从字符串中取数字

function GetNumFromStr(const str: String;const hex:boolean=false): String;
var
i:integer;
charset:Set of char;
begin
if hex then
charset:=['0'..'9','a'..'f','A'..'F','.']
else
charset:=['0'..'9','.'];
for i := 1 to Length(str) do
 begin
   if (str[i] in charset) then
     result:= result + uppercase(str[i]);
 end;
end;