MATLAB: How to judge some bytes is or not a-z,A-Z

chars

i read some files using fread ,then some bytes display like blank , but there is sth.,i want to delete these special chars ,how to make it ? thanks

Roger, use regular expressions, something like

 str = 'a b{}c1230O /&" â'
 str =
 a b{}c1230O /&" â
 str_rep = regexprep(str,'[^a-zA-Z0-9]','')
 str_rep =
 abc1230O

You could perform the load in a try/catch block and react accordingly:

 try
     load(filename);
 catch e
    % Something went wrong -- not a valid file to load?
 end

perhaps you means an element-wise multiplication?

z = x.*y;

what you're doing above is a matrix multiplication from linear algebra.