Iterating over a list of strings in MATLAB

str={'aaa','bbb'};
fprintf('%s\n',str{:});

No need for for loops.

EDIT: See also: cellfun

You should call the cell's content via str{1} as follows to make it correct:

for str = {'aaa','bbb'}
  fprintf('%s\n',str{1});
end

Here's a more sophisticated example on printing contents of cell arrays.

Starting with R2016b you can use string arrays:

for str = ["aaa" "bbb"]
  fprintf('%s\n',str);
end