Having trouble with a question using arrays

The questions is:

Use the function checkupc to classify and print the total number of UPC entries stored in the array codes that are valid, invalid or missing digits. Delete all rows from the array codes that have an invalid UPC or missed digits.

The code for checkupc is:

    function check = checkupc(upc)
    [m n] = size(upc);
    if m == 1 && n == 12
        y = mod(sum([upc(2) upc(4) upc(6) upc(8) upc(10) upc(12)])+3*sum([upc(1) upc(3) upc(5) upc(7) upc(9) upc(11)]),10)
    if y == 0
        check = 1
    else
        check = 0
    end

    else c = 12-n check = -c end

The question beforehand asked:

The file upcs.txt contains a list of UPC codes that were scanned in a grocery store. Each line should, ideally, contain 12 digits corresponding to a single product. Read the contents of the file and store the entries into an m x 12 sized numeric array named codes, where m is the number of valid lines in the le. Lines that have less or more than 12 digits should be discarded. Some lines with 12 digits may have digits that were not correctly scanned, which were replaced by the letter X'. These missing digits should be represented in the array codes by the integer-1'. After processing the file, print the total number of lines read, the number of lines discarded, and the number of lines correctly processed and stored in codes.

upcs.txt:

X9096X082489

921642004330

810905023006

733554287763

413527622XX1

287X35871528

100093334850

764491079X90

1537X8886614

086755751640

860053705316

980098819206

038356338621

577577248178

82825685985

684580785580

736657539753

71113617151

935014271064

702345843488

58316491755

110118383664

333841856254

996003013296

495258095746

4457870230

684104168936

522784039910

6504512835

699553963094

853110488363

554147120089

The code for the problem above is:

C = textscan(fid,'%s');
C = C{1};

all_codes_num = size(C,1);
codes_discarded_num = 0;
codes_missed_digit_num = 0;
codes_correct_num = 0;
codes = [];
for i = 1:all_codes_num
one_code = C{i};
if length(one_code) == 12
    x_flag = 0;
    code_tmp = zeros(1,12);
    for j = 1:12
        if one_code(j) == 'X' || one_code(j) == 'x'
            code_tmp(j) = -1;
            x_flag = 1;
        else 
            code_tmp(j) = str2num(one_code(j));
        end
    end
    if x_flag == 1
        codes_missed_digit_num = codes_missed_digit_num +1;
    end
    codes = [codes;code_tmp];
elseif length(one_code) ~= 12
    codes_discarded_num = codes_discarded_num + 1;
end
end

all_codes_num
codes_discarded_num
codes_with_x = codes_missed_digit_num
correct_codes_without_x = all_codes_num - codes_discarded_num - codes_with_x

[Walter Roberson]

duplicates http://www.mathworks.co.uk/matlabcentral/answers/67245-having-trouble-with-this-problem