function TForm1.ExtractString(const aString: string; const aSeparator: char; var aPos: Integer): string;
var
  I: Integer;
begin
  I := aPos;
  while (I <= Length(aString)) and (aString[I] <> aSeparator) do Inc(I);
  Result := Trim(Copy(aString, aPos, I - aPos));
  if (I <= Length(aString)) and (aString[I] = aSeparator) then Inc(I);
  aPos := I;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
  lString, lSubString: string;
  lPos, j: integer;
begin
  lString := '023842394201342|343242423423|342342424|533423|2455';
  lPos := 1;
  j := 0;
  while lPos <= Length(lString) do
  begin
    lSubString := ExtractString(lString, '|', lPos);
    inc(j);
    if j = 2 then    // 第二個
      showmessage(lSubString);
  end;
end;