MATLAB: Delete lines from text file

Question

How can I delete all the lines form a text file after the line number x and store it in another test file?

Answer 1

As shown in the help:

fid = fopen('fgetl.m');
tline = fgetl(fid);
while ischar(tline)
    disp(tline)
    tline = fgetl(fid);
end
fclose(fid);

Now just modify that to open 2 files, and add a line counter then break after you've transferred x of them (untested)

fin = fopen('input.txt');
fout = fopen('output.txt', 'wt');
tline = fgetl(fin);
count = 0;
while ischar(tline) && count < x
    disp(tline)
    tline = fgetl(fin);
    if ischar(tline)
        fprintf(fout, '%s\n', tline);
    end
    count = count + 1;
end
fclose(fin);
fclose(fout);