MATLAB: I want to select one column of an array at a time every time a for loop starts

Question

A=[1 2 3, 4 5 6, 7 8 9,……,n]

so i want the first loop to work with the first column of A to do an operation, then the second loop the same operation but with the second column of A and so on

Answer 1

A = rand(3) ;
for i = 1:3
A(:,i)
end