CODEWITHSUNDEEP
matlab
user1365673
user1365673

Reputation: 27

fprintf prints random string letters (i.e. K or á) between numbers

I am having a trouble with fprintf and I would so much appreaciate if you could help me:
In the programme on which I am working now, I am tracking the mouse position when the mouse is clicked using get(gca, ‘currentpoint’) and then I save the final position using fprintf. Everything works smoothly when I do not define a particular axis position in the figure window; however when I use set(gca, ‘visible’, ‘off’, ‘position’, []) command to define a particular axis position, fprintf sometimes writes down a string, either K or á, on the text file, which then gives the obvious error for dlmread when the file is tried to be read. I wonder what might be the cause of those strings on the text file.

Here's the code:

mouse = get(gca, 'currentpoint');
A = mouse(1, 1);
B = mouse(1, 2);
save x_center4.txt A -ascii;
save y_center4.txt B -ascii;
A = load('C:\MATLAB6p5\work\x_center4.txt');
B = load('C:\MATLAB6p5\work\y_center4.txt');
fid = fopen('grand_xcenter4.txt', 'a');
fid2 = fopen('grand_ycenter4.txt', 'a');
fprintf(fid, '%s %d\n', A);
fprintf(fid2, '%s %d\n', B);
fclose(fid);
fclose(fid2);

Upvotes: 0

Views: 1514

Answers (1)

tmpearce
tmpearce

Reputation: 12693

fprintf(fid, '%s %d\n', A);
fprintf(fid2, '%s %d\n', B);

You are providing only 1 argument after the format string, when the format string specifies two arguments: a string (%s) and a base 10 signed integer (%d)?

This is most likely the cause of the strange characters you are reporting. It may help to know what the type and value of A and B are before the fprintf calls.

I've been looking for official documentation of what constitutes "Undefined Behavior" in MATLAB, but have yet to find a good source. However, failing to provide the right number and type of arguments that the string specifies almost certainly qualifies.

Upvotes: 2

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