File count from a folder

Question

How do I get number of Files from a folder using ASP.NET with C#?

Answer 1

To get the count of certain type extensions using LINQ you could use this simple code:

Dim exts() As String = {".docx", ".ppt", ".pdf"}

Dim query = (From f As FileInfo In directory.GetFiles()).Where(Function(f) exts.Contains(f.Extension.ToLower()))

Response.Write(query.Count())

Answer 2

System.IO.Directory myDir = GetMyDirectoryForTheExample();
int count = myDir.GetFiles().Length;

Answer 3

int fileCount = Directory.GetFiles(path, "*.*", SearchOption.AllDirectories).Length; // Will Retrieve count of all files in directry and sub directries

int fileCount = Directory.GetFiles(path, "*.*", SearchOption.TopDirectory).Length; // Will Retrieve count of all files in directry but not sub directries

int fileCount = Directory.GetFiles(path, "*.xml", SearchOption.AllDirectories).Length; // Will Retrieve count of files XML extension in directry and sub directries

Answer 4

.NET methods Directory.GetFiles(dir) or DirectoryInfo.GetFiles() are not very fast for just getting a total file count. If you use this file count method very heavily, consider using WinAPI directly, which saves about 50% of time.

Here's the WinAPI approach where I encapsulate WinAPI calls to a C# method:

int GetFileCount(string dir, bool includeSubdirectories = false)

Complete code:

[Serializable, StructLayout(LayoutKind.Sequential)]
private struct WIN32_FIND_DATA
{
    public int dwFileAttributes;
    public int ftCreationTime_dwLowDateTime;
    public int ftCreationTime_dwHighDateTime;
    public int ftLastAccessTime_dwLowDateTime;
    public int ftLastAccessTime_dwHighDateTime;
    public int ftLastWriteTime_dwLowDateTime;
    public int ftLastWriteTime_dwHighDateTime;
    public int nFileSizeHigh;
    public int nFileSizeLow;
    public int dwReserved0;
    public int dwReserved1;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
    public string cFileName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]
    public string cAlternateFileName;
}

[DllImport("kernel32.dll")]
private static extern IntPtr FindFirstFile(string pFileName, ref WIN32_FIND_DATA pFindFileData);
[DllImport("kernel32.dll")]
private static extern bool FindNextFile(IntPtr hFindFile, ref WIN32_FIND_DATA lpFindFileData);
[DllImport("kernel32.dll")]
private static extern bool FindClose(IntPtr hFindFile);

private static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);
private const int FILE_ATTRIBUTE_DIRECTORY = 16;

private int GetFileCount(string dir, bool includeSubdirectories = false)
{
    string searchPattern = Path.Combine(dir, "*");

    var findFileData = new WIN32_FIND_DATA();
    IntPtr hFindFile = FindFirstFile(searchPattern, ref findFileData);
    if (hFindFile == INVALID_HANDLE_VALUE)
        throw new Exception("Directory not found: " + dir);

    int fileCount = 0;
    do
    {
        if (findFileData.dwFileAttributes != FILE_ATTRIBUTE_DIRECTORY)
        {
            fileCount++;
            continue;
        }

        if (includeSubdirectories && findFileData.cFileName != "." && findFileData.cFileName != "..")
        {
            string subDir = Path.Combine(dir, findFileData.cFileName);
            fileCount += GetFileCount(subDir, true);
        }
    }
    while (FindNextFile(hFindFile, ref findFileData));

    FindClose(hFindFile);

    return fileCount;
}

When I search in a folder with 13000 files on my computer - Average: 110ms

int fileCount = GetFileCount(searchDir, true); // using WinAPI

.NET built-in method: Directory.GetFiles(dir) - Average: 230ms

int fileCount = Directory.GetFiles(searchDir, "*", SearchOption.AllDirectories).Length;

Note: first run of either of the methods will be 60% - 100% slower respectively because the hard drive takes a little longer to locate the sectors. Subsequent calls will be semi-cached by Windows, I guess.