How to quickly check if folder is empty NET

Question

I have to check  if directory on disk is empty  It means  that it does not contain any folders files  I know  that there is a simple method  We get array of FileSystemInfo s and check if count of elements equals to zero  Something like that   public static bool CheckFolderEmpty string path        if  string IsNullOrEmpty path                 throw new ArgumentNullException  path               var folder   new DirectoryInfo path       if  folder Exists                return folder GetFileSystemInfos   Length    0             throw new DirectoryNotFoundException        This approach seems OK  BUT   It is very  very bad from a perspective of performance  GetFileSystemInfos   is a very hard method  Actually  it enumerates all filesystem objects of folder  gets all their properties  creates objects  fills typed array etc  And all this just to simply check Length  That s stupid  isn t it   I just profiled such code and determined  that  250 calls of such method are executed in  500ms  This is very slow and I believe  that it is possible to do it much quicker   Any suggestions

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Based in Brad Parks code       public static bool DirectoryIsEmpty string path                if  System IO Directory GetFiles path  Length  gt  0  return false           foreach  string dir in System IO Directory GetDirectories path               if   DirectoryIsEmpty dir   return false           return true

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private static void test         System Diagnostics Stopwatch sw   new System Diagnostics Stopwatch        sw Start         string    dirs   System IO Directory GetDirectories  C   Test          string   files   System IO Directory GetFiles  C   Test           if  dirs Length    0  amp  amp  files Length    0          Console WriteLine  Empty        else         Console WriteLine  Not Empty         sw Stop        Console WriteLine sw ElapsedMilliseconds       This quick test came back in 2 milliseconds for the folder when empty and when containing subfolders  amp  files  5 folders with 5 files in each

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I m sure the other answers are faster  and your question asked for whether or not a folder contained files or folders    but I d think most of the time people would consider a directory empty if it contains no files  ie It s still  empty  to me if it contains empty subdirectories    this may not fit for your usage  but may for others     public bool DirectoryIsEmpty string path          int fileCount   Directory GetFiles path  Length      if  fileCount  gt  0                return false             string   dirs   Directory GetDirectories path       foreach  string dir in dirs              if    DirectoryIsEmpty dir                   return false                     return true

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Here is something that might help you doing it  I managed to do it in two iterations     private static IEnumerable lt string gt  GetAllNonEmptyDirectories string path            var directories           Directory EnumerateDirectories path         SearchOption AllDirectories           ToList          var directoryList          from directory in directories      let isEmpty   Directory GetFiles directory         SearchOption AllDirectories  Length    0      where  isEmpty select directory        ToList          return directoryList ToList

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Since you are going to work with a DirectoryInfo object anyway  I d go with an extension  public static bool IsEmpty this DirectoryInfo directoryInfo        return directoryInfo GetFileSystemInfos   Count      0

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You could try Directory Exists path  and Directory GetFiles path  - probably less overhead  no objects - just strings etc

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Here is the extra fast solution  that I finally implemented  Here I am using WinAPI and functions FindFirstFile  FindNextFile  It allows to avoid enumeration of all items in Folder and stops right after detecting the first object in the Folder  This approach is  6     times faster  than described above  250 calls in 36ms   private static readonly IntPtr INVALID HANDLE VALUE   new IntPtr -1     StructLayout LayoutKind Sequential  CharSet   CharSet Auto   private struct WIN32 FIND DATA       public uint dwFileAttributes      public System Runtime InteropServices ComTypes FILETIME ftCreationTime      public System Runtime InteropServices ComTypes FILETIME ftLastAccessTime      public System Runtime InteropServices ComTypes FILETIME ftLastWriteTime      public uint nFileSizeHigh      public uint nFileSizeLow      public uint dwReserved0      public uint dwReserved1       MarshalAs UnmanagedType ByValTStr  SizeConst   260       public string cFileName       MarshalAs UnmanagedType ByValTStr  SizeConst   14       public string cAlternateFileName      DllImport  kernel32 dll   CharSet CharSet Auto   private static extern IntPtr FindFirstFile string lpFileName  out WIN32 FIND DATA lpFindFileData     DllImport  kernel32 dll   CharSet CharSet Auto   private static extern bool FindNextFile IntPtr hFindFile  out WIN32 FIND DATA lpFindFileData     DllImport  kernel32 dll    private static extern bool FindClose IntPtr hFindFile    public static bool CheckDirectoryEmpty Fast string path        if  string IsNullOrEmpty path                 throw new ArgumentNullException path              if  Directory Exists path                 if  path EndsWith Path DirectorySeparatorChar ToString                 path                 else             path    Path DirectorySeparatorChar                 WIN32 FIND DATA findData          var findHandle   FindFirstFile path  out findData            if  findHandle    INVALID HANDLE VALUE                        try                               bool empty   true                  do                                       if  findData cFileName         amp  amp  findData cFileName                                  empty   false                    while  empty  amp  amp  FindNextFile findHandle  out findData                     return empty                            finally                               FindClose findHandle                                    throw new Exception  Failed to get directory first file               Marshal GetExceptionForHR Marshal GetHRForLastWin32Error                throw new DirectoryNotFoundException        I hope it will be useful for somebody in the future

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You will have to go the hard drive for this information in any case  and this alone will trump any object creation and array filling

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I use this for folders and files  don t know if it s optimal       if Directory GetFileSystemEntries path  Length    0

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Thanks  everybody  for replies  I tried to use Directory GetFiles   and Directory GetDirectories   methods  Good news  The performance improved  twice  229 calls in 221ms  But also I hope  that it is possible to avoid enumeration of all items in the folder  Agree  that still the unnecessary job is executing  Don t you think so   After all investigations  I reached a conclusion  that under pure  NET further optimiation is impossible  I am going to play with WinAPI s FindFirstFile function  Hope it will help

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There is a new feature in Directory and DirectoryInfo in  NET 4 that allows them to return an IEnumerable instead of an array  and start returning results before reading all the directory contents    What s New in the BCL in  NET 4 Beta 1 Directory EnumerateFileSystemEntries method overloads   public bool IsDirectoryEmpty string path        IEnumerable lt string gt  items   Directory EnumerateFileSystemEntries path       using  IEnumerator lt string gt  en   items GetEnumerator                  return  en MoveNext                EDIT  seeing that answer again  I realize this code can be made much simpler     public bool IsDirectoryEmpty string path        return  Directory EnumerateFileSystemEntries path  Any

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Some time you might want to verify whether any files exist inside sub directories and ignore those empty sub directories  in this case you can used method below   public bool isDirectoryContainFiles string path        if   Directory Exists path   return false      return Directory EnumerateFiles path       SearchOption AllDirectories  Any

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I m not aware of a method that will succinctly tell you if a given folder contains any other folders or files  however  using   Directory GetFiles path    amp  Directory GetDirectories path     should help performance since both of these methods will only return an array of strings with the names of the files directories rather than entire FileSystemInfo objects

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My code is amazing it just took 00 00 00 0007143  less than milisecond with 34 file in folder     System Diagnostics Stopwatch sw   new System Diagnostics Stopwatch        sw Start          bool IsEmptyDirectory    Directory GetFiles  d   pdf   Length    0         sw Stop         Console WriteLine sw Elapsed

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Use this  It s simple   Public Function IsDirectoryEmpty ByVal strDirectoryPath As String  As Boolean         Dim s   As String                 Directory GetFiles strDirectoryPath          If s Length   0 Then             Return True         Else             Return False         End If     End Function

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I don t know about the performance statistics on this one  but have you tried using the Directory GetFiles   static method    It returns a string array containing filenames  not FileInfos  and you can check the length of the array in the same way as above

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Easy and simple  public static bool DirIsEmpty string path        int num   Directory GetFiles path  Length   Directory GetDirectories path  Length      return num    0

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If you don t mind leaving pure C  and going for WinApi calls  then you might want to consider the PathIsDirectoryEmpty   function  According to the MSDN  the function      Returns TRUE if pszPath is an empty directory  Returns FALSE if pszPath is not a directory  or if it contains at least one file other than     or         That seems to be a function which does exactly what you want  so it is probably well optimised for that task  although I haven t tested that    To call it from C   the pinvoke net site should help you   Unfortunately  it doesn t describe this certain function yet  but you should be able to find some functions with similar arguments and return type there and use them as the basis for your call  If you look again into the MSDN  it says that the DLL to import from is shlwapi dll

[.net] How to quickly check if folder is empty (.NET)?

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