even after using fopen, still giving negative fid. how to get a valid fid?

clc;

clear;

close all;

filename = fullfile(matlabroot,'1.txt');

fid = fopen('1.txt','r') ;

C = fscanf(fid,'%c');

[madhan ravi]

upload your 1.txt file

Answer 1

[Image Analyst]

Try actually passing the filename to fopen():

clc
clear;
close all;
filename = fullfile(matlabroot,'1.txt');
if exist(filename, 'file')
    fid = fopen(filename ,'rt') ;
    C = fscanf(fid,'%c');
else
    message = sprintf('File does not exist', filename);
    uiwait(errordlg(message));
    return;
end

Answer 2

[Stephen23]

You need to actually pass the filename to fopen:

fnm = fullfile(matlabroot,'1.txt');
[fid,msg] = fopen(fnm,'r');
assert(fid>=3,msg)
C = fscanf(fid,'%c');
fclose(fid);

[elnaz Alikarami]

I have the same problem and non of these helped. the fid keeps being -1 and I don't know how to fix it. can someone help me please?

[Rik]

@elnaz Alikarami: you will have to post your code, ideally in your own question. Feel free to post a link here to make people aware of your question. Also have a read here and here. It will greatly improve your chances of getting an answer.