Cancel a program in MATLAB

I have this code:

fileName = inputdlg('Please enter the name for your figures');
directoryName = uigetdir('','Please select a folder to save to');
if directoryName == 0      %# User pressed the "Cancel" button...
directoryName = '';      %#   ...so choose the empty string for the folder
end
filePath = fullfile(directoryName,fileName{1});  %# Create the file path
extensions = {'fig','bmp'};
for k = 1:length(extensions)
  saveas(gcf,filePath,extensions{k});  %# Sa开发者_开发技巧ve the file
  set(gcf,'PaperPositionMode','auto');
end

It has some problem. When I run it, this error occurs:

??? Index exceeds matrix dimensions.

Error in ==> fyp_editor>uipushtool9_ClickedCallback at 1607

filePath = fullfile(directoryName,fileName{1}); %# Create the file path.

And another thing is when i pressed the cancel button, it kkeep going to filepath. How I want to do something like; when I push Cancel, then it will cancel the save program.

If the user presses Cancel fileName will be empty ( 0x0 cell array). fileName{1} is what causes the exception