Why isnt this matlab code working? - matlab

Question

I'm trying to write a script to remove comment lines from another script file. Here's what I tried:
fid = fopen('correct_answer.m');
aline = {};
counter = 1;
while ~feof(fid)
aline{counter} = fgetl(fid);
if aline{counter}(1) == '%'
aline{counter} = '';
end
counter = counter + 1;
end
This is the error I get:
Attempted to access aline.%cell(1); index out of bounds because numel(aline.%cell)=0.
Error in hw2 (line 8)
if aline{counter}(1) == '%'
If I run it without the while loop it works fine. What's up with this??
Also if you just happen to know a more simple/efficient approach to removing comment lines that would work too ;)

Answer 1

The problem is that you sometimes read empty lines, and you cannot access the first element of empty lines. Additionally you may have comments at the end of a valid line of code, this code should do the trick
fid = fopen('correct_answer.m');
aline = {};
counter = 1;
while ~feof(fid)
aline{counter} = fgetl(fid);
if ~isempty(aline{counter})
k = strfind(aline{counter}, '%');
aline{counter}(k:end) = '';
end
counter = counter + 1;
end