Delphi

StringをUTF-8フォーマットに変換

uses Windows;
function ToUTF8(s: String): String;
var
  ws: WideString;
  len: Integer;
begin
  ws := WideString(s);
  len := WideCharToMultiByte(CP_UTF8, 0, PWideChar(ws), -1,
    Nil, 0, Nil, Nil);
  SetLength(Result, len+1);
  WideCharToMultiByte(CP_UTF8, 0, PWideChar(ws), -1,
    PChar(Result), len, Nil, Nil);
  Result := PChar(Result);
end;

RFC3339形式(2005-12-17T03:11:13.867+09:00)でTDateTimeをダンプ

uses Windows, DateUtils, StrUtils;
function LocalDateTimeToInternetDateTime(t: TDateTime): String;
var
  offset: TDateTime;
  TZI: TTimeZoneInformation;
begin
  offset := 0;
  case GetTimeZoneInformation(TZI) of
    TIME_ZONE_ID_STANDARD: offset := (TZI.Bias + TZI.StandardBias) / 1440;
    TIME_ZONE_ID_DAYLIGHT: offset := (TZI.Bias + TZI.DaylightBias) / 1440;
    TIME_ZONE_ID_UNKNOWN: offset := TZI.Bias / 1440;
  else
    //RaiseLastWin32Error;
  end;
  t := t+offset;
  offset := -offset;
  Result := FormatDateTime('yyyy-mm-dd', t) + 'T' + 
    FormatDateTime('hh:nn:ss.zzz', t);
  if (Abs(offset) >= 1/1440) then begin
    Result := Result+IfThen(offset>0, '+', '-')
      +Format('%.2d:%.2d', [HourOf(offset), MinuteOf(offset)]);
  end else begin
    Result := Result+'Z';
  end;
end;