Here is the code:
file_name = 'test';
eval(['file_length = length(who(''-file'',' file_name '));']);
But this doesn't work, because who requires a quoted string as a variable. Then I tried this,
eval(['file_length = length(who(''-file'', ''file_name'' ));']);
It didn't work, apparently. Now file_name showed up instead of the value I put in it. This sounds a very simple question, but I just don't know what to do. Help!