First, when you open your destination file you need to open it for writing. Without a second parameter fopen will open for read access. If your destination file did not exist it would return you a -1 file handle.
Use instead:
fopen(filename2,'w')
Here is a simplified version of your code including that amendment:
filename = 'c:\try.csv';
fid_in = fopen(filename,'r'); %Access file with empty data blocks
filename2 = 'C:\try_corrected.csv';
fid_out = fopen(filename2,'w'); %Access destination file
while (~feof(fid_in))
str=fgets(fid_in);
if (~doublecommas(str))
fprintf(fid_out,'%s',str);
end
end
fclose(fid_in);
fclose(fid_out);
type(filename2)
This uses a different method to detect double presence of commas in the CSV line:
function flag=doublecommas(str)
flag=false; % flag = result returned,
% true if empty CSV fields present in line
if (ischar(str) && length(str)>0)
for cindex=1:length(str)-1
if strcmp(str(cindex:(cindex+1)),',,')
flag=true; break;
end
end
end
return;