Lazarus function to find 8 digit numbers in a string

Question

I have e-mail subject lines and I want to find ticket references in them it could be the TT ref is like 12345678. One subject line (string) can have multiple 8 digit numbers!

I have been using the below code but it is merely stripping out the first 8 digits then doing a check if that is 8 char long:

function StripNumbers(const aString: string): string;
var
  C: char;
begin
  Result := '';
  for C in aString do
  begin
    if CharInSet(C, ['0'..'9']) then
    begin
      Result := Result + C;
    end;
  end;
end;   

Example:

my string variable is

subject := "yada yada XF12345678 blabla XF87654321 duh XF11.223344"

function GetTTRefs(subject) should result "12345678;87654321;"

Thank you for answers.

Answer 1

function GotTTRefs(Subject:string;Digits:Byte):string;
var
  i:integer;
  TT:string;
begin
   i:=1;
   while i <= Length(Subject)-Digits+1 do
   begin
     if Subject[i] in ['1'..'9'] then
        begin
          TT:=Copy(Subject,i,Digits);
          if (StrToQWordDef(TT, 0) <> 0) then
              Result:=Result+TT+';';
        end;
     inc(i);
   end;
end;