// Объявления

function RAROpenArchive(ArchiveData : Pointer): Integer; stdcall;
external 'unrar.dll' name 'RAROpenArchive';

function RARCloseArchive(hArcData : Integer): Integer; stdcall;
external 'unrar.dll' name 'RARCloseArchive';

function RARReadHeader(hArcData : Integer; HeaderData : Pointer):
Integer; stdcall;
external 'unrar.dll' name 'RARReadHeader';

function RARProcessFile(hArcData : Integer; Operation : Integer;
DestPath : Pointer; DestName : Pointer): Integer; stdcall;
external 'unrar.dll' name 'RARProcessFile';


const
 ERAR_END_ARCHIVE = 10;
 ERAR_NO_MEMORY = 11;
 ERAR_BAD_DATA = 12;
 ERAR_BAD_ARCHIVE = 13;
 ERAR_UNKNOWN_FORMAT = 14;
 ERAR_EOPEN = 15;
 ERAR_ECREATE = 16;
 ERAR_ECLOSE = 17;
 ERAR_EREAD = 18;
 ERAR_EWRITE = 19;
 ERAR_SMALL_BUF = 20;

 RAR_OM_LIST = 0;
 RAR_OM_EXTRACT = 1;
 RAR_SKIP = 0;
 RAR_TEST = 1;
 RAR_EXTRACT = 2;
 RAR_VOL_ASK = 0;
 RAR_VOL_NOTIFY = 1;

type
 Char260 = array [1..260] of Char;

 TRAROpenArchiveData = record
 ArcName : PChar; // в C++ это будет выглядеть как: char *ArcName
 OpenMode : Cardinal;
 OpenResult : Cardinal;
 CmtBuf : PChar;
 CmtBufSize : Cardinal;
 CmtSize : Cardinal;
 CmtState : Cardinal;
 end;

 TRARHeaderData = record
 ArcName : Char260;
 FileName : Char260;
 Flags : Cardinal;
 PackSize : Cardinal;
 UnpSize : Cardinal;
 HostOS : Cardinal;
 FileCRC : Cardinal;
 FileTime : Cardinal;
 UnpVer : Cardinal;
 Method : Cardinal;
 FileAttr : Cardinal;
 CmtBuf : PChar;
 CmtBufSize : Cardinal;
 CmtSize : Cardinal;
 CmtState : Cardinal;
 end;


var
 RARExtract : boolean;
 RAROpenArchiveData : TRAROpenArchiveData;
 RARComment : array [1..256] of Char;
 RARHeaderData : TRARHeaderData;

...

procedure ExtractRARArchive;
var
 sDir : string;
 s : string;
 sTest : string;
 iTest : integer;
 bTestDone : boolean;
 RARhnd : Integer;
 RARrc : Integer;
 PDestPath : Char260;
begin
 RARExtract:=TRUE;
 lKBWritten:=0;
 ProgressBar2.Position := 0;
 ProgressBar2.Max := lTotalSize;
 RARStartTime:=Time;

 RAROpenArchiveData.OpenResult:=99;
 RAROpenArchiveData.OpenMode := RAR_OM_EXTRACT; // открываем для распаковки
 RAROpenArchiveData.ArcName:= @RARFileName;
 RAROpenArchiveData.CmtBuf := @RARComment;
 RAROpenArchiveData.CmtBufSize := 255;

 // Открываем RAR архив и выделяем память
 RARhnd := RAROpenArchive (@RAROpenArchiveData);
 if RAROpenArchiveData.OpenResult <> 0 then
 begin
 case RAROpenArchiveData.OpenResult of
 ERAR_NO_MEMORY : s:='Not enough memory to initialize data structures';
 ERAR_BAD_DATA : s:='Archive header broken';
 ERAR_BAD_ARCHIVE : s:='File is not valid RAR archive';
 ERAR_EOPEN : s:='File open error';
 end;
 MessageDlg('Unable to open rar archive: ' + s + '!',mtError, [mbOK], 0);
 end;

 RARSetProcessDataProc(RARhnd,@Form.OnRarStatus);
 StrPCopy(@PDestPath, EInstallPath.Text);

 repeat
 RARrc := RARReadHeader (RARhnd, @RARHeaderData);// Читаем заголовок
 if RARrc <> ERAR_END_ARCHIVE then
 begin
 ProgressBar1.Position := 0;
 ProgressBar1.Max := RARHeaderData.UnpSize;
 s:=RARHeaderData.FileName;
 lblCurrentFile.Caption := s;
 lKBytesDone := 0;
 end;

 if RARrc = 0 then
 RARrc:=RARProcessFile (RARhnd, RAR_EXTRACT, @PDestPath, nil);
 if (RARrc <> 0) and (RARrc <> ERAR_END_ARCHIVE) then
 begin
 MessageDlg('An Error occured during extracting of ' + sTest+'!' + #13#10 +
 'RARProcessFile: ' + MakeItAString(RARrc),mtError, [mbOK], 0);
 end;
 until
 RARrc <> 0;

 // закрываем RAR архив и освобождаем память
 if RARCloseArchive(RARhnd) <> 0 then
 begin
 MessageDlg('Unable to close rar archive!',mtError, [mbOK], 0);
 end;
end;