How to create cell array with a function?

I need to create a function that takes each line from a text file and stocks this line in a cell array. The text file goes as so:

A B C D E
E D C B A
A D C B E

and so on. (the number of lines is unknown) I need it to stock as so:

 {'A','B','C','D','E'}
 {'E','D','C','B','A'}

and so on. My code is:

function [ T ] = ReadFile( File ) %imposed as format of the function
fid=fopen(File,'rt');
if fid~=-1
    disp('File open.')
    str=0;
    i=1;
    while ischar(str)
        str=fgetl(fid);
    T(i).items=strsplit(str) %here is how I stock the lines in a cell array, the field has to be named items. 
    i=i+1;
    end
else
    error('File not opened correctly')
end

However, I cannot seem to see the cell array in my main file, when I call the function. What am I doing wrong? Thank you

Answer 1

[Stephen23]

A more efficient concept would use something like textscan:

 function C = myfun(file)
 opt = {'CollectOutput',true};
 fmt = repmat('%s',1,5);
 [fid,msg] = fopen(file);
 assert(fid>=3,msg)
 C = textscan(fid,fmt,opt{:});
 fclose(fid);
 C = num2cell(C{1},2); % nested cell array for each row
 # C = C{1}; % one cell array with all values
 end

and then simply call it like this:

 C = myfun('myfilename')

[Dada]

The thing is, when I paste my function in a simple script - it works! The call array is created just the way I need it. But when I try to call my function, it doesn't show my cell array. Technically - I think it doesn't create it.

function [ T ] = ReadFile( File )
fid=fopen(File,'rt');
if fid~=-1
    disp('File open.')
    t=fgetl(fid);
    T(1).items=strsplit(t);
    i=2;
    while ischar(str)
        t=fgetl(fid);
        T(i).items={strsplit(t)};
        i=i+1;
    end
else
    error('File didn''t open correctly.')
end
fclose(fid);
end

If I simply paste this in a script, my cell array T is the way I need it. But when I try to create it by callin the function, I can't.. Why?

T=ReadFile(File);

This shows me the error

Output argument "T" (and maybe others) not assigned during call to "ReadFile".

[Stephen23]

Once I fixed some bugs (e.g. you use str but never define its value, but it probably exists in your workspace which is why the script works) your code works for me. Your description "I can't.. " does not give any information for me to understand the situation. Does "I can't.." mean that you are possessed by a strange and magical force that prevents your hand from pressing the enter button, or does "I can't.. " mean that the code throws an error (if so, please give the complete error message), or does "I can't.. " mean that the code runs but does not return the expected output (if so, please upload your data, and explain how you are calling this function), or perhaps "I can't.. " means that your computer bursts into flames when you tried. Should I call the fire brigade?

Note that testing fid~=-1 is not robust, as there are also other error codes and MATLAB already outputs an error message, so a big improvement would be:

 [fid,msg] = fopen(...);
 assert(fid>=3,msg)
 ... your code

No ugly and buggy ifs are required.

[Dada]

I appreciate the sarcasm Stephen, even though it was not needed. ;) I did put my WHOLE code, but maybe I didn't express myself well enough. So let me restart.(I did end up correcting the str value that was not given, I forgot to replace ths tr with the variable t), the function go as so:

function [ T ] = ReadFile( File )
fid=fopen(File,'rt');
if fid~=-1
    disp('File open.')
    t=fgetl(fid);
    T(1).items=strsplit(t);
    i=2;
    while ischar(t)
        t=fgetl(fid);
        T(i).items={strsplit(t)};
        i=i+1;
    end
else
    error('File didn''t open correctly.')
end
fclose(fid);
end

Please note that the verification fid~=-1 is mandatory, since this is a class exercice and that's how we got to do it. Then I go into my main script, where the FIRST line is me calling my function, since this is the first step of the exercice:

T=ReadFile('File.txt');

I need to get the complete cell array T in my main script, since I will need in in the next steps of the exercice. However, it right away shows me this COMPLETE error:

Output argument "T" (and maybe others) not assigned during call to "ReadFile".

Error in TP5_Q2 (line 13)
T=ReadFile('File.txt');

So what am I doing wrong? And no, no fire brigade will be needed, thank you for asking.

[Stephen23]

Your code works for me:

>> T = ReadFile('answers.txt')
File open.
T = 
1x6 struct array with fields:
    items

May be you have multiple versions of your function saved, and an older version is getting called (and not the version that you think/want). Tell us what the output of this command is:

 which ReadFile -all

Is this the location which you expect? Are multiple files listed? Is the directory where you have your function saved on the MATLAB search path?