Get integer portion of string in Pascal

Question

I have a string Alpha 2 from which I need to extract the integer portion i.e. 2.

This is a quick and dirty project and I'm not currently interested in learning Pascal. All I need is a quick answer!

Answer 1

var
  sub: string;
  i: Integer;
begin
  sub := Copy('Alpha 2', 7, 1);
  i := StrToInt(sub);

-

const
  str = 'Alpha 2';
var
  i: Integer;
begin
  i := StrToInt(str[7]);

-

var
  str: string;
  sub: string;
  spc: Integer;
  i: Integer;
begin
  str := 'Alpha 257';
  spc := Pos(' ', str);
  sub := Copy(str, spc + 1, Length(str) - spc);
  i := StrToInt(sub);

There's also StrToIntDef if you don't want an exception to be raised when the argument is not an integer.

Answer 2

For a method that searches the first number in a string and returns it as an integer, use the following code. It will either return a positive integer value or -1 if no number was found in the string.

function IntegerInString(s: string) : integer;
var i, state, startPos, endPos : integer;
begin
  state := 0;
  startPos := -1;
  endPos := Length(s);
  for i := 1 to Length(s) do
  begin
    if ((s[i] >= '0') and (s[i] <= '9') then
    begin
      if state = 0 then startPos := i;
      state := 1;
    end else
      if state = 1 then
      begin
        endPos := i;
        break;
      end;
    end;
  end;
  if startPos > -1 then
    result := IntToStr(Copy(s, startPos, endPos))
  else
    result := -1;
end;