Help required for timeframe get price

Plug-ins
#1 
DH=TimeFrameGetPrice("H",inDaily,-1);
DL=TimeFrameGetPrice("L",inDaily,-1);
mycalc=(DayH-DayL);

TimeFrameGetPrice returns an array.

  1. How many values are there in the array DH and DL?
  2. How to subtract DH-DL in C++ (creating DLL) ?
    How AFL subtract these two arrays? Each value in the array is subtracted and stored in the resulting array?
    Result of the subtraction is an array or a single value?
    Thanks
#2
  1. See http://www.amibroker.com/guide/h_timeframe.html (read ALL the orange boxes) and How do I debug my formula?
  2. See 5 reasons why you should NOT write DLLs
#3