How to best print output to command window during a loop in Matlab?

Check the fprintf. You can format your output just like you want.

for id=1:num_ids
    % do something
    if isempty(stress_value)
        fprintf('The following ID does not have an assigned stress value: %d\n',id)
        continue
    end
    % do something
end

The error function will stop code execution.

The display function only prints the value of the variable, without printing the variable name.