[RESOLVED] WINAPI FindFirstFile & FindNextFile problem

[k_nenad]

Hi all,

I'm trying to get the list of files in a directory using WINAPI functions FindFirstFile and FindNextFile.
The problem is that WIN32_FIND_DATA.cFileName returns only the first character of the file name.
This is a console application created in Microsoft Visual C# 2008 Express Edition.
Here is the code. Do you have any ideas what is wrong?

Thanks

using System;
using System.IO;
using System.Runtime.InteropServices;

namespace DirectoryWINAPI
{
    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;
    }

    class Program
    {
        [DllImport("kernel32", CharSet = CharSet.Auto)]
        public static extern IntPtr FindFirstFile(string lpFileName, out WIN32_FIND_DATA lpFindFileData);

        [DllImport("kernel32", CharSet = CharSet.Auto)]
        public static extern bool FindNextFile(IntPtr hFindFile, out WIN32_FIND_DATA lpFindFileData);

        [DllImport("kernel32", CharSet = CharSet.Auto)]
        public static extern bool FindClose(IntPtr hFindFile);

        static void Main(string[] args)
        {
            StreamWriter sw = new StreamWriter("dir.txt", false);
            string dir = Path.GetFullPath(System.IO.Directory.GetCurrentDirectory());
            WIN32_FIND_DATA wfd = new WIN32_FIND_DATA();
            IntPtr h = FindFirstFile((dir + @"\*.*"), out wfd);
            while (FindNextFile(h, out wfd))
                sw.WriteLine(wfd.cFileName);
            FindClose(h);
            sw.Flush();
            sw.Close();
        }
    }
}

[k_nenad]

The problem is solved by adding:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]

before

struct WIN32_FIND_DATA

Thanks

[Arjay]

Are you aware that the .Net environment has directory and file classes built-in?

See DirectoryInfo and FileInfo classes in Msdn.

[k_nenad]

Yes, but it's much slower, especially if I use FileInfo.Length.

[Arjay]

It might have to do with how you've written the C# code.

[k_nenad]

Here is a sample app:

using System;
using System.IO;
using System.Collections.Generic;

namespace DirectoryList
{
    class Program
    {
        static StreamWriter sw;
        static void Main(string[] args)
        {
            sw = new StreamWriter("dir.txt", false);
            string appdir = Path.GetFullPath(Directory.GetCurrentDirectory());
            ParseDirs(appdir, "");
            sw.Flush();
            sw.Close();
        }

        static void ParseDirs(string dir, string leader)
        {
            DirectoryInfo di = new DirectoryInfo(dir);
            DirectoryInfo[] edi = di.GetDirectories();
            FileInfo[] efi = di.GetFiles();
            foreach (DirectoryInfo d in edi) 
            {
                sw.WriteLine(leader + "<" + d.Name + ">");
                ParseDirs(dir + @"\" + d.Name, leader + "\t");
            }
            foreach (FileInfo f in efi)
                sw.WriteLine(leader + f.Name + "  <" + f.Length.ToString("0,0;;0") + " b>");

        }
    }
}

This code executes 10x slower than the WINAPI version.
Can this code be optimized somehow?