How to force a for loop to continue?

Hi, I need to copy data from individual excel files from 33 participants, and paste all in one excel file. I did it for the first sheet and then for the second sheet, etc. The problem is that some of the files have 4 sheets and some have 6 sheets. Also, some of the sheets do not have data. Therefore the script stops when there is no data. How can I force it to continue and report the missing data? The following stops when data doesn't exist.

       first_data = true;

        for i=2:34   
           sheet=6;
           STIMroot='C:\Users\ski\CloudStation\Zahra\dissertation\data analysis\behavioral data analysis\monolingualSTIM\';
           Drop='C:\Users\ski\CloudStation\Zahra\dissertation\data analysis\behavioral data analysis\monolingualSTIM\final.xls';

            STIMfile=strcat(STIMroot,num2str(i),'\',num2str(i),'.xls');    %get the STIM file

            if exist(STIMfile,'file')
               STIMdata = xlsread( STIMfile,sheet);
               data2=STIMdata(:,3:5);

                 if first_data == true;
                         export_data = data2; 
                         first_data = false;
                      else
                          export_data =  horzcat(export_data,data2 );

                      end
            else
                warningMessage = sprintf('Warning: file does not exist:\n%s',h);
                 continue;
            end
            end
               xlswrite(Drop,export_data,1);

Answer 1

[OCDER]

https://www.mathworks.com/help/matlab/ref/try.html

Use try/catch statements to force a loop to continue due to an unexpected error.

for j = 1:10
   try
      ... your code...
   catch
      warning('found error in %dth file', j);
      continue
   end
   ... your code, if "try" codes succeed
end

[Elaheh]

Thank you. What do you mean by this part?

... your code, if "try" codes succeed

[OCDER]

Oh, I just meant that you can use try/catch flexibly to do different things for different function errors.

%EXAMPLE 1
try 
   doThis %Try this, if it fails, no fatal error
catch
   continue
end
doThis2; %doThis succeeded, but if doThis2 errors, make it a fatal error.

%EXAMPLE 2
try 
   doThis   %Try this, if it fails, no fatal error
   doThis2; %If this errors, it's no longer a fatal error.  
catch
   continue
end

[Jan]

Some programmers avoid continue for reasons of clarity. The code can be written without it also:

for j = 1:10
   try
      ... your code...
      ... your code, if "try" codes succeed
   catch ME
      warning('found error in %dth file: %s', j, ME.message);
   end   
end