/// <summary>
/// Enumerates all installed Common Language Runtime Engines.
/// </summary>
/// <param name="Index">Zero-based index of looked runtime
///record.</param>
/// <returns>True if runtime with specified index found.</returns>
function EnumInstalledRuntimes(Index: Integer; out VersionName: String):
Boolean;
var
 hkey: Windows.HKEY;
 hsubkey: Windows.HKEY;
 I: Cardinal;
 J: Cardinal;
 NameBuf: array[0..MAX_PATH] of Char;
 CNameBuf: Cardinal;
 lwt: TFileTime;
 vt: DWORD;
 AnyFound: Boolean;
begin
 Result := False;
 VersionName := '';
 if ERROR_SUCCESS = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
 PChar('SOFTWARE\Microsoft\.NETFramework\policy'), 0,
 KEY_ENUMERATE_SUB_KEYS, hkey) then
 try
  I := 0;
  while True do
  begin
  AnyFound := False;
  CNameBuf := MAX_PATH + 1;
  if ERROR_SUCCESS <> RegEnumKeyEx(hkey, I, @NameBuf[0], CNameBuf,nil, nil, nil, @lwt) then
  begin
  Break;
  end;
  if (NameBuf[0] = 'v') and (NameBuf[1] in ['1'..'9']) then
  begin
  VersionName := String(NameBuf);
  if ERROR_SUCCESS = RegOpenKeyEx(hkey, @NameBuf[0], 0,KEY_QUERY_VALUE, hsubkey) then
  try
  J := 0;
  while true do
  begin
  CNameBuf := MAX_PATH + 1;
  if ERROR_SUCCESS <> RegEnumValue(hsubkey, J, @NameBuf[0],CNameBuf, nil, @vt, nil, nil) then
  begin
  Break;
  end;
  if (vt = REG_SZ) and (NameBuf[0] <> #0) then
  begin
  VersionName := VersionName + '.' + String(NameBuf);
  AnyFound := True;
  Break;
  end;
  Inc(J);
  end;
  finally
  RegCloseKey(hsubkey);
  end;
  end;
  Inc(I);
  if AnyFound then
  begin
  if Index = 0 then
  begin
  Result := True;
  Break;
  end;
  Dec(Index);
  end;
  end;
 finally
  RegCloseKey(hkey);
 end;
end;