Safely Enter Date String into TDateTimePicker

in your program you can set the regional settings for your program

at startup you can set any of the global delphi variables

Application.UpdateFormatSettings := False;
will make sure they stay like that when somebody changes windows regional settings while your program is running

procedure TMainForm.FormCreate(Sender: TObject);
begin
  DecimalSeparator := '.';
  ShortDateFormat := 'YYYY-MM-DD';
  Application.UpdateFormatSettings := False;
end;

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Geert:

Thanks for your suggestion, but I would still like the user to see the date in the format they expect to see it, otherwise they're likely to enter the wrong value.

I know I can convert the date properly from the DateTimePicker (in fact I do that already), I just don't know how to put it back into the DateTimePicker correctly. Any other suggestions?

 

function YourStrToDate(aString: string): TDateTime;
var sdf: string;
begin
  sdf := ShortDateFormat;
  try
    ShortDateFormat := 'YYYY-MM-DD';
    Result := StrToDate(aString);
  finally
    ShortDateFormat := sdf;
  end;
end;

the use that result to set the Data in the DateTimePicker

dtp.Date := YourStrToDate('2009-12-31');

Geert:

This is almost exactly the code I tried myself, but both yours and mine return the same exception:

EConvertError ... ''2008-12-31' is not a valid date'.

:(

Well you could you use
TryStrToDate or TryStrToDateTime

From Delphi Help File
Call TryStrToDateTime to parse a string that specifies a date and time value. If S does not contain a valid date, TryStrToDateTime returns false.

The above applies to TryStrToDate

function TryStrToDateTime(const S: string; out Value: TDateTime): Boolean; overload;
function TryStrToDate(const S: string; out Value: TDateTime): Boolean; overload;

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gtrifidis:

Thanks for the heads up on the functions, they should prove useful, but I'm not sure how they solves the current problem. If you have a clever use for these, I'm all ears! :)

Thanks for hanging in there. This answer was a great help!