CODEWITHSUNDEEP
delphi
mcdon
mcdon

Reputation: 5059

Delphi require 4 digit year

A user will enter a string value for a date. StrToDate will be used to convert the string value to a DateTime. If the user enter's a date with a 2 digit year the date may be parsed as the current century (20xx) or the previous century (19xx).

To clear up any ambiguity, how do require the user enter a 4 digit year?

if isFourDigitYear(txbDate.Text) then
  date := StrToDate(txbDate.Text)
else
  ShowMessage('enter date with 4 digit year');

Upvotes: 1

Views: 632

Answers (2)

SilverWarior
SilverWarior

Reputation: 8386

I think that the best choice would be to use TDateTimePicker

http://docwiki.embarcadero.com/Libraries/XE6/en/Vcl.ComCtrls.TDateTimePicker

If you are using older Delphi than Delphi 2009 with update pack 3 then you would wanna read next article to fix a bug found in TDateTimePicker.

http://www.tmssoftware.com/site/blog.asp?post=117

This bug has been fixed in newer versions.

Now if you are using FireMonkey take care about using TDateTimePicker as in Delphi XE3 it has a bug which srews up the date when entered through keyboard (can still be picked fine by mouse). I'm not sure if this was already fixed in later versions of Delphi or not.

If using of TDateTimePicker is out of the question then definitly use TMaskedEdit instead of regular TEdit since the chosen mask forces user to enter in text in proper format.

http://docwiki.embarcadero.com/CodeExamples/XE6/en/EditMask_(Delphi)

EDIT: The best advantage of using TDateTimePicker is that it automatically uses Date Time format that has been set on that specific system.

This means that date time format used will be the one user is used to. So there will be no mistakes in case if user local settings use dd/mm/yy format instead of mm/dd/yy.

Upvotes: 1

HeartWare
HeartWare

Reputation: 8261

One possibility is this:

FUNCTION IsFourDigitYear(DateStr : STRING ; DateSep : CHAR = '/') : BOOLEAN;
  VAR
    P   : Cardinal;

  BEGIN
    DateStr:=DateStr+DateSep; Result:=TRUE;
    REPEAT
      P:=POS(DateSep,DateStr);
      IF P=5 THEN EXIT;
      DELETE(DateStr,1,P)
    UNTIL DateStr='';
    Result:=FALSE
  END;

It will check that there is a part of the given string that has 4 characters.

It currently won't check if that part is numerical (ie. only contains digits). And it will require you to pass in the seperator character used if you want it to be truly international - there are some countries that use '-' as a date seperator, and most other countries in the world doesn't use the strange M/D/Y format, but either D/M/Y or Y/M/D format (where "/" may be "-" in some countries).

If you want a truly international function that also checks if the four-digit part is actually in the year part of the currently valid date format, then it'll need a much more complex parser. The above may get you started, however...

Upvotes: 0

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