The magic message is "Too many open files". You forgot to close the files after accessing them. But the operating system can keep a limited list of open files only.
Some comments to your code:
- The large number of global variables is critical. I recommend to avoid globals in general. But this does not matter your problem here.
- myslash is easier created by the builtin function filesep.
- for j = 1 ?! Simply omit a loop, which runs once only.
- eval (['[' answer{1} ']']) is cruel. But it does not concern your problem here.
- In the subfunction cb the file is not closed, if get(h, 'Value') == lastVal. Better move the fclose(fid) to the end of the subfunction. <== This matters
A helpful strategy: Always use fclose in the same function and indentation level than fopen. Never return from the function in between, e.g. by return or error. In case of doubts use onCleanup to close the file. Always check fid==-1 after fopen.
To see a list of open files:
fopen('all')
