How to read the text files sequentially?

I have 15 text files such as CASE1,CASE2.... CASE15. I would like to read all these files sequentially and use for some calculations inside nested loops. I tried this code

for k=1:15
  textFilename=['CASE' num2str(k) '.txt'];
  id=fopen('C:\Documents and Settings\guestaskin\Desktop\model\textFilename','rt');
  textdata=textscan(id,'%s%s');
  fclose(id);
end

However, it gives an error like that .. ''Invalid file identifier. Use fopen to generate a valid file identifier.''

Could you tell me what is wrong in this code and how can I make it work ?

[Image Analyst]

The FAQ will show you: http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

[Stephen23]

See Image Analyst's answer for a good explanation and solution. Storing the filenames is not required.

Answer 1

[Richard]

The main problem you have here is that you have not stored each of the text file names.

The code shown below should solve this:

textFilename = cell(1,15);
id = cell(1,15);
for k=1:15;
    textFilename{k} = fullfile('C:\Documents and Settings\guestaskin\Desktop\model',['CASE' num2str(k) '.txt']);
    id{k} = fopen(textFilename{k},'rt'); 
    textdata{k} = textscan(id{k},'%s%s'); 
    fclose(id{k}); 
end

So, here you create two empty cell arrays, the first stores the different file names, and the seconds stored the id. The remainder of the code should work as long as the files are stored in the files you specified. The error just states that you have not defined a correct file name. By creating the filename by parts (using fullfile) you are able to generate a different filename for each of the text files. Hope this helps.

[Muharrem Askin]

thank you for your help. It works :)

[Image Analyst]

He doesn't need to store each of the filenames. They can be temporary and reused during each iteration. Moreover, he doesn't need to store the file ID's. Why complicate things with storing those in a cell array when they don't need to be???

Answer 2

[Image Analyst]

The main problem is that you didn't construct the filename properly. You hard coded textFilename into the string instead of the contents of the textFilename variable into the string. Here's a better, more robust way of doing it (untested since I don't have your files)

folder = 'C:\Documents and Settings\guestaskin\Desktop\model';
for k=1:15
  baseFilename = sprintf('CASE%d.txt', k);
  fullFileName = fullfile(folder, baseFileName);
  if exist(fullFileName, 'file')
    id=fopen(\textFilename','rt');
    textdata{k} = textscan(id,'%s%s');
    fclose(id);
  else
    warningMessage = sprintf('Warning: file does not exist:\n%s', fullFileName);
    uiwait(warndlg(warningMessage);
    textdata{k} = warningMessage;
  end
end