Error when try to process many file

i try process many file but at the middle, error like below:

Error using ==> fprintf Invalid file identifier. Use fopen to generate a valid file identifier.

Error in ==> Final at 19

??? C:\Program Files\MATLAB\R2010a\toolbox\matlab\codetools\opentoline.m: Too many files open; check that FILES = 20 in your CONFIG.SYS file.

what meants and how to solve?? need help

Answer 1

[Walter Roberson]

Usually it means that you have forgotten to fclose() your files.

There have been reports at various times of running in to this problem when using some of the utility routines along the lines of xlswrite(), routines that should be closing files but sometimes do not.

I do not recall hearing of this problem with regards to codetools, but I have not read much about that product.

[Jan]

To get a list of open file: fopen('all')