Add an element to a 3D array

I want to add to a 3D array using a for loop without changing the previous values. I created an empty 3D array by writing:

Array= zeros(0,0,100);

Then i wrote a for loop to append to that array the index number of when the if statement is satisfied, in the correct 3rd dimension

 for 3Dimages=1:100
    for i=1:512*inputofuser
        if Original3Dimage(i,:,3Dimages)==0
            Array=[Array(:,:,3Dimages),i];           
        else
            break
            
            
        end
        
    end
    end

I know if this was 2D, it could be done by saying Array=[Array,i] but i want this to be done in 3D such that depending on which of the 1:100 3Dimages the for loop is in, it creates a row of i values in the same 1:100 3Dimages page of the Array.

Example:

when 3Dimages=1

lets say the true statement occurs at an i value of 1,2,3,4,5

then when 3Dimages=2, the true statement occurs at an i value of 6,7

then when 3Dimages=3, the true statement occurs at an i value of 10,11,12

therfore Array in this 3Dimages=1:3 smaller example would have a size of 1 5 3 where:

(:,:,1)= [1 2 3 4 5]

(:,:,2)= [6 7 blank blank blank]

(:,:,3)= [10 11 12 blank blank]

Answer 1

[Jos (10584)]

To concatenate two arrays A and B in the third dimension, use cat

cat(3, A, B)

Note that all the other dimensions of A and B should match (which does not seem to be the case in your example, at first sight). And, by the way:

% [A ; B] <-> cat(1, A, B)
% [A B] <-> cat (2, A, B)