Go back inside a for loop

Hello everyone, I have created this function to show multiple dicom images and select one of them:

for z=1:size(read)
  archive = read(z).name;
  R3 = (dicomread(archive));
  imshow(R3);
  set(gcf, 'units','normalized','outerposition',[0 0 1 1]);     
  promptMessage = sprintf('Select the first image\nmanually');
  titleBarCaption = 'Manual';
  button = questdlg(promptMessage, titleBarCaption, ...
                   'Next', 'Select', 'Previous', 'Next');
  if strcmpi(button, 'Previous')
     ¿¿??
  end
  if strcmpi(button, 'Select')
    %I execute the code
  end
end

My question is: how could I go back to the previous image when I push the "Previous" button without to break the for loop? What should I modify?

Thank you so much.

Answer 1

[Walter Roberson]

   z = 1;
   while z <= length(read)
    archive = read(z).name;
    R3 = (dicomread(archive));
    imshow(R3);
    set(gcf, 'units','normalized','outerposition',[0 0 1 1]);     
    promptMessage = sprintf('Select the first image\nmanually');
    titleBarCaption = 'Manual';
    button = questdlg(promptMessage, titleBarCaption, ...
                     'Next', 'Select', 'Previous', 'Next');
    if strcmpi(button, 'Previous')
       z = z - 1;
       continue;
    end
    if strcmpi(button, 'Next')
      z = z + 1;
      continue;
    end
    if strcmpi(button, 'Select')
      %I execute the code
      ....
      break;   %leave while loop
    end
  end

[Image Analyst]

read() is the name of a built-in function so he probably doesn't want to use that.

[Jose Andrés]

It works perfectly! Thank you so much again, you are amazing.

The real directory name is called "lee_archivos" because I'm spanish, and I had to change some names (like 'Next', 'Previous'...) here in my Question in order to make it clearer for everyone. Thank you anyway!