Re: Next "available" File/Folder Name,...

Hector Santos <>
Wed, 27 Jan 2010 12:34:53 -0500
Kerem G?mr?kc? wrote:

Hi Stefan,

Even if there is such a thing, what value would it give to you? Once
you had that "next available file/folder name" and just before you can
create it, your program can be preempted and someone else can
calculate this file/folder and create it, so what value will your
prior call to this imaginary function have?. Having a function that
does this as an API is subject to race conditions, so it is per se
useless, unless tightly coupled with a file/foldeer creation call. The
only sure thing is a function that tries to *create* the next possible

Yes, you are right on that. But it is quite sure that there will be no
race condition/deadlock, because the access to the folder is only
restricted to
a special process that only runs single instance, system and sessionwide
in a special account and the folder (where the subfolders/files) will be
created) has special NTFS restrictions only for the process user context.

Stefan's suggestion still applies. However, where (count) do you
begin? If its a single process/thread, you might as well use a
FindFirstFile()/FindNextFile() to get the highest count using a "New
File*.txt" specification, then +1 for the new file. If the applet is
24x7, then you can get that high count at startup.

Off hand:

int GetNextCount()
    const char *pszSpec = "new file(*).txt";
    int nHigh = 0;
    WIN32_FIND_DATA fd;
    HANDLE ff = FindFirstFile(pszSpec, &fd);
    if (ff != INVALID_HANDLE_VALUE) {
       do {
          int n = atoi(fd.cFileName+9);
          if (n > nHigh) nHigh = n;
       } while(FindNextFile(ff,&fd));
    return nHigh+1;


   CString nfn;
   nfn.Format("New File(%d)",GetNextCount())

Fine tune this to your specific paths/names. But has Stefan
highlighted, if you going to be having multiple access points,
threads, processes, etc, then doing a exclusive file open with
CreateFile() will work (after getting the highest count), then use a
loop to increment again if the file was created after the
findfirst/next search.


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