Change names of multiple pictures inside a file

Hi everyone, I have 25+ pics in a file named 1,2,3...up to lets say 25 and want to change their names to lets say cat1, cat2,...up to cat25

the next code does indeed change the names but not in the corect order because it reads the images in this way 1,10,11 bla bla 2,20 ... so the images get all messed up,how can i change the names in the corect way ?

a ='C:\Users\nas\Desktop\0.3';
A =dir( fullfile(a, '*.jpg') );
fileNames = { A.name };
for iFile = 1 : numel( A )
  newName = fullfile(a, sprintf( '%05d.jpg', iFile ) );
  movefile( fullfile(a, fileNames{ iFile }), newName );    
end

Answer 1

[Walter Roberson]

a ='C:\Users\nas\Desktop\0.3';
A = dir( fullfile(a, '*.jpg') );
fileNames = fullfile({A.folder}, {A.name});

for iFile = 1 : numel(fileNames)
  oldname = fileNames{iFile};
  [fold, basename, ext] = fileparts(oldname);
  newbase = regexprep(basename, '.*?(\d+)$', 'cat$1')
  newName = fullfile(fold, [newbase ext]);
  movefile( oldname, newName );    
end

[lena kappa]

Thank you walter!!! have a nice day!!!