[Bug] asDateTime conversion error! 4 digit milisec 2025-12-12 12:12:12.1230

[dbannon]

....
Bottom line: it‘s the user’s responsibility to truncate/round exceeding decimals after the 3rd decimal BEFORE sending it to any Parsing Function

Not if you use the iso8601 methods. eg -

Code: Pascal  [Select][+][-]

1. program testdate;
2. {$mode objfpc}
3.  
4. uses dateutils;
5. var
6. DateTime, DateTime2 : TDateTime;
7.  
8. begin
9.         if TryISO8601ToDate('2025-12-19T10:45:00.123456', DateTime) then
10.                 writeln('Convert to DateTime OK');
11.         if TryISO8601ToDate('2025-12-19T10:45:00.123', DateTime2) then
12.                 writeln('Convert to DateTime2 OK');
13.         writeln('Diff is ', DateTime - DateTime2);
14. end.

Code: Bash  [Select][+][-]

1. dbannon@dell:~/Pascal/CLI$ ./test_date
2. Convert to DateTime OK
3. Convert to DateTime2 OK
4. Diff is  5.2750692702829838E-009

Davo

[wp]

On Windows the first output is missing, i.e. TryISO8601ToDate('2025-12-19T10:45:00.123456', DateTime) is not OK.

[cdbc]

Hi
On PCLinuxOS it looks like this:

Code: Bash  [Select][+][-]

1. [bc@stinker date-stuff]$ fpc test_date.pp
2. Free Pascal Compiler version 3.2.2 [2024/07/26] for x86_64
3. Copyright (c) 1993-2021 by Florian Klaempfl and others
4. Target OS: Linux for x86-64
5. Compiling test_date.pp
6. Linking test_date
7. 14 lines compiled, 1.2 sec
8. [bc@stinker date-stuff]$ ./test_date
9. Convert to DateTime2 OK
10. Diff is -4.6010447918090278E+004
11. [bc@stinker date-stuff]$
12.  

Same issue as with Werner...
Regards Benny

[dbannon]

Code: [Select]

[quote author=cdbc link=topic=73029.msg572609#msg572609 date=1766135288]
On PCLinuxOS it looks like this ...
[bc@stinker date-stuff]$ ./test_date
Convert to DateTime2 OK
Diff is -4.6010447918090278E+004

Oh, my code should report an error as well as success !  I and a little surprised WP had a problem on Windows (I use same basic idea in my app and its cross platform). But really surprised with PCLinux.

Will do some experimenting ....

Davo

[Zvoni]

Code: Pascal  [Select][+][-]

1. program testdate;
2. {$mode objfpc}
3.  
4. uses dateutils;
5. var
6. DateTime, DateTime2 : TDateTime;
7.  
8. begin
9.         if TryISO8601ToDate('2025-12-19T10:45:00.123456', DateTime) then
10.                 writeln('Yeet DateTime') Else Writeln('No Yeet Datetime');
11.         if TryISO8601ToDate('2025-12-19T10:45:00.123', DateTime2) then
12.                 writeln('Yeet DateTime2') Else Writeln('No Yeet Datetime2');
13.         writeln('Diff is ', DateTime - DateTime2);
14.         Readln;
15. end.

Returns

Code: [Select]

Yeet DateTime
Yeet DateTime2
Diff is  5.2750692702829838E-009
Win10-64-Bits - FPC3.2.3/Laz4.3 (old fixes)

[paweld]

As @Zvoni wrote, it is OK in FPC 3.2-fixes, but in FPC 3.2.2 TryISO8601ToDate(‘2025-12-19T10:45:00.123456’, DateTime) is not. Tested on Windows 10.

[dbannon]

Ah, yes paweld, just writing up the same explanation.

WP, Benny, are you using FPC322 ?

Looks like this is one of the many things that have been fixed in FPC323. I took my binary (compiled with fpc324rc1) to a PCLinux VM and it worked as expected. So I took the source and compiled it on PCLinux and it fails.

So, looking in the source of my App (which must compile with FPC322 on Debian) I realize I work around that problem. I vaguely recall reporting the issue and 'someone' fixed it, possibly PascalDragon. But of course, its not in the "Released Version" of FPC yet. Sigh ....

Code: Pascal  [Select][+][-]

1. function MyTryISO8601ToDate(DateSt : string; out OutDT : TDateTime; ReturnUTC : boolean = true) : boolean;
2. var
3.     I : integer;
4.     St : string = '';
5. begin
6.     OutDT := 0.0;
7.     if DateSt = '' then exit(False);
8.     Result := True;
9.     I := pos('.', DateSt);                          // if we have decimal point, we have stuff to do.
10.     if I > 0 then begin                             // TryISO8601ToDate cannot handle string with decimals of a second
11.         delete(DateSt, I, 1);                       // Remove decimal point
12.         while I  < length(DateSt) do begin
13.             if DateSt[I] in ['0'..'9'] then begin
14.                 St := St + DateSt[I];               // save digits to use later
15.                 delete(DateSt, I, 1);
16.             end else break;
17.         end;
18.         // The first six digits in St represent microseconds. we will stop there.
19.         while length(St) > 6 do delete(St, length(St), 1);
20.         while length(St) < 6 do St := St + '0';
21.     end;
22.     if TryISO8601ToDate(DateSt, OutDT, ReturnUTC) then begin               // WARNING - apparently this is a FPC320 only feature
23.         if I > 0 then
24.             OutDT := OutDT + (St.ToDouble() * ValueMicroSecond);           // ValueMicroSecond is Regional const,  eg
25.         end else result := False;                                              // ValueMicroSecond := 1.0 / double(24*60*60*1000*1000);
26. end;

                                                                                                                                   

Davo

[cdbc]

Hi Davo
Right, sorry I was a lazy bastard...
This time compiled with 2 weeks old 'main' ~ fpc 3.3.1:

Code: Bash  [Select][+][-]

1. [bc@stinker date-stuff]$ ./test_date
2. Convert to DateTime OK
3. Convert to DateTime2 OK
4. Diff is  5.2750692702829838E-009
5. [bc@stinker date-stuff]$
6.  

Regards Benny