constants][Procedures and functions][Index] Reference for unit 'DateUtils' (#rtl)

# IsValidDateWeek

Check whether a given year/week/day of the week combination is a valid day.

## Declaration

Source position: dateutil.inc line 102

 function IsValidDateWeek( const AYear: Word; const AWeekOfYear: Word; const ADayOfWeek: Word ):Boolean;

## Arguments

 AYear Year AWeekOfYear Week in the year ADayOfWeek Day in the week

## Function result

True if the given combination is a valid date, False otherwise.

## Description

IsValidDateWeek returns True if AYear, AWeekOfYear and ADayOfWeek form a valid date indication, or False otherwise.

AYear must be in the range 1..9999 to be valid.

The ADayOfWeek,ADayOfWeek values are checked to see whether the combination falls within the valid range of weeks for AYear.

 IsValidDate Check whether a set of values is a valid date indication. IsValidTime Check whether a set of values is a valid time indication. IsValidDateTime Check whether a set of values is a valid date and time indication. IsValidDateDay Check whether a given year/day of year combination is a valid date. IsValidDateMonthWeek Check whether a given year/month/week/day of the week combination is a valid day

## Example

```Program Example10;

{ This program demonstrates the IsValidDateWeek function }

Uses SysUtils,DateUtils;

Var
Y,W,D : Word;
B : Boolean;

Begin
For Y:=2000 to 2004 do
begin
B:=True;
For W:=51 to 54 do
For D:=1 to 7 do
If B then
begin
B:=IsValidDateWeek(Y,W,D);
If Not B then
if (D=1) then
Writeln(Y,' has exactly ',W,' weeks.')
else
Writeln(Y,' has ',W,' weeks and ',D-1,' days.');
end;
end;
End.
```