how to add 5 rows in a txt file

Hello, I need to add some stuff to a txt file already containing a matrix. I need to add everything at the very beginning of the txt.

thank you costanza

Answer 1

[Tony Mohan Varghese]

To write data to the top of the file, it is better to create a new file and write the required data to it.

1. Create a new file.
2. Write the new data to the file.
3. Read the old file and keep appending the data to the new file.

inputFile = fopen('currentFile.txt','r');
outputFile = fopen('newFile.txt','w+');

% create sample data to write to the new file 
data = [ [1:10] ; [21:30] ];

fprintf(outputFile, '%5.3f %5.3f \n',data);

while true    
   line = fgetl(inputFile);
   if ~ischar(line)
      break;
   end
   fprintf(outputFile,'%s \n',line);
end

fclose(inputFile);
fclose(outputFile);