## 2005. április 14., csütörtök

### Convert a RFC time string into TDateTime and VV

Problem/Question/Abstract:

How to convert a RFC time string into TDateTime and vv.

Answer:

Conversion of date & time formats: RFC <-> TDateTime (local & UNC) RFC: e.g. 03.01.2001 05:45:00 -0500

TDateTime -> RFC use

DateTimeToRfcTime(date, diff, gmt)

RFC -> TDateTime  use

RfcTimeToDateTime(time, gmt)

function DateTimeToRfcTime(
dt: TDateTime;
iDiff: integer;
blnGMT: boolean = false): string;
{*
Explanation:
iDiff is the local offset to GMT in minutes
if blnGMT then Result is UNC time else local time
e.g. local time zone: ET = GMT - 5hr = -300 minutes
dt is TDateTime of 3 Jan 2001 5:45am
blnGMT = true  -> Result = 'Wed, 03 Jan 2001 05:45:00 GMT'
blnGMT = false -> Result = 'Wed, 03 Jan 2001 05:45:00 -0500'
*}
const
Weekday: array[1..7] of string =
('Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat');
Month: array[1..12] of string = (
'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec');
var
iDummy: Word;
iYear: Word;
iMonth: Word;
iDay: Word;
iHour: Word;
iMinute: Word;
iSecond: Word;
strZone: string;
begin
if blnGMT then
begin
dt := dt - iDiff / 1440;
strZone := 'GMT';
end
else
begin
iDiff := (iDiff div 60) * 100 + (iDiff mod 60);
if iDiff < 0 then
strZone := Format('-%.4d', [-iDiff])
else
strZone := Format('+%.4d', [iDiff]);
end;
DecodeDate(dt, iYear, iMonth, iDay);
DecodeTime(dt, iHour, iMinute, iSecond, iDummy);
Result := Format('%s, %.2d %s %4d %.2d:%.2d:%.2d %s', [
Weekday[DayOfWeek(dt)], iDay, Month[iMonth], iYear,
iHour, iMinute, iSecond, strZone]);
end;

function RfcTimeToDateTime(
strTime: string;
blnGMT: boolean = true): TDateTime;
{*
Explanation:
if blnGMT then Result is UNC time else local time
e.g. local time zone: ET = GMT - 5hr = -0500
strTime = 'Wed, 03 Jan 2001 05:45:00 -0500'
blnGMT = true  -> FormatDateTime('...', Result) = '03.01.2001 10:45:00'
blnGMT = false -> FormatDateTime('...', Result) = '03.01.2001 05:45:00'
*}
const
wd = 'sun#mon#tue#wed#thu#fri#sat';
month = 'janfebmaraprmayjunjulaugsepoctnovdec';
var
s: string;
dd: Word;
mm: Word;
yy: Word;
hh: Word;
nn: Word;
ss: Word;
begin
s := LowerCase(Copy(strTime, 1, 3));
if Pos(s, wd) > 0 then
Delete(strTime, 1, Pos(' ', strTime));
s := Trim(Copy(strTime, 1, Pos(' ', strTime)));
Delete(strTime, 1, Length(s) + 1);
dd := StrToIntDef(s, 0);
s := LowerCase(Copy(strTime, 1, 3));
Delete(strTime, 1, 4);
mm := (Pos(s, month) div 3) + 1;
s := Copy(strTime, 1, 4);
Delete(strTime, 1, 5);
yy := StrToIntDef(s, 0);
Result := EncodeDate(yy, mm, dd);
s := strTime[1] + strTime[2];
hh := StrToIntDef(strTime[1] + strTime[2], 0);
nn := StrToIntDef(strTime[4] + strTime[5], 0);
ss := StrToIntDef(strTime[7] + strTime[8], 0);
Delete(strTime, 1, 9);
Result := Result + EncodeTime(hh, nn, ss, 0);
if (CompareText(strTime, 'gmt') <> 0) and blnGMT then
begin
hh := StrToIntDef(strTime[2] + strTime[3], 0);
nn := StrToIntDef(strTime[4] + strTime[5], 0);
if strTime[1] = '+' then
Result := Result - EncodeTime(hh, nn, 0, 0)
else
Result := Result + EncodeTime(hh, nn, 0, 0);
end;
end;