Question

I have number as String.
How to convert that string to LongWord?

I know how to convert it to integer. But integer is to small for me.

Answer 1

Actually you can use StrToInt.

The resulting value will overflow (i.e. become negative for values above $7fffffff, you might want to disable overflow checking), but when it is casted to longword, you will get the correct value.

Although the low level Val might be safer:

var
  x: longword;
  e: word;
begin
  Val('$9fffffff', x, e);

  writeln(x);
end.