Undeclared identifier: 'PosEx'

I tried to use this code in my program in delphi 2007

function ExtractText(const Str: string; const Delim1, Delim2: string): string;
var
  pos1, pos2: integer;
begin
  result := '';
  pos1 := Pos(Delim1, Str);
  if pos1 > 0 then begin
    pos2 := PosEx(Delim2, Str, pos1+1);
    if pos2 > 0 then
 开发者_开发知识库     result := Copy(Str, pos1 + 1, pos2 - pos1 - 1);
  end;
end;  

I did a search on google i've found that i need "FastCode.Libraries-0.6.4.zip" i download it but don't know how to use it to make the code above works. please help!

PosEx is defined in the StrUtils unit. Make sure to include it in your uses clause.