Write in a file, one ligne before the last one

Hi

So i have a function file, and i want to write inside the file. ( sounds weired i know)

but i want toto write one ligne before the last line in the function script.

i made up this eexemole to explaine :

function [out_1, out_2] = test (in_1, )in_2

stuf ... % thethe main code of the function 

end

i am using this code toto write inside the function file

file = fopen('test.m','a+')
fprintf(file,'%c','stuf')
fclose(file)

the idea is i want to write before the "end" of the function.

is there a way to Go back 3 caracters or up one ligne to sstart writing?

Answer 1

[Image Analyst]

Yes, open it, read all the lines, counting them in a loop. Then have a second loop reading from the input file, and writing to the output file. When the line number is the count minus 1, call your fprintf() to the output file. Then you can close both files and delete the input file and rename your output file using movefile() if you want. Easy, but let me know if you can't figure it out.

[Khalala Mamouri]

Hi, This is the working code :

this is the code i am using to transfer data from text to text1

     fid_in = fopen('Test.txt');
    
      g = textscan(fid_in,'%s','delimiter','\n');  % Count N of lines
      N_lines = length(g{1});                      %

    frewind(fid_in);                               % Re initialize fgetl
    fid_out = fopen( 'test2.txt', 'w' );
    
    lol = fgetl(fid_in);                           % Copiying data to the second file
    for i = 1:N_lines-1
            fprintf( fid_out, '%s \n', lol );
      lol = fgetl(fid_in);
    end


    new_output = 'Henry the IXth ';                   % Add a line N
    fprintf( fid_out, '%s\n', new_output );
    
    
fclose( fid_out );
fclose( fid_in )  ;                                  % close all that things
%delete('Test.txt');                                 % Delete old file 
rename = strcat(f,'Hello',txt) ;                     % << How to rename the file ?

So at the end we need to get that :

test.txt               test1.txt

Orange                 Orange
Blue                   Blue
Green                  Henry the IXth I am

I am not sure how to do to rename the file ? can you please help me ?

[Image Analyst]

Add this robust code:

originalFileName = fullfile(pwd, 'Test.txt');
newFileName = fullfile(pwd, 'Test2.txt');
if isfile(originalFileName) && isfile(newFileName)
    recycle('on') % Make sure deleted file goes into recycle bin.
    delete(originalFileName); % Delete old one.
    movefile(newFileName, originalFileName); % Rename new one.
end

Answer 2

[Mario Malic]

With this, you'll get contents of the file in File_Data which is a cell size (ii,1) with character arrays.

FID = fopen('test.txt', 'r'); 
ii = 1;
tline = fgetl(FID);
File_Data{ii} = tline;
while ischar(tline)
    ii = ii+1;
    tline = fgetl(FID);
    File_Data{ii} = tline;
end
fclose(FID);

Replacing the second to last line

File_Data{numel(File_Data)-1} = 'Henry the IXth I am';

You can delete the previous file, I am not sure if fopen would overwrite the file if it has the same name.

Write the file with

FID = fopen('test1.txt','wt'); %
for p = 1:numel(File_Data)
    if File_Data{p+1} == -1 % -1 denotes the end of file
        fprintf(FID,'%s', File_Data{p});
        break
    else
        fprintf(FID,'%s\n', File_Data{p});
    end
end
fclose(FID);

[Khalala Mamouri]

Thanks Mario, both your code and mine are working,

however, i am traying to delete the old file 'Test.txt', i am not sure how to do it

this is what i am using :

movefile('New_Name.txt','Test.txt');

i keep getting this error :

The specified file is not found.

This is weard because the file is in the directory

[Mario Malic]

Command movefile as the name says will move (rename or copy) your file.

See command delete https://www.mathworks.com/help/matlab/ref/delete.html to delete your file.

[Khalala Mamouri]

To be honest i did not understand. So i want to change the name of a file, lets say : Old_Name.txt to New_name.txt. How is it done ? thank you

[Mario Malic]

You changed the order of files

From the documentation:

movefile source destination
% 
movefile 'old.txt' 'new.txt'