use the function
* struct2cell()
* cell2mat()


------------------- Test Code -------------------------
function demo_structArray()
    % create a struct array
    NUM = 10;
    a = struct('name',cell(NUM,1),'val',1); % a 10-by-1 struct array with 2 field
    
    % we want to get the  a(:).val as an array
    a_cell = struct2cell(a); % a_cell is a 2-by-10 cell array
    b = a_cell(2,:);     
    b = cell2mat(b);
    b
end

----------------- Results ---------------

b =

     1     1     1     1     1     1     1     1     1     1
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