Hi,
How do I convert string with HTTP date format such as Wed, 29 Apr 2020 10:35:50 GMT
back to its TDateTime value?
I try with ScanDateTime()
adateTime := ScanDateTime(     'ddd", "dd" "mmm" "yyyy" "hh:mm:ss" GMT"',     'Wed, 29 Apr 2020 10:35:50 GMT'); but EConvertError exception is raised with message  Mismatch char " " "," at pattern position 5, string position 5

ZamroniFano Framework https://fanoframework.github.io

Zamrony P. Juhara

Can't test, but from the docs shouldn't it be something like:

adateTime := ScanDateTime(
'ddd, dd mmm yyyy hh:mm:ss GMT',
'Wed, 29 Apr 2020 10:35:50 GMT');

No it does not work. Docs says literal string needs to be quoted with "

Zamrony P. Juhara

On Wed, Apr 29, 2020 at 9:37, Alexander Grotewohl wrote: _______________________________________________ fpc-pascal maillist  - 
https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal

"Note that to include any of the above characters literally in the result string, they must be enclosed in double quotes."

This only makes sense for FormatDateTime which returns a string you can display.

For example:
writeln(FormatDateTime(' "yyyy" = yyyy ', now));

To print:
yyyy = 2020

I try with your suggested pattern format but it does not work either. Same EConvertError with different error message. I guess, I have to parse it manually

Zamrony P. Juhara
https://v3.juhara.com
https://github.com/zamronypj

Fano Framework
https://fanoframework.github.io

mod_pascal
https://zamronypj.github.io/mod_pascal

On Wed, Apr 29, 2020 at 10:00, Alexander Grotewohl wrote: _______________________________________________ fpc-pascal maillist  - 
https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal

This format works for me:
'ddd, dd mmm yyyy hh:nn:ss'
Fpc 3.04, windows 7, 32bits, and fpc 3.04, Linux, 64bits.

Some points:

* "m" is allowed for minutes , nevertheless, I use for minutes "n", not "m".
* I have suppressed the time zone information, I couldn't see how to set it in formatStrings, nevertheless, it ignores the GMT, or anything after time in input string with no error.
* I think that the scanner ignores the character after weekday, it expects a separator, as long as it is not a "d" if will accept and skip anything. So the double quote after the three "d" of 'ddd", "dd is ignored and everything breaks. It's a little confusing.
* The weekday and month depend on you local.
* using non-ascii characters breaks things. In Spanish Wednesday is "Miércoles" (e with acute accent) and Tuesday is "Martes": "mar, 28 abr 2020" works, but "Mié, 29 Abr 2020" fails. I think that the problem is that é  uses two bytes in UTF-8, but scan only deals properly with single byte characters

Yes, it works if I remove timezone part from pattern as suggested by Santiago. This one works adatetime := scanDateTime(     'ddd, dd mmm yyyy hh:mm:ss',     'Tue, 28 Apr 2020 10:11:12 GMT'); So i guess, we must convert timezone information to local timezone manually.

Thank you
Zamrony P. Juhara
https://v3.juhara.com
https://github.com/zamronypj

Fano Framework
https://fanoframework.github.io

mod_pascal
https://zamronypj.github.io/mod_pascal

On Wed, Apr 29, 2020 at 16:40, Santiago A. wrote: _______________________________________________ fpc-pascal maillist  - 
https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal

yes.
In unit Dateutils
https://www.freepascal.org/docs-html/rtl/dateutils/index-5.html You have a lot of handy functions:

function UniversalTimeToLocal(

  UT: TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>

):TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>;
function UniversalTimeToLocal(
   UT: TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>;

  TZOffset: Integer
<https://www.freepascal.org/docs-html/rtl/system/integer.html>

):TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>;
function LocalTimeToUniversal(

  LT: TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>

):TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>;
function LocalTimeToUniversal(
   LT: TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>;

  TZOffset: Integer
<https://www.freepascal.org/docs-html/rtl/system/integer.html>

):TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>;
function UniversalTimeToLocal(

  UT: TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>

):TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>;
function UniversalTimeToLocal(
   UT: TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>;

  TZOffset: Integer
<https://www.freepascal.org/docs-html/rtl/system/integer.html>

):TDateTime
<https://www.freepascal.org/docs-html/rtl/system/tdatetime.html>;
function GetLocalTimeOffset: Integer
<https://www.freepascal.org/docs-html/rtl/system/integer.html>;