Preserve spaces when using fprintf with strcat to show variables, spaces and strings on screen to user

Hi,

I have had a try at getting a string ending with a space to be preserved on screen using fprintf and strcat together but cannot preserve the spaces.

B=strcat(PR1,'.mat');
filey=B
% Y='.*2'
%  if ~isempty(regexp(directory,Y))
%  end
% *****************************
%%THIS PRODUCES A LIST OF ONLY THE MAT FILES
  d=dir;
%   d1=cellstr(d)
    d1=struct2cell(d);
    d2=d1(1,:);
    d3=cellfun(@(x) regexp(x,'.mat'),d2,'uni',false);
    d4=find(~cellfun('isempty', d3));
    theMATfiles=d2(d4)'
    natsort(theMATfiles)%download natsort function from file exchange
% pwd
k=1;
% for k = 1:20
  % Create a mat filename, and load it into a structure called matData.
    matFileName = sprintf('mat%d.mat',k);
%     save(matFileName)
%     load('matData.mat')

      if exist(B, 'file')
      A = load(filey);
            fprintf(strcat('HURRAH!! File',{''},B,' does exist.\n'));
    else
  %     fprintf('File %s does not exist.\n', matFileName);
          fprintf(strcat('NOPE!! File','_',B,' does not exist.\n'));
    end

I have tried placing a space e.g. {''} but it did not work, I get the following error:

Error using fprintf
Invalid file identifier.  Use fopen to generate a valid file identifier.

Error in mat_ides_03 (line 53)
          fprintf(strcat('HURRAH!! File',{''},B,' does exist.\n'));

[Stephen23]

A good design rule when writing code is do not write any code that has already been written. For example the dir function already does most of what your code is doing:

S = dir('*.mat'); % returns only MAT files.

As an aside, a more suitable option for sorting filenames is natsortfiles:

https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort

As Jan Simon has already pointed out, you need to allocate the output of natsort (or natsortfiles) to an appropriate variable, otherwise its sorted cell array output is simply discarded and not used.

[Stephen Devlin]

Yes I found natsort yesterday, most helpful, but it won't help me with the inserting spaces into the line I need to print.

[Stephen23]

"but it won't help me with the inserting spaces.."

I did not say that it would. I did say that natsortfiles is good for sorting filenames.

[Stephen Devlin]

Sorry if any offence was caused, it wasn't intended. I had 'natsort' in the original code already, but will take a look at natsortfiles.

Answer 1

[Jan]

C = strcat('HURRAH!! File',{''},B,' does exist.\n')

This creates a cell string. Then fprintf must fail, because it accepts strings only. Use this:

fprintf('HURRAH!! File %s does exist.\n', B);

This is safer, because the file name can contain control characters like '\n'.

Note:

natsort(theMATfiles)

is useless, because the output is not caught. Do you mean:

theMATfiles = natsort(theMATfiles);

Simplification:

    d = dir;
    d1=struct2cell(d);
    d2=d1(1,:);
    d3=cellfun(@(x) regexp(x,'.mat'),d2,'uni',false);
    d4=find(~cellfun('isempty', d3));

Easier:

FileDir  = dir('*.mat');
FileName = {FileDir.name};

[Stephen23]

And to provide the correct filename order:

S = dir('*.mat');
S = natsortfiles(S);

[Stephen Devlin]

Thanks Jan and Stephen, very much appreciated, I had missed that fprintf will only accept a string.