How to convert to TDateTime an string formatted this way: 15h44m28s?

Question

I have file names encoded with datetimes in the format:yyyy-mm-dd_HHhMMhSSs.
Real example: 2013-08-05_15h44m28s (in the time portion, it can have only the hour part)

I have to convert it back to an actual datetime. The date part is so easy that it's already solved, but for the time portion I didn't found in my delphi install a way to do that out-of-the-box.

So I got an SScanf implementation to solve that, but the question remains: did I overlook something or it's indeed the way to do that without having to write code myself?

Note: although I tagged my delphi version, functions that exist in more recent versions are interesting too.
BTW, someone knows if that formatting of the time portion have an name?

@SirRufo So convert this comment in an answer so I can accept that. — Fabricio Araujo, Jan 22 '14 at 18:35
@SirRufo: Not really, I believe that only the date part can be obtained using the TFormatSettings. I may be wrong. — Fabricio Araujo, Jan 22 '14 at 18:42
@SirRufo: confirmed, converting the time part using TFormatSettings parameters is not possible. The linked question, however, can be solved using it. — Fabricio Araujo, Jan 22 '14 at 18:50
`VarToDateTime` can handle a lot of more formats than `StrToDateTime` but not everything :o) — Sir Rufo, Jan 22 '14 at 18:53
I know it's trivial, @DavidHeffernan. But since it's an last hour request so I got an SScanf to do that. I'm just checking if I overlooked something. — Fabricio Araujo, Jan 22 '14 at 19:21
Why not use simple `Copy` to extract each element? It appears the format is fixed, so you know exactly where each element is located. — Disillusioned, Jan 22 '14 at 22:34
I don't agree it's a duplicate, since the solution given is to copy LCL code and I'm asking for an Delphi's RTL solution - which @SirRufo confirm does not exist an direct function, but mr.Heffernan showed how to do with regex (and it's out-of-box). — Fabricio Araujo, Jan 23 '14 at 13:22

score 3 · Accepted Answer · edited Jan 22 '14 at 20:26

3

This is a good use case for a regex. Once you pulled off the date then you can use this regex:

(\d+)h(\d+)m(\d+)s

In fact, you may as well parse the entire string that way. All you need is this function:

function ToDateTime(const str: string): TDateTime;
var
  Match: TMatch;
begin
  Match := TRegEx.Match(str, '(\d+)-(\d+)-(\d+)_(\d+)h(\d+)m(\d+)s');
  if Match.Groups.Count<>7 then
    raise Exception.CreateFmt('Could not parse date/time: %s', [str]);
  Result := EncodeDateTime(
    StrToInt(Match.Groups[1].Value),
    StrToInt(Match.Groups[2].Value),
    StrToInt(Match.Groups[3].Value),
    StrToInt(Match.Groups[4].Value),
    StrToInt(Match.Groups[5].Value),
    StrToInt(Match.Groups[6].Value),
    0
  );
end;

edited Jan 22 '14 at 20:26

HeartWare

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answered Jan 22 '14 at 19:49

David Heffernan

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It's out-of-box, so I overlooked the fact that xe2 does support regex. TYVM. – Fabricio Araujo Jan 23 '14 at 13:24
But still have to modify it to allow to have only the hour part. – Fabricio Araujo Jan 23 '14 at 13:27
Test for `'(\d+)-(\d+)-(\d+)_(\d+)h(\d+)m(\d+)s'` first, and if that fails, test for `'(\d+)-(\d+)-(\d+)_(\d+)h'` – David Heffernan Jan 23 '14 at 13:32

How to convert to TDateTime an string formatted this way: 15h44m28s?

1 Answers1