[Solved] ScanDateTime error in Sep

[ALAU2007]

I convert string '01 Sep 2025' to date, it shows:

  Can't match any allowed value at pattern position 4, string position 4

The other month is OK, only the Sep has error:

procedure TForm1.Button1Click(Sender: TObject);
var tDate: TDateTime;
begin
  tDate := scandatetime( 'dd mmm yyyy', '01 Jan 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 sep 2025' );  // Error
  ShowMessage( DateToStr( tDate ));
end;

Please comment.

[dsiders]

I convert string '01 Sep 2025' to date, it shows:

  Can't match any allowed value at pattern position 4, string position 4

The other month is OK, only the Sep has error:

procedure TForm1.Button1Click(Sender: TObject);
var tDate: TDateTime;
begin
  tDate := scandatetime( 'dd mmm yyyy', '01 Jan 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 sep 2025' );  // Error
  ShowMessage( DateToStr( tDate ));
end;

Please comment.

Does you system use English month names in FormatSettings.ShortMonthNames? Cause that's what you told ScanDateTijme() to look for.

[paweld]

As @dsiders wrote, probably your system's regional settings are not English. You need to define an array of short month names in English

Code: Pascal  [Select][+][-]

1. uses
2.   DateUtils;
3.  
4. procedure TForm1.Button1Click(Sender: TObject);
5. var
6.   s: String;
7.   dt: TDateTime;
8.   fs: TFormatSettings;
9. begin
10.   fs := DefaultFormatSettings;
11.   //if your system locale is not in English, then you need to define short month names
12.   fs.ShortMonthNames[1] := 'Jan';
13.   fs.ShortMonthNames[2] := 'Feb';
14.   fs.ShortMonthNames[3] := 'Mar';
15.   fs.ShortMonthNames[4] := 'Apr';
16.   fs.ShortMonthNames[5] := 'May';
17.   fs.ShortMonthNames[6] := 'Jun';
18.   fs.ShortMonthNames[7] := 'Jul';
19.   fs.ShortMonthNames[8] := 'Aug';
20.   fs.ShortMonthNames[9] := 'Sep';
21.   fs.ShortMonthNames[10] := 'Oct';
22.   fs.ShortMonthNames[11] := 'Nov';
23.   fs.ShortMonthNames[12] := 'Dec';
24.   //
25.   s := '01 Jan 2025';
26.   dt := ScanDateTime('d mmm yyyy', s, fs);
27.   ShowMessage(DateToStr(dt));
28.   //
29.   s := '01 sep 2025';
30.   dt := ScanDateTime('d mmm yyyy', s, fs);
31.   ShowMessage(DateToStr(dt));
32. end;  

[ALAU2007]

Thanks paweld and dsiders.

After defining the ShortMonthName, It works.  BTW, I have tried the other months is OK, except the "Sep" has the error.  I have tried as

procedure TForm1.Button1Click(Sender: TObject);
var tDate: TDateTime;
begin
  tDate := scandatetime( 'dd mmm yyyy', '01 Oct 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 Nov 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 Dec 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 Aug 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 Jul 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 Jun 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 May 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 Apr 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 Mar 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 Feb 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 Jan 2025' );
  tDate := scandatetime( 'dd mmm yyyy', '01 sep 2025' );
  tDate := formatdatetime( 'dd mmm yyyy', '01 sep 2025' );   // only it has error when shortMonthNme is not defined.
  ShowMessage( DateToStr( tDate ));
end;

[cdbc]

Hi
Just an observation:
- I believe the 'ScanDateTime' function is case-sensitive:

Code: Pascal  [Select][+][-]

1.   tDate := scandatetime( 'dd mmm yyyy', '01 sep 2025' );

That would mean 'sep' is different from 'Sep'!
I noticed all the other months were with a versal, e.g.: '(J)an' --> not '(j)an'.
Regards Benny

[paweld]

@cdbc: is not case-sensitive - uses the function: https://docs.freepascal.org/docs-html/rtl/sysutils/ansistrlicomp.html

Edit:
@ALAU2007: you may want to check how you have short month names defined, such as:

Code: Pascal  [Select][+][-]

1. uses
2.   DateUtils;
3.  
4. procedure TForm1.FormCreate(Sender: TObject);
5. var
6.   i: Integer;
7.   s: String;
8. begin
9.   s := '';
10.   for i := Low(DefaultFormatSettings.ShortMonthNames) to High(DefaultFormatSettings.ShortMonthNames) do
11.     s := s + Format('%2d -> %s'#13#10, [i, DefaultFormatSettings.ShortMonthNames[i]]);
12.   ShowMessage(s);
13. end;