Function sExtractBetweenTagsB(Const s, LastTag, FirstTag: string): string;

var

  pLast,pFirst,pNextFirst : Integer;

begin

  pFirst := Pos(FirstTag,s);

  pLast := Pos(LastTag,s);

  while (pLast > 0) and (pFirst > 0) do begin

    if (pFirst > pLast) then // Find next LastTag

      pLast := PosEx(LastTag,s,pLast+Length(LastTag))

    else

    begin

      pNextFirst := PosEx(FirstTag,s,pFirst+Length(FirstTag));

      if (pNextFirst = 0) or (pNextFirst > pLast) then begin

        Result := Copy(s,pFirst,pLast-pFirst+Length(LastTag));

        Exit;

      end

      else

        pFirst := pNextFirst;

    end;

  end;

  Result := '';

end;

var

  s: String;

begin

  s := 'Delphi App Hello Hello SomeText here Hello Hello Hello This is a Test! Hello';

  WriteLn(sExtractBetweenTagsB(s,'Test','Hello'));

end.

输出:

Hello This is a Test

来源：https://stackoverflow.com/questions/30827180/delphi-extract-string-between-tags-duplicate-tags