I need to take the difference of length of NUM1 and ANS and Num2 & ANS and append zero equal to the difference of length to both NUM1 and NUM2. I have trouble doing that.
sum(NUM1, NUM2, ANS):-
comp(NUM1, ANS),
comp(NUM2, ANS),
% Arguments: Carry's from right and to left both 0 and all available digits
add( NUM1, NUM2, ANS, 0, 0, [0,1,2,3,4,5,6,7,8,9], _).
add( [], [], [], C, C, Digits, Digits).
comp(NUM, ANS).
comp(NUM, ANS, OUT):-
length(NUM, L1),
length(ANS, L2),
LI = [0],
(L1 < L2 -> OUT = appendlist(LI, NUM, NUM)).
appendlist([],X,X).
appendlist([X|Y],Z,[X|W]) :- append(Y,Z,W).
