title: how to take combined string and num as filename in Matlab
body: <p>I want to use a combined string and num as a file name, like that:</p>
  
  <pre><code>for im_num = 1:10
      im_name = sprintf('bottle crate/bottle_crate_%d.png',im_num); 
      file_num =  sprintf('f%d',im_num); 
      file_num = imread(im_name);
  end
  </code></pre>
  
  <p>I can use combined string as file path, but the filename, I want to change from f1, f2 to f10 but it didn't work, how to change it?</p>