How can i change a filename.

i am using this code to change a name of a file

clc;
clear all;
e=1;
for s=7:8  % Loop for total number of items 
     for t=0:9 % Loop for items in the gallery TBD =9

     f1=['Sub3D_I_', int2str(e), '_', int2str(t), '.dat']  

     Newf1=['Sub3D_I_', int2str(e), '_', int2str(t), '.dat']

     cd('D:\Folder where data is stored ')
     fid = fopen(f1, 'r');
     if fid<0 
         break

     else

         movefile(f1,Newf1)
         e=e+1;

     end
     end
  end

however i am getting this error ??? Error using ==> movefile The process cannot access the file because it is being used by another process.

Error in ==> NameChange1 at 19 movefile(f1,Newf1)

can anyone please help

Answer 1

[Guillaume]

Most (all?) operating systems won't let you rename / move a file if it's in use (meaning it's been opened). Since you open the file and never close it before trying to rename it, it is always going to fail.

Why are you opening the file before trying to move it? To check that it exists? If so, you should close the file before moving it but even that is not enough to guarantee that the move will be successful. You may have read permissions but not modify permissions, the file may have disappeared in between your test and the move, etc. In fact, the only way to know if the move will succeed is to try it. You can recover from a failed move by wrapping the move in a try ... catch statement. This is the only way to to perform a move safely.

Also, you don't need (and shouldn't) cd into the directory. Much better is to specify the full path of the files in the move. So:

e=1;  %what a bad name for a variable. How about filecount instead?
folder = 'D:\somewhere\where\the\file\is';
for s=7:8  % Loop for total number of items 
   for t=0:9 % Loop for items in the gallery TBD =9
     f1 = sprintf('Sub3D_I%d_%d.dat', e, t); %more readable in my opinion
     Newf1 = sprintf('Sub3D_I_%d_%d.dat', e, t); %same
     try
        movefile(fullfile(folder, f1), fullfile(folder, Newf1));
        e = e + 1;
    catch
        break;
   end
end

[Walter Roberson]

Unix operating systems allow you to move a file that is open. However, Unix operating systems do not allow you to move a file to itself, which is being done here because the f1 and Newf1 are the same.