C# 从文件路径中获取文件类型名称

Question

I have implemented all required code to get file type name from file path and it is working successfully but it returns subtracted type name eg if file path of .pdb or .pdf file then it will return "obe Acrobat Document" instead of "Adobe Acrobat Document"

I have used shell32.dll. I am not getting what happens please, help me to get rid out of it.

Source code:

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Auto)]
    internal struct SHFILEINFO
    {            
        public IntPtr hIcon;            
        public IntPtr iIcon;            
        public uint dwAttributes;            
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
        public string szDisplayName;            
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
        public string szTypeName;
    };

internal class Win32
{            
    public const uint FILE_ATTRIBUTE_NORMAL = 0x80;            
    public const uint FILE_ATTRIBUTE_DIRECTORY = 0x10;            
    public const uint SHGFI_TYPENAME = 0x000000400;            
    public const uint SHGFI_USEFILEATTRIBUTES = 0x000000010;            
    internal const uint SHGFI_SYSICONINDEX = 0x000004000;            
    internal const int ILD_TRANSPARENT = 0x1;            
    internal const uint SHGFI_ICON = 0x100;            
    internal const uint SHGFI_LARGEICON = 0x0; 
    internal const uint SHGFI_SMALLICON = 0x1; 

    [DllImport("shell32.dll", CharSet=CharSet.Unicode)]
    internal static extern IntPtr SHGetFileInfo
        (
            string pszPath, 
            uint dwFileAttributes, 
            ref SHFILEINFO psfi, 
            uint cbSizeFileInfo, 
            uint uFlags
        );

    [DllImport("shell32.dll", CharSet = CharSet.Auto)]
    internal static extern int ExtractIconEx
        (
            string stExeFileName, 
            int nIconIndex, 
            ref IntPtr phiconLarge, 
            ref IntPtr phiconSmall, 
            int nIcons
        );

    [DllImport("comctl32.dll", SetLastError = true)]
    internal static extern IntPtr ImageList_GetIcon
        (
            IntPtr himl, 
            int i, 
            int flags
        );

    [DllImport("user32.dll")]
    internal static extern bool DestroyIcon(IntPtr hIcon);
}

internal static string GetFileType(string filename)
{
    SHFILEINFO shinfo = new SHFILEINFO();
    Win32.SHGetFileInfo
        (
                filename,
                Win32.FILE_ATTRIBUTE_NORMAL,
                ref shinfo, (uint)Marshal.SizeOf(shinfo),
                Win32.SHGFI_TYPENAME |
                Win32.SHGFI_USEFILEATTRIBUTES
            );

    return shinfo.szTypeName; //It return "obe Acrobat Document" Instead of "Adobe Acrobat Document"
}

Answer 1

The iIcon field in the C++ struct has type int.So, I just have to set the type of iIcon int only, not IntPtr. IntPtr works as per system platform so. I just set int type to iIcon like,

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Auto)]
internal struct SHFILEINFO
{            
    public IntPtr hIcon;            
    public int iIcon;            
    public uint dwAttributes;            
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
    public string szDisplayName;            
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
    public string szTypeName;
};

And It's working fine...