Ignoring comments in lines when parsing

I am parsing a file with the following code:

C = textscan(fid,fmt,opt{:},'CommentStyle','#'); 

This works in ignoring comments that begin a line such as this:

apple = 12
#mycomment

but how do I ignore comments that are in a line.

For example, I want to be able to parse the following line:

apple = 12 #mycomment

Currently, the comment will not be ignored. Within my current scheme, how do I ignore this? Thanks!

Answer 1

[Adam Danz]

I think you'll have to clean up the text after you've imported it.

Use regexp() to find the location of '#' in each element of C. Then trim everything from that index onward, for each element of C.

% Example text
C = {'pi = 3.14159'; 'apple = 12 #my comment'; 'banana = 13 #one #two comments'; 'orange = 6'; 
    'grapes = 8 #comment'}; 

% Find first location of '#' in each element
indices = regexp(C, '#', 'Once'); 
% remove those sections (and any leading/trailing white space)
trimmedTxt = cellfun(@(x,y)strtrim(x(1:y-1)), C, indices, 'UniformOutput', false); 
% Add in the elements of C that didn't have any '#' characters
trimmedTxt(cellfun(@isempty,trimmedTxt)) = C(cellfun(@isempty,trimmedTxt)); 

Result

trimmedTxt =
  5×1 cell array
    {'pi = 3.14159'}
    {'apple = 12'  }
    {'banana = 13' }
    {'orange = 6'  }
    {'grapes = 8'  }

Answer 2

[Walter Roberson]

S = fileread(TheFileName);
S = regexprep(S, '#.*$', '', 'dotexceptnewline');
C = textscan(S, fmt);

This fails if there can be a # inside a string, or if there is a syntax for "escaping" # so they are not comment symbols, such as \#

apple = 12
peptalk = Apple, we are you #1 fans!