Next "available" File/Folder Name,...
in [Framework]
|
From: Kerem Gümrükcü on 27 Jan 2010 04:00 Hi, i am looking for some API that will give me the next available file/folder name if the file/folder aleady exists. Example: you have a file named "New Text.txt", o the operating system suggests here "New Text(1).txt" if you create a new file within the shell. Is there any API that could give me the next available name for a file if i provide a filename as input? I guess its some shell interface or function, but i could not find anything so far,... Thanks in advance,... Regards Kerem -- ----------------------- Beste Gr�sse / Best regards / Votre bien devoue Kerem G�mr�kc� Latest Project: http://www.pro-it-education.de/software/deviceremover Latest Open-Source Projects: http://entwicklung.junetz.de -----------------------
From: Jeff Gaines on 27 Jan 2010 04:18 On 27/01/2010 in message <uogn98ynKHA.3636(a)TK2MSFTNGP06.phx.gbl> Kerem G�mr�kc� wrote: >Hi, > >i am looking for some API that will give me the next >available file/folder name if the file/folder aleady >exists. Example: you have a file named "New Text.txt", >o the operating system suggests here "New Text(1).txt" >if you create a new file within the shell. Is there any API >that could give me the next available name for a file if >i provide a filename as input? I guess its some shell interface >or function, but i could not find anything so far,... I use the following for files: internal static string GetUniqueFilePath(string filePathIN) { int count = 1; string result = filePathIN; FileInfo fInfo = new FileInfo(result); if (fInfo.Exists) { do { result = filePathIN + "." + count.ToString("0000"); count++; fInfo = new FileInfo(result); } while (fInfo.Exists); } return result; } It adds the number at the end so you would need to tweak it a bit to put the number in a different place. -- Jeff Gaines Dorset UK There are 3 types of people in this world. Those who can count, and those who can't.
From: Stefan Kuhr on 27 Jan 2010 10:35 Hi Kerem, On 1/27/2010 10:00 AM, Kerem G�mr�kc� wrote: > Hi, > > i am looking for some API that will give me the next > available file/folder name if the file/folder aleady > exists. Example: you have a file named "New Text.txt", > o the operating system suggests here "New Text(1).txt" > if you create a new file within the shell. Is there any API > that could give me the next available name for a file if > i provide a filename as input? I guess its some shell interface > or function, but i could not find anything so far,... > 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 file/folder. You mentioned PathMakeUniqueName, I never used that, does it only "suggest" the file name or does it create the file as well? If it doesn't create the file name, you will have to use that in a loop until a combination of the result of both PathMakeUniqueName and CreateFile succeed. BTW: MSDN online says that PathMakeUniqueName is suppported on W2K as well. -- S
From: Kerem Gümrükcü on 27 Jan 2010 11:25 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 file/folder. 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. > You mentioned PathMakeUniqueName, I never used that, does it only > "suggest" the file name or does it create the file as well? AFAIK (i didnt check it and will use it!) it only suggest the file name, like many shell and helper functions do with strings and URLs/Paths. > doesn't create the file name, you will have to use that in a loop until a > combination of the result of both PathMakeUniqueName and CreateFile > succeed. I implemented my own version that does a for-loop on the names until it gets a "available" name, then it does its job. > BTW: MSDN online says that PathMakeUniqueName is suppported on W2K as > well. I am always very cautious on functions i never used or know, so i always check first whether there is a (implemented) export of the function on the named library and this time i was right on checking it, because my up2date W2k system does NOT have such a export in the library! Yes, MSDN says that, but in fact it seems to be wrong since i do have a shell32.dll (5.00.3900.7155) on my W2k and it does NOT export that function at least it has no named export! But MSDN says: Minimum DLL Version shell32.dll version 5.0 or later Custom Implementation No Header shlobj.h Import library shell32.lib Minimum operating systems Windows 2000 Thats simply wrong! And what export name is that "PathYetAnotherMakeUniqueName", available since >=XP *g* Regards K. -- ----------------------- Beste Gr�sse / Best regards / Votre bien devoue Kerem G�mr�kc� Latest Project: http://www.pro-it-education.de/software/deviceremover Latest Open-Source Projects: http://entwicklung.junetz.de -----------------------
From: Hector Santos on 27 Jan 2010 12:34
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 >> file/folder. > > 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)); FindClose(ff); } return nHigh+1; } Usage: 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. -- HLS |