how to use iteration variable in variable name - Matlab [duplicate]

Question

I have a struct res with the variables: det1, det2, det3. I also have the amount of these variables (in this case 3), and I want to read them in a loop. How can I integrate the iteration variable in the name of the variables in the loop and read them? I want to do something like this:

for i=1:num_variables
    var_name = 'res.det'+num2str(i);
    % read var_name
end 

Thanks for the help!