Code:

uses

{$IFDEF WIN32}

Registry; {We will get it from the registry}

{$ELSE}

IniFiles; {We will get it from the win.ini file}

{$ENDIF}

{$IFNDEF WIN32}

const

MAX_PATH = 144;

{$ENDIF}

function GetProgramAssociation(Ext: string): string;

var

{$IFDEF WIN32}

reg: TRegistry;

s: string;

{$ELSE}

WinIni: TIniFile;

WinIniFileName: array[0..MAX_PATH] of char;

s: string;

{$ENDIF}

begin

{$IFDEF WIN32}

s := '';

reg := TRegistry.Create;

reg.RootKey := HKEY_CLASSES_ROOT;

if reg.OpenKey('.' + ext + '\shell\open\command',

   false) <> false then

begin

   {The open command has been found}

   s := reg.ReadString('');

   reg.CloseKey;

end

else

begin

   {perhaps thier is a system file pointer}

   if reg.OpenKey('.' + ext,

     false) <> false then

   begin

     s := reg.ReadString('');

     reg.CloseKey;

     if s <> '' then

     begin

       {A system file pointer was found}

       if reg.OpenKey(s + '\shell\open\command',

         false) <> false then

         {The open command has been found}

         s := reg.ReadString('');

       reg.CloseKey;

     end;

   end;

end;

{Delete any command line, quotes and spaces}

if Pos('%', s) > 0 then

   Delete(s, Pos('%', s), length(s));

if ((length(s) > 0) and

   (s[1] = '"')) then

   Delete(s, 1, 1);

if ((length(s) > 0) and

   (s[length(s)] = '"')) then

   Delete(s, Length(s), 1);

while ((length(s) > 0) and

   ((s[length(s)] = #32) or

   (s[length(s)] = '"'))) do

   Delete(s, Length(s), 1);

{$ELSE}

GetWindowsDirectory(WinIniFileName, sizeof(WinIniFileName));

StrCat(WinIniFileName, '\win.ini');

WinIni := TIniFile.Create(WinIniFileName);

s := WinIni.ReadString('Extensions',

   ext,

   '');

WinIni.Free;

{Delete any command line}

if Pos(' ^', s) > 0 then

   Delete(s, Pos(' ^', s), length(s));

{$ENDIF}

result := s;

end;

procedure TForm1.Button1Click(Sender: TObject);

begin

ShowMessage(GetProgramAssociation('gif'));

end;